Published Customer Technical Papers
Title | Authors | Publication | Abstract | Key Words |
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“Prompt Emission of Relativistic Protons up to GeV Energies from M6.4-class Solar Flare on July 17, 2023” | MN de Oliveira, CE Navia, AA Nepomuceno | Brazilian Journal of Physics, 2024 | We show evidence of particle acceleration at GEV energies associated directly with protons from the prompt emission of a long-duration M6-class solar flare on July 17, 2023, rather than from protons acceleration by shocks from its associated Coronal Mass Ejection (CME), which erupted with a speed of 1342 km/s. Solar Energetic Particles (SEP) accelerated by the blast have reached Earth, up to an almost S3 (strong) category of a radiation storm on the NOAA scale. Also, we show a temporal correlation between the fast rising of GOES-16 proton and muon excess at ground level in the count rate of the New-Tupi muon detector at the central SAA region. A Monte Carlo spectral analysis based on muon excess at New-Tupi is consistent with the acceleration of electrons and protons (ions) up to relativistic energies (GeV energy range) in the impulsive phase of the flare. In addition, we present another two marginal particle excesses (with low confidence) at ground-level detectors in correlation with the solar flare prompt emission. | Sun activity, High-speed stream, Cosmic rays modulation |
“Label-free Multimodal Polarization-sensitive Optical Microscope for Multiparametric Quantitative Characterization of Collagen” | Lingxiao Yang, Rishyashring R. Iyer, Janet E. Sorrells, Eric J. Chaney, Stephen A. Boppart | Optica, Vol. 11, https://opg.optica.org/optica/issue.cfm?volume=11&issue=2, pp. 155-165, (2024), https://doi.org/10.1364/OPTICA.505377 | Collagen is an essential component of biological tissues with a variety of subtypes. To be able to capture these subtypes, fully exploit the polarization-sensitive light-collagen interactions, and provide comprehensive information of collagen, we integrated polarization-sensitive second-harmonic generation (PSHG) microscopy, polarization-sensitive optical coherence microscopy (PSOCM), and two-photon fluorescence lifetime imaging microscopy into a single-source multimodal system in a simultaneous and spatially co-registered configuration. PSOCM information is used in the PSHG numerical model to enable accurate PSHG analysis of unsectioned fresh tissue. This polarization-sensitive multimodal system provides quantitative multiparametric characterization of collagen and facilitates the fundamental understanding of collagen in the unperturbed tissue microenvironment, which can enable future studies into the role of collagen in various diseases. | Polarization-sensitive second-harmonic generation (PSHG) microscopy, Two-photon fluorescence lifetime imaging, Polarization-sensitive optical coherence microscopy (PSOCM), microscopy |
“A Novel Fiber-Optic Beam Monitor” | S. Usherovich, P. Casolaro, A. Gottstein, I. Mateu, M. Dehnel, S. Braccini, C. Hoehr | 14th International Particle Accelerator Conference, Venice, Italy, doi: 10.18429/JACoW-IPAC2023-WEPM134 | A novel beam monitor based on Ce-doped silica optical fibers is being presented. Four fibers are mounted on the outside of a beam transport pipe, at the location of a beam stop at a proton cyclotron. The secondary radiation caused by the proton beam interaction with the beam stop is measured by the optical fibers via Radiation-Induced Emission (RIE). The light signal in the individual fibers is correlated to the proton flux closest to the fiber and can therefore be used as a detector to monitor the position of the proton beam in the beam stop. Initial testing shows that monitoring of a 150 nA beam of 18 MeV protons into a beam dump is possible. The monitor can measure relative beam current and beam displacement in X and Y as a function of magnetic steering. | Beam monitoring, Proton flux, Radiation-induced emission, Proton cyclotron, Magnetic steering |
“Rapid Bioaerosol Detection by Measuring Circular Intensity Differential Scattering (CIDS) from Single Flowing through Particle” | Yong-Le Pan, Aimable Kalume, Leonid Beresnev, Chuji Wang, Sean Kinahan, Danielle N. Rivera, Kevin K. Crown, Joshua Santarpia | Aerosol Science and Technology, 07 Nov 2023, https://doi.org/10.1080/02786826.2023.2279525 | We present an advanced optical method to measure the phase function of circular intensity differential scattering (CIDS), i.e., the normalized Mueller matrix element -S14/S11, from individual single flowing through aerosol particles. Here, a 32-anode photomultiplier tube and its associated electronics, combined with an elliptical reflector, were used to record the scattering phase functions, when a particle were illuminated by a left-handed and a right-handed circular polarization laser beam around the focus of the reflector successively. The new design does not need lock-in amplifier, polarization modulator, and rotating goniometer as the traditional setup. It can reach a particle detection ability with a maximum rate of 50,000 particle/sec. CIDS phase functions from tryptophan particles, polystyrene latex microspheres, aggregates of Escherichia coli, Bacillus subtilis spores, Yersinia rohdei, and bacteriophage MS2 were measured, the results showed that this method has the ability to rapidly discriminate between single bioaerosol and non-bioaerosol particles. | Circular intensity differential scattering (CIDS), Mueller matrix element -S14/S11, Bioaerosol particles, Chirality, Spiral, Elastic light scattering, Scattering phase function |
“ER-R: Improving Regression by Deep Learning and Prior Knowledge Utilization for Fluorescence Analysis” | Sergey Sinitsa, Nir Sochen, Mikhail Borisover, Nadia Buchanovsky, David Mendlovic, Iftach Klapp | Chemometrics and Intelligent Laboratory Systems, 26 February 2023, 104785, https://doi.org/10.1016/j.chemolab.2023.104785 | Linear regression is a dominant estimation technique in chemometrics, where there is a need for inexpensive and reliable sensors for water monitoring. However, most problems are nonlinear, such as the estimation of concentration in solution from an emitted fluorescence spectrum (EFS). Even if an estimation method gives desirable results, at some point it will be used under field conditions, where poor signal quality and less control over environmental effects are expected, leading to poor performance. In this study, we overcome these problems by implementing deep neural network (DNN) models and transfer learning technique for EFS analysis. The proposed models, R (Regression module) and ER (Encoder-Regression), outperformed linear methods and a naive DNN approach for high-quality laboratory-sampled data with a maximum mean relative error of ~11%, vs. a minimum mean relative error of 184% for the linear methods. In the case of low-quality data, which were simulated based on a real-use case, the lowest error of the linear methods climbed to 263%, whereas the proposed ER model error remained at 9%. At low concentrations, ER gave the best results for all datasets: ~3.46 ppb in the high-quality datasets, and 2.4 ppb in the low-quality datasets. | Deep learning, Organic contamination, Regression, Transfer learning, Water quality, Chemometrics |
“Development of a New High-Resolution Neutron Detector and Beta-delayed Neutron Spectroscopy of 24O” | Shree K. Neupane | PhD dissertation, University of Tennessee, 2022 | An efficient neutron detection system with good energy resolution is needed to correctly characterize the decays of neutron-rich nuclei where beta-delayed neutron emission is a dominant decay mode. Precision neutron spectroscopy probes nuclear structure effects in neutron-rich nuclei and is essential to exploit the opportunities in new-generation radioactive beam facilities. A new high-resolution neutron detector, Neutron dEtector with Xn Tracking (NEXT), has been constructed, characterized, and tested in decay and reaction experiments. Its essential capability is the neutron interaction position localization, which enables improvement in energy resolution without compromising detection efficiency in the time-of-flight measurements. Neutron-gamma discrimination capability of NEXT allows for performing experiments even in high background conditions. First measurements were performed with beta-delayed neutron emitters using NEXT at Argonne National Laboratory (ANL), focusing on fission fragments. At National Superconducting Cyclotron Laboratory (NSCL), NEXT was used alongside the Versatile Array of Neutron Detectors at Low Energy (VANDLE) to study light drip-line nuclei at and below the island of inversion with first-ever neutron spectroscopy performed for several isotopes. The neutron energy spectrum measurement of the beta-delayed neutron precursor 24O was performed for the first time at NSCL using two different neutron detector arrays: VANDLE and NEXT, accompanied by gamma spectroscopy. The beta-gamma and beta-delayed neutron measurements following the decay of 24O provided the beta decay strength distribution extending to neutron unbound states in 24F, serving as an excellent case to test the nuclear model calculations near the neutron drip line. The experimental results are compared with the shell model calculations using the standard USDA and USDB interactions and IMSRG. | Neutron spectroscopy, Neutron-gamma discrimination, NEXT, VANDLE |
“Study of One-nucleon Transfer Reactions” | Jerome Mathew Kovoor | PhD dissertation, University of Tennessee, 2022 | The structure of nuclei away from the line of stability and near the driplines in the nuclear chart has been of huge interest since the arrival of radioactive ion beam facilities. The properties of nuclei evolve as a function of proton and neutron numbers and understanding the mechanisms behind this is one of the keys to explaining the strong nuclear force. Single nucleon transfer reactions using deuteron targets are powerful probes of nuclear structure when the emitted proton or neutron is measured with high fidelity. A variety of structure phenomena are observed in the beryllium isotopes marking them particularly attractive for nuclear structure studies. The structure of 13Be offers insights into the N=8 shell gap, the nature of the Borromean nucleus 14Be, the influence of continuum, and the nature of neutron drip-line nuclei. However, despite the significant number of experiments performed over the last three decades, the energies and ordering of the low-lying resonances are less certain. A 12Be(d,p)13Be transfer reaction was performed in inverse kinematics at ISAC II at TRIUMF. The 12Be beam at 9.5 MeV/u interacted with the novel IRIS solid D2 target, and ejectiles and recoils were detected in an annular silicon detector array and two delta E -E telescopes, respectively. A Q-value plot showing the population of resonances in the 13Be continuum was obtained, and it was fitted using GEANT4 simulations, in combination with Bayesian optimization. An angular distribution of the lowest-lying strength in 13Be was obtained, and it was fitted with DWBA calculations using different combinations of optical model potentials. Results from this work will be presented here, along with interpretations of five previous works performed on 13Be, in comparison with our data. The NEXT detector is a novel, high precision, segmented neutron detector which offers excellent position and timing resolution. It uses a pulse shape discriminating plastic v scintillator, which is crucial in identifying neutrons from a gamma-ray background in reaction experiments. A 20Ne(d,n)21Na proton transfer reaction was performed at ReA6 at NSCL to benchmark this detector for reaction experiment studies. The details and preliminary results of this experiment will also be presented. | Borromean Nucleus, ISAC II TRIUMF, Segmented Neutron Detector |
“Beta-delayed Neutron Emission Spectroscopy in the 78Ni Region and Development of YSO-based Implantation Detector” | Maninder Singh | PhD dissertation, University of Tennessee, 2022 | Decays of Cu isotopes provide a laboratory to study the properties for nearly doubly-magic nuclei with a significant neutron excess which are also relevant for the r-process models. The beta-decay properties of doubly-magic 78Ni (N=50) are imprinted in the neighboring Cu decay, nuclei with a single proton outside the Z=28 core. The investigated isotopes 79,80,81Cu are strong beta-delayed neutron precursors, suggesting that their decay strength distribution lies above neutron separation energies in 79,80,81Zn daughters. For decay studies, a segmented scintillator YSO (Y2SiO5:Ce doped) based implantation detector was developed at the University of Tennessee, Knoxville. The detector is compact in structure and offers good spatial and timing resolution, crucial for ion-β correlations and time-of-flight (ToF) based β-delayed neutron emission spectroscopy, respectively. The detector was employed as a part of the BRIKEN neutron counter at the Radioactive Isotope Beam Factory (RIBF) at RIKEN Nishina Center in Japan, aiming to measure one- and two neutron emission probabilities (Pn,2n) for nuclei around the 78Ni region. Another variant of the detector with a more advanced design was used along with VANDLE (Versatile Array for Neutron Detection at Low Energy) to conduct spectroscopy of β-delayed neutrons in the same region. Reconstruction of the feeding intensities requires analysis of neutron-gamma cascades, as is suggested by the statistical model. This work reports the first direct measurements of β-decay strength to neutron-unbound states in the decay of 81,80,79Cu. The results from the experiment are compared to shell-model calculations with various sets of single-particle energies and residual interactions. Finally, predictions for 78Ni decay are made based on the model best-describing 79Cu. | YSO Scintillator, BRIKEN Neutron Counter, RIKEN Nishina Center, Ni Decay |
“64-Channel Label-Free Fluorescence Detection and Single-Particle Counting Device” | Siying Chen, Xianda Du, He Chen, Pan Guo, Yinchao Zhang, Huiyun Wu | Applied Optics Vol. 61, Issue 17, pp. 5067-5075 (2022), https://doi.org/10.1364/AO.458807 | A 64-channel detection system for laser-induced fluorescence (LIF) detection at the cell level is established and applied to single event counting. Generally, fluorescence detection at the cellular level requires a dyeing label to enhance the scattered light intensity for the photodetector. However, the dyeing labels, such as fluorophores, probes, and dyes, complicate sample preparation and increase cytotoxicity in the process. Therefore, label-free detection becomes essential for in vivo research. The presented 64-channel detection system is designed for label-free detection with the ability to record feeble emissions. Two linear photodetector devices are included in the system, extending the wavelength detection range to 366–680 nm with an improved spectral resolution at an average of 4.9 nm. The performance of the system was validated by detecting unlabeled human hepatocytes (L-02) and other cell-level biologic samples. In addition, the 64-channel detection system was also used for particle counting with a quartz microfluidic chip. The counting method is based on fluorescence spectra differs from those of other devices (i.e., flow cytometry and cell-sorting equipment), which use isolated irradiance intensities. | Fluorescence Correlation Spectroscopy, Fluorescence Spectroscopy, Irradiance, Laser Induced Fluorescence, Light Intensity, Visible Light |
“Dual-Wavelength-Excitation Aerosol Fluorescence Spectra Detection Using Combined Spectrometer with Czerny-Turner Design” | Siying Chen, Yiwen Jia, He Chen, Wenhui Yang, Yupeng Luo, Zhongshi Li, Yanbao Deng, Wangshu Tan, Pan Guo, Yinchao Zhang, Jianshu Guo, Lingfei Hu, Meng Lv | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 277, 5 September 2022, 121260 | We developed a dual-wavelength-excitation aerosol fluorescence spectra detection device prototype. In our system, the 263 nm and 355 nm lasers are used to sequentially excite the fluorescence of aerosol stream, which is located spatially and temporally by two crossed infrared lasers; a bifurcated fiber bundle is applied to receive the fluorescence spectra of 274–463 nm and 374–565 nm. Besides, with a 32-channel photomultiplier tube as detector, a self-developed combined spectrometer with Czerny-Turner design is employed to detect the two band spectra in a preset timing sequence. Experiments show that the system can detect the fluorescence spectra, after dual-wavelength-excitation, of three intrinsic fluorophore samples and three bioaerosol samples. | Laser-induced Fluorescence, Dual-Wavelength-Excitation, Aerosol Fluorescence Spectra |
“Modelling and Image Reconstruction Evaluation of a Scintillation Camera with Silicone Photomultiplier” | Md Ali Sham Firdaus, Saripan M. Iqbal, Muhammad Noor Ahmad Shukri, Rokhani Fakhrul Zaman, Hashim Suhairul, Xianling Dong | J Biomed Phys Eng 2022; 12(2) | Background: Recent research on photon detection has led to the introduction of a silicone photomultiplier (SiPM) that operates at a low voltage and is insensitive to magnetic fields. Objective: This work aims to model a scintillation camera with a SiPM sensor and to evaluate the camera reconstructed images from gamma ray projection data. Material and Methods: The type of study in this research is experimental work and analytical. The scintillation camera, modelled from an SiPM sensor array SL4-30035, coupled with a scintillation material Caesium Iodide doped with Thallium (CsI(Tl)), is used in the experimental part. The performance of the camera was evaluated from reconstructed images by a back-projection technique of a radioactive source Caesium-137 (Cs-137). Results: The experiments conducted with a 1 µCi Cs-137 radioactive source have revealed that the bias voltage (Vbias) of the SiPM needs to be set to 27.8 V at an operating temperature between 43 °C to 44 °C. The radioactive source has to be placed within a 1 cm distance from the sensor to obtain the optimum projection data. Finally, the back-projection technique for image reconstruction with linear interpolation preprocessing has revealed that the Ram-Lak filter produces a better image contrast ratio compared to others. Conclusion: This research has successfully modelled a scintillation camera with SiPM that was able to reconstruct images with an 86.4% contrast ratio from gamma ray projection data. | Gamma Cameras; Silicone Photomultiplier (SiPM); Photomultiplier Tubes (PMT); Image Reconstruction; Filter Back-Projection; Radionuclide Imaging; Scintillation Counting |
“Influence of Titanium Addition on Performance of Boron-based Thermites” | Wanjun Zhao, Haiyang Wang, Dylan J. Kline, Xizheng Wang, Tao Wu, Hui Ren, Michael R. Zachariah | Chemical Engineering Journal, 20 January 2022, 134837 | Boron (B) is an attractive fuel for its high energy density, however, the native oxide shell retards boron ignition/combustion. In this study, nano titanium (nTi) powders were added into nano boron (nB)/copper oxide (CuO) and micron boron (µB)/CuO mixtures at various molar ratios. The reactivity for both nB/CuO and µB/CuO were increased significantly by ∼3-6 times with the addition of nTi. The possible mechanism for the enhanced reactivity have been investigated via the direct addition of the native oxide of titanium (TiO2). Enhancement in reactivity is partly attributed the interaction of TiO2 with the melting boron oxide (B2O3) shell. The TiO2/B2O3 mixture in non-liquid phase creates pathway for oxygen to diffuse and thus enhances the boron oxidation rate. In addition, the higher flame temperature due to reaction of Ti and CuO promotes the volatilization of B2O3 and melting of boron, resulting in faster reaction between B and CuO. | Titanium, Boron, Thermites, Reactivity, Reaction Mechanism |
“Optical Sensor System for Early Warning of Inflow Organic Matter Breach in Large-Scale Irrigation Systems and Water Treatment Systems” | Sergey Sinitsa, Nir Sochen, David Mendelovich, Mikhail Borisover, Beni Lew, Shlomo Sela-Saldinger, Vladimir Yudachev, N. Buchanovsky, Y. Kroupitski, L. Rosenfeld, I. Klap | IEEE Sensors Journal, 01 December 2021 | A growing world population together with a decrease in water resources have resulted in a deficit in water sources for agriculture. Nations with limited water resources are already using recycled treated water as a vital water source for irrigation. In 2019, treated wastewater made up 45% of the overall agricultural water consumption in Israel. Since recycling systems work continuously and are directly connected to irrigation reservoirs, there is a constant risk of irrigation system malfunctions in the treatment process. In cases of fecal origin, this may result in pathogens entering the irrigation water, the soil, and eventually the food chain. Early warning systems for biological water contamination are important in large-scale processing, yet less studied. This work proposes such a system, with a functional prototype for irrigation-water monitoring by measuring fluorescence spectra in the range of 300 – 520 nm at excitation wavelengths of 280 nm and 340 nm, to capture both tryptophan-like fluorescence and humic-like fluorescence. The prototype was successfully tested under simulated field conditions with treated irrigation water as the base substance, and milk injections to simulate dissolved organic matter breaches. Near real-time operation enabled recording biological and chemical dynamics within the substance for the sake of monitoring drift in process control. | Water Resources, Irrigation, Temperature Measurement, Sensors, Fluorescence, Monitoring, Water Conservation |
“Energetic Characteristics of Hydrogenated Amorphous Silicon Nanoparticles” | Feiyu Xu, Giorgio Nava, Prithwish Biswas, Isabelle Dulalia, Haiyang Wang, Zaira Alibay, Mark Gale, Dylan J. Kline, Brandon Wagner, Lorenzo Mangolini, Michael R. Zachariah | Chemical Engineering Journal, 29 October 2021, 133140 | In this work, we utilize a low-temperature non-equilibrium plasma to nucleate and grow sub-10 nm Si particles with varying degrees of crystallinity by tuning the level of power coupled into plasma discharge. Temperature-programmed desorption spectroscopy shows that as-prepared amorphous Si nanoparticles (a-nSi) incorporate more hydrogen than crystalline Si nanoparticles (c-nSi). Further, hydrogen is incorporated in the material in the form of higher silicon hydrides with a lower desorption temperature. Combustion cell measurements show that when formulated with KClO4, a-nSi outperforms its crystalline counterpart with respect to pressure output. The pressurization rate of a-nSi/KClO4 composite increases by a factor of six compared with nAl to 0.66 MPa·μs−1. Evidence of hydrogen release (∼730 K) from Temperature-jump time-of-flight mass spectrometry (T-Jump TOFMS) of a-nSi/KClO4 suggests the creation of Si dangling bonds prior to ignition (∼820 K), which then react exothermically with oxygen liberated from KClO4, leading to ignition. Explosive reaction of H2/O2 mixture likely contributes to the rapid pressure rise. The enhanced energetic performance of hydrogenated a-nSi compared to its crystalline counterpart suggests that incorporation of hydrogen is a promising strategy for improving the performance of nanoenergetic materials. | Silicon, Nanoparticles, Amorphous, Nanoenegetic, Combustion |
“Neutron Detection Efficiency of the Neutron dEtector with Xn Tracking (NEXT)” | S. Neupane, J. Heideman, R. Grzywacz, J. Hooker, K.L. Jones, N. Kitamura, C.R. Thornsberry, L.H. Heilbronn, M.M. Rajabali, Y. Alberty-Jones, J. Derkin, T. Massey, D. Soltesz | arXiv:2107.11276v1 [physics.ins-det] 23 Jul 2021 | An efficient neutron detection system with good energy resolution is required to correctly characterize decays of neutron-rich nuclei where β−delayed neutron emission is a dominant decay mode. The Neutron dEtector with Xn Tracking (NEXT) has been designed to measure β-delayed neutron emitters. By segmenting the detector along the neutron flight path, NEXT reduces the associated uncertainties in neutron time-of-flight measurements, improving energy resolution while maintaining detection efficiency. Detector prototypes are comprised of optically separated segments of a neutron-gamma discriminating plastic scintillator coupled to position-sensitive photomultiplier tubes. The first performance studies of this detector showed that high intrinsic neutron detection efficiency could be achieved while retaining good energy resolution. The results from the efficiency measurements using neutrons from direct reactions are presented. | Neutron Emission, Neutron Detection, Efficiency |
“Modelling and Image Reconstruction Evaluation of a Scintillation Camera with Silicone Photomultiplier” | Sham Firdaus Md Ali, M. Iqbal Saripan , Ahmad Shukri Muhammad Noor , Fakhrul Zaman Rokhani , Suhairul Hashim, Dong Xianling | Journal of Biomedical Physics and Engineering (JBPE) 2021 | Background: Recent research on photon detection has led to the introduction of a silicone photomultiplier (SiPM) that operates at a low voltage and is insensitive to magnetic fields. Objective: This work aims to model a scintillation camera with a SiPM sensor and to evaluate the camera reconstructed images from gamma ray projection data. Material and Methods: The type of study in this research is experimental work and analytical. The scintillation camera, modelled from an SiPM sensor array SL4-30035, coupled with a scintillation material Caesium Iodide doped with Thallium (CsI(Tl)), is used in the experimental part. The performance of the camera was evaluated from reconstructed images by a back-projection technique of a radioactive source Caesium-137 (Cs-137). Results: The experiments conducted with a 1 µCi Cs-137 radioactive source have revealed that the bias voltage (Vbias) of the SiPM needs to be set to 27.8 V at an operating temperature between 43 °C to 44 °C. The radioactive source has to be placed within a 1 cm distance from the sensor to obtain the optimum projection data. Finally, the back-projection technique for image reconstruction with linear interpolation preprocessing has revealed that the Ram-Lak filter produces a better image contrast ratio compared to others. Conclusion: This research has successfully modelled a scintillation camera with SiPM that was able to reconstruct images with an 86.4% contrast ratio from gamma ray projection data. | Gamma Cameras; Silicone Photomultiplier (SiPM); Photomultiplier Tubes (PMT); Image Reconstruction; Filter Back-Projection; Radionuclide Imaging; Scintillation Counting |
“Tuning the Reactivity and Energy Release Rate of I2O5 Based Ternary Thermite Systems” | Feiyu Xu, Prithwish Biswas, Giorgio Nava, Joseph Schwan, Dylan J. Kline, Miles C. Rehwoldt, Lorenzo Mangolini, Michael R. Zachariah | Combustion and Flame, Volume 228, June 2021, Pages 210-217, https://doi.org/10.1016/j.combustflame.2020.12.047 | Iodine pentoxide (I2O5) based nanothermites are one of the most promising candidates for biocidal energetic materials due to superior reactivity and high iodine content. However, the tunability of nanothermites, which is important for biocidal performance, has not been fully exploited for I2O5 based nanothermites. In this work, I2O5 with various fuels (Al, Ti, Si) and their mixtures (i.e., a ternary system) have been investigated. The reactivity and flame temperature were evaluated by a pressure cell coupled with a spectrometer. Temperature-Jump time-of-flight mass spectrometry (T-Jump TOFMS) was used to probe the reaction mechanism and iodine release behavior, along with a high-speed camera to capture the ignition event. I2O5 showed distinct reactivity with different fuels. As a result, by varying the fuel composition of ternary systems, the combustion properties can be tuned. Rapid heating experiments revealed that the reaction initiation was shifted from gas phase dominated to condensed phase dominated mechanism after introducing Ti or Si into Al/I2O5 system. Further analysis of the ternary systems found that the energy release rate correlates with burn time instead of flame temperature. This study shows an approach to tune the reactivity and energy release rate of I2O5 based nanothermites without compromising the energy density. | Nanothermite, Biocidal, Iodine pentoxide, Energy release rate |
“Silicon Nanoparticles for the Reactivity and Energetic Density Enhancement of Energetic-Biocidal Mesoparticle Composites” | Pankaj Ghildiyal, Xiang Ke, Prithwish Biswas, Giorgio Nava, Joseph Schwan, Feiyu Xu, Dylan J. Kline, Haiyang Wang, Lorenzo Mangolini, Michael R. Zachariah | ACS Appl. Mater. Interfaces 2020, Publication Date: December 29, 2020, https://doi.org/10.1021/acsami.0c17159, Copyright © 2020 American Chemical Society | Biocidal nanothermite composites show great potential in combating biological warfare threats because of their high-energy-release rates and rapid biocidal agent release. Despite their high reactivity and combustion performance, these composites suffer from low-energy density because of the voids formed due to inefficient packing of fuel and oxidizer particles. In this study, we explore the potential of plasma-synthesized ultrafine Si nanoparticles (nSi, ∼5 nm) as an energetic filler fuel to increase the energy density of Al/Ca(IO3)2 energetic-biocidal composites by filling in the voids in the microstructure. Microscopic and elemental analyses show the partial filling of mesoparticle voids by nSi, resulting in an estimated energy density enhancement of ∼21%. In addition, constant-volume combustion cell results show that nSi addition leads to a ∼2–3-fold increase in reactivity and combustion performance, as compared to Al/Ca(IO3)2 mesoparticles. Oxidation timescale analyses suggest that nSi addition can promote initiation due to faster oxygen transport through the oxide shell of Si nanoparticles. At nSi loadings higher than ∼8%, however, slower burning characteristics of nSi and sintering effects lead to an overall degradation of combustion behavior of the composites. | Mesoparticle Composites, Energetic Density, Biocidal Energetics, Si Nanoparticles, Plasma Synthesis, Nanothermites |
“Multispectral LIF-Based Standoff Detection System for the Classification of CBE Hazards by Spectral and Temporal Features” | Lea Fellner, Marian Kraus, Florian Gebert, Arne Walter, Frank Duschek | Sensors 2020, 20(9), 2524; https://doi.org/10.3390/s20092524 | Laser-induced fluorescence (LIF) is a well-established technique for monitoring chemical processes and for the standoff detection of biological substances because of its simple technical implementation and high sensitivity. Frequently, standoff LIF spectra from large molecules and bio-agents are only slightly structured and a gain of deeper information, such as classification, let alone identification, might become challenging. Improving the LIF technology by recording spectral and additionally time-resolved fluorescence emission, a significant gain of information can be achieved. This work presents results from a LIF based detection system and an analysis of the influence of time-resolved data on the classification accuracy. A multi-wavelength sub-nanosecond laser source is used to acquire spectral and time-resolved data from a standoff distance of 3.5 m. The data set contains data from seven different bacterial species and six types of oil. Classification is performed with a decision tree algorithm separately for spectral data, time-resolved data and the combination of both. The first findings show a valuable contribution of time-resolved fluorescence data to the classification of the investigated chemical and biological agents to their species level. Temporal and spectral data have been proven as partly complementary. The classification accuracy is increased from 86% for spectral data only to more than 92%. | Laser-Induced Fluorescence (LIF), Fluorescence Lifetimes, Standoff Detection, Biological Agents, Early Warning |
“Incomplete Reactions in Nanothermite Composites” | Rohit J. Jacob, Diana L. Ortiz-Montalvo, Kyle R. Overdeep, Timothy P. Weihs, Michael R. Zachariah | Journal of Applied Physics 121, 054307 (2017); https://doi.org/10.1063/1.4974963 | Exothermic reactions between oxophilic metals and transition/post transition metal-oxides have been well documented owing to their fast reaction time scales (≈10 μs). This article examines the extent of the reaction in nano-aluminum based thermite systems through a forensic inspection of the products formed during reaction. Three nanothermite systems (Al/CuO, Al/Bi2O3, and Al/WO3) were selected owing to their diverse combustion characteristics, thereby providing sufficient generality and breadth to the analysis. Microgram quantities of the sample were coated onto a fine platinum wire, which was resistively heated at high heating rates (≈105 K/s) to ignite the sample. The subsequent products were captured/quenched very rapidly (≈500 μs) in order to preserve the chemistry/morphology during initiation and subsequent reaction and were quantitatively analyzed using electron microscopy and focused ion beam cross-sectioning followed by energy dispersive X-ray spectroscopy. Elemental examination of the cross-section of the quenched particles shows that oxygen is predominantly localized in the regions containing aluminum, implying the occurrence of the redox reaction. The Al/CuO system, which has simultaneous gaseous oxygen release and ignition (TIgnition ≈ TOxygen Release), shows a substantially lower oxygen content within the product particles as opposed to Al/Bi2O3 and Al/WO3 thermites, which are postulated to undergo a condensed phase reaction (TIgnition ≪ TOxygen Release). An effective Al:O composition for the interior section was obtained for all the mixtures, with the smaller particles generally showing a higher oxygen content than the larger ones. The observed results were further corroborated with the reaction temperature, obtained using a high-speed spectro-pyrometer, and bomb calorimetry conducted on larger samples (≈15 mg). The results suggest that thermites that produce sufficient amounts of gaseous products generate smaller product particles and achieve higher extents of completion. | Nanothermite Composites |
“Use of a Position-Sensitive Multi-Anode Photomultiplier Tube for Finding Gamma-Ray Source Direction” | Sanjoy Mukhopadhyay, Richard Maurer, Paul Guss | National Security Technologies, LLC, Contract No. DE-AC52-06NA25946 DOE/NV/25946--2150 | In an urban environment where gamma-ray background counts vary rapidly, it is important to determine the angle (with respect to the detector system) of a discrete gamma-ray–emitting source for localization purposes. We have recently developed a handheld gamma-ray detection system that provides gamma-ray energy spectral data and angular position of the target source. Careful placement and orientation of individual detectors with reference to other detectors in an array can provide improved angular resolution for determining the source position by occlusion mechanism. The objectives of this project were to design and build a prototype, light-weight, hand-held, gamma-ray spectrometer with directional sensitivity. It is important for first responders in a radiological emergency to have an easy-to-use gamma spectrometric detection system that determines the incident gamma-ray energy along with the relative angular position of a point-like radioactive source in a near-field measurement (≤3 meters from the source). The technical challenge of this project, driven by search scenarios for monitoring crowds in a national special security events was to determine the relative angle of a gamma-ray–emitting source (50 μCi strong) at a distance of 3 meters from the detector in 3 minutes. We designed and built small, portable, light-weight directional gamma energy spectrometers using a position-sensitive multi-anode photomultiplier. All of three spectrometers showed remarkable (∆Θ = ± 2°) sensitivity to relative angular position of the source in near-field laboratory measurements. | Position-sensitive photomultiplier tube (PMT), Multi-anode PMT, Angular resolution, Metal channel dynode, Position calculation, Gamma-ray imaging |
“Security X-ray Screening with Modulated-Energy Pulses” | A. Arodzero, S. Boucher, P. Burstein, S.V. Kutsaev, R.C. Lanza, V. Palermo | 978-1-7281-5092-5/19/$31.00 ©2019 IEEE | This paper provides a brief overview of new screening methods that employ Modulated-Energy X-ray Pulses (MEXP) to provide a number of near-simultaneous multi-energy measurements in transmission-, backscatter-, and Computed Tomography (CT) security systems. In transmission X-ray cargo screening, these multi-energy measurements improve material discrimination, maximize penetration, and enhance contrast resolution while simultaneously reducing inspection time and dose to the environment, thus resulting in a smaller exclusion zone. In backscatter systems, the use of this method will increase penetration and improve image quality of concealed objects located deeper below the surface. Specifically, different depths within an object can be probed simultaneously. In CT, our MEXP approach mitigates the main disadvantages of the conventional dual-energy technique: a) distortion of image of the boundaries between regions with large difference in density; b) limited range of object thickness where material decomposition is valid; c) ambiguity and artifacts caused by sampling different regions due to motion of the object between interlaced pulses with distinct energies. Results of testing of the prototype of high speed Adaptive, Multi-Energy Cargo Inspection System (AMEXIS) will be presented. Progress in the development of MEXP-based backscatter inspection system, and systems for cargo screening with Adaptive CT will also be shown. | Cargo screening; Cargo Inspection; Contraband detection; X-ray radiography; X-ray backscatter; Computed Tomography. |
“Networked Gamma Radiation Detection System for Rapid Tactical Response” | Sanjoy Mukhopadhyay, Richard Maurer, Ron Wolff, Ethan Smith, Paul Guss, Stephen Mitchell | National Security Technologies, LLC, Contract No. DE-AC52-06NA25946, DOE/NV/25946--2508 | A networked gamma radiation detection system with directional sensitivity and energy spectral data acquisition capability is being developed by the National Security Technologies, LLC, to support the close and intense tactical engagement of law enforcement who carry out counter terrorism missions. In the proposed design, three clusters of 2″ × 4″ × 16″ sodium iodide crystals (4 each) with digiBASE-E (for list mode data collection) would be placed on the passenger side of a minivan. To enhance localization and facilitate rapid identification of isotopes, advanced smart real-time localization and radioisotope identification algorithms like WAVRAD (wavelet-assisted variance reduction for anomaly detection) and NSCRAD (nuisance-rejection spectral comparison ratio anomaly detection) will be incorporated. We are testing a collection of algorithms and analysis on the problem of radiation detection with a distributed sensor network, examining such a network’s associated characteristics, and also the trade-offs between false positive alarm rates, true positive alarm rates, and time to detect multiple radiation sources in a large area. Empirical and simulation analyses of critical system parameters, such as number of sensors, sensor placement, and sensor response functions, are being examined. This networked system will provide an integrated radiation detection architecture and framework with (i) a large nationally recognized search database equivalent that would help generate a common operational picture in a major radiological crisis; (ii) a robust reach back connectivity for search data to be evaluated by home teams; and, finally, (iii) a possibility of integrating search data from multi-agency responders. | Gamma radiation detection, Radioisotope identification, CsI:Na segmented scintillator |
“Development of a Position Sensitive CsI(Tl) Crystal Array” | Guo-Zhu Shi, Ruo-Fu Chen, Kun Chen, Ai-Hua Shen, Xiu-Ling Zhang, Jin-Da Chen, Cheng-Ming Du, Zheng-Guo Hu, Guang-Wei Fan | Nuclear Engineering and Technology, Volume 52, Issue 4, April 2020, Pages 835-840 | A position-sensitive CsI(Tl) crystal array coupled with the multi-anode position sensitive photomultiplier tube (PS-PMT), Hamamatsu H8500C, has been developed at the Institute of Modern Physics. An effective, fast, and economical readout circuit based on discretized positioning circuit (DPC) bridge was designed for the 64-channel multi-anode flat panel PSPMT. The horizontal and vertical position resolutions are 0.58 mm and 0.63 mm respectively for the 1.0 × 1.0 × 5.0 mm3 CsI(Tl) array, and the horizontal and vertical position resolutions are 0.86 mm and 0.80 mm respectively for the 2.0 × 2.0 × 10.0 mm3 CsI(Tl) array. These results show that the CsI(Tl) crystal array with low cost could be applied in the fields of medical imaging and high-resolution gamma camera. | CsI(Tl), Crystal array, DPC, Discretized positioning circuit, IQSP518 system |
“Conceptual Design and First Results for a Neutron Detector with Interaction Localization Capabilities” | J. Heideman, D. Pérez-Loureiro, R. Grzywacz, C.R. Thornsberry, J. Chan, L.H. Heilbronn, S.K. Neupane, K. Schmitt, M.M. Rajabali, A.R. Engelhardt, C.W. Howell, L.D. Mostella, J.S. Owens, S.C. Shadrick, E.E. Peters, A.P.D. Ramirez, S.W. Yates, K. Vaigneur | Nuclear Instruments and Methods in Physics Research, Section A: Online 14 August 2019, 162528 | A new high-precision detector for studying neutrons from beta-delayed neutron emission and direct reaction studies is proposed. The Neutron dEtector with multi-neutron (denoted Xn) Tracking (NEXT) array is designed to maintain high intrinsic neutron detection efficiency while reducing uncertainties in neutron energy measurements. A single NEXT module is composed of thin segments of plastic scintillator, each optically separated, capable of neutron-gamma discrimination. Each segmented module is coupled to position sensitive photodetectors enabling the high-precision determination of neutron time of arrival and interaction position within the active volume. A design study has been conducted based on simulations and experimental tests leading to the construction of prototype units. First results from measurements using a 252Cf neutron source and accelerator-produced monoenergetic neutrons are presented. | Beta-delayed neutron emission, Direct reactions, Neutron detection, Time of flight, Pulse shape discrimination |
"Experimental Evaluation of Depth-Encoding Absorber Designs for Prompt-Gamma Compton Imaging in Proton Therapy" | Hui-Yu Tsai, Hsin-Yu Chen, Ming-Wei Lee, Ze Wang, Sheng-Pin Tseng, Ji-Hong Hong, Meei-Ling Jan | Radiation Measurements, online 5 July 2019, 106145 | Prompt-gamma Compton imaging (PGCI) has been presented as a promising in-vivo method for proton range verification. An accurate estimation of the Bragg-peak position can potentially be achieved by imaging high-energy prompt-gamma rays (in the range of several MeV). Therefore, scintillation detectors with thick and high Z crystals are mostly used as Compton absorbers for high-energy gamma-ray detection. However, an absorber using thick crystals degrades the angular resolution unless the absorber can provide continuous depth-of-interaction (DOI) measurement. The study investigated various detector configurations using thick crystals for developing a Compton absorber with DOI resolving capability without compromising energy performance. Two groups of lutetium yttrium oxyorthosilicate (LYSO) with dimensions of 1.8 × 1.8 × 50 mm3 and 1.8 × 1.8 × 20 mm3 LYSO arrays, and each with four different surface treatments (combining crystal surface finishing and type of reflector coverage), were constructed for the study. The DOI detector utilized the dual-ended readout of pixelated scintillator arrays for depth encoding. The results revealed that the influences of type of the reflector coverage and crystal surface roughness on the performance of the DOI detectors for the 50- and 20-mm-thick LYSO differed greatly. Moreover, the combined use of the proposed partial inter-crystal reflector coverage and the unpolished surface finishing on the 50-mm-thick crystals were shown to improve the DOI resolution without compromising the energy performance but degraded the flood map quality. These results provide useful guidance for selecting an applicable Compton DOI absorber design for developing a high-performance PGCI system. | Compton camera, Crystal surface treatment, depth of interaction, Dual-ended readout, prompt gamma, Proton therapy |
"Online Discrimination of Chemical Substances using Standoff Laser‐Induced Fluorescence Signals" | M. Kraus, F. Gebert, A. Walter, C. Pargmann, F. Duschek | Journal of Chemometrics. 2019; e3121 | Chemical contamination of objects and surfaces, caused by accident or on purpose, is a common security issue. Immediate countermeasures depend on the class of risk and consequently on the characteristics of the substances. Laser‐based standoff detection techniques can help to provide information about the thread without direct contact of humans to the hazardous materials. This article explains a data acquisition and classification procedure for laser‐induced fluorescence spectra of several chemical agents. The substances are excited from a distance of 3.5 m by laser pulses of two UV wavelengths (266 and 355 nm) with less than 0.1 mJ per laser pulse and a repetition rate of 100 Hz. Each pair of simultaneously emitted laser pulses is separated using an optical delay line. Every measurement consists of a dataset of 100 spectra per wavelength containing the signal intensities in the spectral range from 250 to 680 nm, recorded by a 32‐channel photo multiplying tube array. Based on this dataset, three classification algorithms are trained which can distinguish the samples by their single spectra with an accuracy of over 98%. These predictive models, generated with decision trees, support vector machines, and neural networks, can identify all agents (eg, benzaldehyde, isoproturon, and piperine) within the current set of substances. | Chemical Agents, Classification Algorithms, Laser‐Induced Fluorescence, Machine Learning, Standoff Detection |
"New Detector Concept with Neutron Interaction Localization Capabilities" | J. Heideman, D. P´erez-Loureiro, R. Grzywacz, J. Chen, L.H. Heilbronn, S.K. Neupane, K. Schmitt, C.R. Thornsberry, M.M. Rajabali, A.R. Engelhardt, C.W. Howell, L.D. Mostella, J.S. Owens, S.C. Shadrick, E.E. Peters, A.P.D. Ramirez, S.W. Yates, S. Munoz | arXiv:1904.01662v2 [physics.ins-det] 6 Apr 2019 | A new high precision time of flight neutron detector concept for beta-delayed neutron emission and direct reaction studies is proposed. The Neutron dEtector with Xn Tracking (NEXT) array aims to maintain high intrinsic neutron detection efficiency while reducing uncertainties in neutron energy measurements. A single NEXT module will be composed of thin segments of neutron-discriminating plastic scintillator, each optically separated, coupled to a position sensitive photo-detector. By incorporating a position sensitive photo-detector with a large optically separated scintillator, NEXT will achieve high precision determination of neutron time of arrival and interaction position within the active volume. A design study has been conducted based on simulations and experimental tests leading to construction of prototype units. First results from neutron measurements will be discussed. | β-delayed Neutron Emission, Direct Reactions, Time of Flight |
"Pre-Stressing Aluminum Nanoparticles as a Strategy to Enhance Reactivity of Nanothermite Composites" | Rohit J. Jacob, Kevin J. Hill, Yong Yang, Michelle L. Pantoya, Michael R. Zachariah | Combustion and Flame, Volume 205, July 2019, Pages 33-40 | Aluminum (Al) fuel particles are used in a variety of energetic formulations yet harvesting their full chemical potential energy and increasing their energy release rate upon ignition have been a challenge and are key motivators to advancing energy generation technologies. One approach to improving combustion performance is to alter the mechanical properties of the Al particle by inducing an elevated stress state through prestressing. This study examines the combustion performance of prestressed nanoscale aluminum (nAl) particles that were annealed to temperatures ranging from 200 to 400 °C and quenched at slow (exponential) and faster (linear) cooling rates. Powder X-ray diffraction measurements show that prestressing nAl particles at 300 °C increases the strain by an order of magnitude. Constant volume combustion cell tests on nAl combined with copper oxide nanopowder (nAl + CuO) revealed higher peak pressures and pressurization rates for prestressed nAl + CuO composites compared to their untreated counterpart. High speed emission spectroscopy was employed to deduce condensed phase temperatures from the reaction confined within the combustion cell. Burn time measurements, obtained by integrating the emission spectra, were observed to correlate inversely with generated pressure. High heating rate (∼5 × 105 K/s) in-situ TEM results augment the combustion cell results. The results imply that prestressing mechanically alters the nanoparticles which subsequently accelerate the release of aluminum core through outward diffusion. This results in the rapid loss of nanostructure which was observed at the nanoscale through in-situ electron microscopy. The released aluminum thus reacts rapidly with the oxidizer in the condensed phase resulting in a faster and more violent reaction. Improved performance of prestressed nAl coupled with the simplicity of processing provides a low cost and scalable approach to improving metal fuel particle combustion. | Nanoaluminum, Prestressing, Combustion, Reactive Sintering, XRD |
"Millisecond Synthesis of CoS Nanoparticles for Highly Efficient Overall Water Splitting" | Yanan ChenShaomao XuShuze ZhuRohit Jiji JacobGlenn PastelYanbin WangYiju LiJiaqi DaiFengjuan ChenHua XieBoyang LiuYonggang LiuLourdes G. Salamanca-RibaMichael R. ZachariahTeng LiLiangbing Hu | NanoResearch, 22 February 2019, https://doi.org/10.1007/s12274-019-2304-0 | High performance and low-cost electrocatalysts for overall water splitting, i.e., catalyzing hydrogen and oxygen evolution reactions with the same material, are of great importance for large-scale, renewable energy conversion processes. Here, we report an ultrafast (~ 7 ms) synthesis technique for transition metal chalcogenide nanoparticles assisted by high temperature treatment. As a proof of concept, we demonstrate that cobalt sulfide (~ 20 nm in diameter)@ few-layer graphene (~ 2 nm in thickness) core-shell nanoparticles embedded in RGO nanosheets exhibit remarkable bifunctional electrocatalytic activity and stability for overall water splitting, which is comparable to commercial 40 wt.% platinum/carbon (Pt/C) electrocatalysts. After 60 h of continuous operation, 10 mA·cm−2 water splitting current density can still be achieved at a low potential of ~ 1.77 V without any activity decay, which is among the most active for non-noble material based electrocatalysts. The presented study provides prospects in synthesizing highly efficient bifunctional electrocatalysts for large-scale energy conversion application via a simple yet efficient technique. | Ultrafast High Temperature Synthesis, Graphene, Water Splitting |
"Development of Position Sensitive Detector Module using Scintillator and Si Photomultiplier for Hard X-Ray Imaging and Spectroscopy" | Shiv K. Goyal, Amisha P. Naik, Neelakandan P. S. Mithun, Santosh V. Vadawale, Navin Nagrani, Shreya Madhvi, Neeraj K. Tiwari, Tinkal Ladiya, Arpit R. Patel, Hitesh K. Adalja, Tanmoy Chattopadhyay, Munuswamy Shanmugam, Amogh Auknoor, Piyush Sharma, Vishnu R. Patel | Journal of Astronomical Telescopes, Instruments, and Systems, 5(1), 016001 (2018). https://doi.org/10.1117/1.JATIS.5.1.016001 | We explore the use of scintillation detectors coupled with silicon photomultipliers (SiPMs) as position sensitive hard x-ray spectroscopic detectors for potential applications in the field of high-energy astrophysics. X-ray photons on interaction with scintillation crystals generate optical photons and the distribution of these scintillation light photons is captured with the array of SiPM pixels, providing the spectral and spatial information of the incident x-ray photons. As the position is estimated by fitting the distribution of optical photons, it should be possible to achieve spatial resolution lesser than the pixel size. Development of two detector modules with CsI (Tl) and CeBr3 scintillators coupled with different sets of array of SiPM pixels is presented here. Spectral and spatial resolutions of both detector modules are characterized with experiments using x-ray lines from laboratory radioactive sources. It is shown that a faster scintillator with an array of low-noise SiPM pixels provides better spectral and spatial resolution and it is possible to achieve subpixel spatial resolution with such a detector module. | Sensors, Scintillators, Photons, Thallium, X-Rays, Scintillation, Crystals |
"Triisobutylaluminum Additive for Liquid Hydrocarbon Burn Enhancement" | Philip M. Guerieri, Rohit J. Jacob, Dylan J. Kline, Andrew Kerr, Dennis Mayo, Edward E. Foos, Michael R. Zachariah | Combustion and Flame, Volume 200, February 2019, Pages 53-59 | Metallizing hydrocarbons has received renewed attention as a potential means to increase energy density and burn rate. Particle agglomeration however, is a significant concern, impeding both performance as well as practical implementation due to system fouling. Achieving a metallized hydrocarbon without nanoparticles in suspension would avoid particle agglomeration problems. Previous proof-of-concept work with highly reactive organometallic Al-based clusters stabilized by ligands and dissolved in a hydrocarbon showed such a scheme is not only possible, but the decreased size of the cluster molecules relative to nanoparticles substantially increases reactivity and at least an order of magnitude less active aluminum. To increase understanding of how such burning rate effects manifest with dissolved aluminum, a higher valency alkyl aluminum historically used as a hypergol, triisobutylaluminum (IBu3Al), is dissolved in toluene and isolated droplet combustion is characterized showing up to 60% burning rate increase with 810 mM IBu3Al relative to that of pure toluene attributed specifically to the aluminum content of the additive molecule. Flame emission spectroscopy observing AlO emission supports the vital role of gas eruption and droplet disruption to transport additives into the flame. | Droplet combustion, Hydrocarbons, Aluminum, Organoaluminum |
"Fast Ion D-alpha Measurements Using a Bandpass-Filtered System on EAST" | J. Zhang, J. Huang, J. F. Chang, C. R. Wu, W. W. Heidbrink, M. Salewski, B. Madsen, Y. B. Zhu, M. G. von Hellermann, W. Gao, Z. Xu, and B. Wan | Review of Scientific Instruments 89, 10D121 (2018); doi: 10.1063/1.5038828 | Based on the charge exchange reaction between fast ions and a neutral beam, fast ion features can be inferred from the spectrum of Doppler-shifted Balmer-alpha light from energetic hydrogenic atoms. In order to study the interaction between instabilities and fast-ion transport, recently we extended the fast ion D-alpha (FIDA) measurements by using a combination of a bandpass filter and a photomultiplier tube (PMT) (f-FIDA). A bandpass filter selects the desired spectral band from 651 nm to 654 nm before detection by the PMT. Preliminary data from the EAST tokamak show that the active signals have been detected from reneutralized beam ions along the vertical and tangential viewing geometries. The details will be presented in this paper to primarily address the specifications and performance of f-FIDA hardware components and preliminary FIDA measurements. | Doppler-shifted Balmer-alpha light, Tokamak, Fast-ion D-alpha, FIDA, EAST |
"Ignition and Combustion Characterization of Ca(IO3)2‐based Pyrotechnic Composites with B, Al, and Ti" | Haiyang Wang, Dylan J. Kline, Miles Rehwoldt, Michael R. Zachariah | Propellants, Explosives, Pyrotechnics, 30 August 2018 https://doi.org/10.1002/prep.201800041 | This paper studies the reactive behavior of calcium iodate with Al, B and Ti fuel particles as a thermal and iodine release source for neutralization of biological materials that might be employed in weapons. Two different calcium iodate particle length scales (micron and submicron) with different fuel/oxidizer ratios were used to prepare the iodized nanopyrolants. The optimal ratio was found to be the one with equivalence ratio of 2.0 for all the three fuels. The reactivity of the pyrolants can be enhanced by dehydrating the Ca(IO3)2 or replacing the micron oxidizer particles with submicron particles. The thermal decomposition process of the pyrolants was investigated at low and high heating rate. The results show that B, Al and Ti nanoparticles can promote the decomposition of Ca(IO3)2, but the Ti nanoparticles are the most efficient, which lower temperature of the oxygen/iodine release from ∼660 °C to ∼400 °C. Thus, Ti/Ca(IO3)2 has the lowest ignition temperature of ∼400 °C. The various calcium iodate‐based pyrolants were shown to have a wide range of reactivity (1–4 orders of magnitude) and burn times (1–3 orders of magnitude), high flame temperature (1850–2800 K) and iodine loading capacity (∼20–60 wt.‐% of iodine), which makes it a promising class of biocidal energetic materials. | Nanopyrolants, Nanoparticles, Biocidal energetic materials, Pyrotechnic Composites |
"Classification of Substances Combining Standoff Laser Induced Fluorescence and Machine Learning" | Marian Kraus, Lea Fellner, Florian Gebert, Carsten Pargmann, Arne Walter and Frank Duschek | HSOA Journal of Light & Laser: Current Trends 2018, 1: 003 | Contaminated objects and areas must be handled carefully depending on the underlying pollution. There are methods which require short distances, others the collection of samples or even direct contact to the hazardous, and some of the established techniques take long to reach a conclusion. A fast standoff method for predicting the potential hazard can be achieved by examining the laser induced fluorescence spectra of the substances of interest. The samples are excited by low-energy laser pulses of two alternating wavelengths. The datasets are measured for almost 50 agents, including fuels, pesticides and bacteria and represent the basis for a subsequent classification procedure. Therefore, the investigated materials are grouped in seven classes depending on their origin and utilization. The majority of the dataset is used in a training phase to create predictive models, which are tested with the remaining signals to qualify the classification. After all, the single spectra of the test set are classified with an error rate less than 0.1 % in predicting the correct class. With a statement like this first responders would be able to choose the right preventive measure for a rescue or decontamination procedure. | Classification algorithms; Laser Induced Fluorescence (LIF); Machine learning; Standoff detection |
“High Speed 2-Dimensional Temperature Measurements of Nanothermite Composites: Probing Thermal vs. Gas Generation Effects” | Rohit J. Jacob, Dylan J. Kline, and Michael R. Zachariah | Journal of Applied Physics 123, 115902 (2018); doi: 10.1063/1.5021890, American Institute of Physics | This work investigates the reaction dynamics of metastable intermolecular composites through high speed spectrometry, pressure measurements, and high-speed color camera pyrometry. Eight mixtures including Al/CuO and Al/Fe2O3/xWO3 (x being the oxidizer mol. %) were reacted in a constant volume pressure cell as a means of tuning gas release and adiabatic temperature. A direct correlation between gas release, peak pressure, and pressurization rate was observed, but it did not correlate with temperature. When WO3 was varied as part of the stoichiometric oxidizer content, it was found that Al/Fe2O3/70% WO3 achieved the highest pressures and shortest burn time despite a fairly constant temperature between mixtures, suggesting an interplay between the endothermic Fe2O3 decomposition and the higher adiabatic flame temperature sustained by the Al/WO3 reaction in the composite. It is proposed that the lower ignition temperature of Al/WO3 leads to the initiation of the composite and its higher flame temperature enhances the gasification of Fe2O3, thus improving advection and propagation as part of a feedback loop that drives the reaction. Direct evidence of such gas release promoting reactivity was obtained through high speed pyrometry videos of the reaction. These results set the stage for nanoenergetic materials that can be tuned for specific applications through carefully chosen oxidizer mixtures. | Metastable intermolecular composites, Spectrometry, Pyrometry, Nanoenergetic materials |
“1-D Imaging Cytometry: Statistical Assays for Immunotherapy Drug Screening” | Steve S. Wang | Boston University Theses & Dissertations 2017 | Modern cancer immunotherapy involves the conditioning of endogenous T cells to fight cancerous bodies that have managed to resist or avoid detection. Recently approved antibody drugs target the immune checkpoint pathway in T cells to prevent their tolerance to cancer antigens. There exists a compelling need, especially in the drug discovery world, to develop better assays for screening and to study the underlying mechanisms of these new antibody drugs. The core motivation of my work is to develop a primary cell assay for the immune checkpoint pathway using 1-D imaging cytometry. The assay is focused on high throughput and high content screening. It takes advantage of our novel 1-D imaging cytometer platform. The assay is designed to artificially induce anergy in primary human T cells and systemically study their drug response. An automated statistical method quantifies the functional phenotypes of both healthy and anergic T cells into a single descriptive readout. Reducing localization of biomarkers into a single ‘activity score’ readout has many advantages for drug screening and characterization. Additional assays were developed to study T cell activation dynamics and other signaling events during the immune checkpoint pathway. Our 1-D instrument leverages both the high throughput aspects of traditional flow cytometry and the high spatial content of 2-D imaging cytometers. The PMC data analysis emphasizes an unbiased approach to analyze flow cytometry data, which eliminates the subjective manual gating of current cytometric methods. This is crucial to developing more accurate and reliable assays with minimal supervision and need for expert operators. The high-throughput and high-content capabilities presented enable new types of assays previously not possible with human primary T cells. Adoption of physiological relevant primary cell assays has potential to revolutionize large-scale drug screening and future applications in personalized medicine. | 1-D imaging cytometry, Flow cytometry, immunotherapy, T cell activation |
“Implementation of a Coded Aperture Imaging System for Gamma Measurement and Experimental Feasibility Tests” | Kwangdon Kim, Hakjae Lee, Jinwook Jang, Yonghyun Chung, Donghoon Lee, Chanwoo Park, Jinhun Joung,Yongkwon Kim, Kisung Lee | IEIE Transactions on Smart Processing and Computing, vol. 6, no. 1, February 2017 | Radioactive materials are used in medicine, non-destructive testing, and nuclear plants. Source localization is especially important during nuclear decommissioning and decontamination because the actual location of the radioactive source within nuclear waste is often unknown. The coded-aperture imaging technique started with space exploration and moved into X-ray and gamma ray imaging, which have imaging process characteristics similar to each other. In this study, we simulated 21x21 and 37x37 coded aperture collimators based on a modified uniformly redundant array (MURA) pattern to make a gamma imaging system that can localize a gamma-ray source. We designed a 21x21 coded aperture collimator that matches our gamma imaging detector and did feasibility experiments with the coded aperture imaging system. We evaluated the performance of each collimator, from 2 mm to 10 mm thicknesses (at 2 mm intervals) using root mean square error (RMSE) and sensitivity in a simulation. . In experimental results, the full width half maximum (FWHM) of the point source was 5.09° at the center and 4.82° at the location of the source was 9°. We will continue to improve the decoding algorithm and optimize the collimator for high-energy gamma rays emitted from a nuclear power plant. | Coded aperture, Gamma ray imaging, Image & video sensing and acquisition |
“Design & Development of Position Sensitive Detector for Hard Xray using SiPM and New Generation Scintillators” | S. K. Goyal, Amisha P. Naik, Mithun N. P. S., S. V. Vadawale, Neeraj K. Tiwari, T. Chattopadhyay, N. Nagrani, S. Madhavi, T. Ladiya, A. R. Patel, M. Shanmugam, H. L. Adalja, V. R. Patel, G. P. Ubale | Technology Development Program (TDP) of Physical Research Laboratory (PRL), Department of Space, Government of India, December 2017 | There is growing interest in high-energy astrophysics community for the development of sensitive instruments in the hard X-ray energy extending to few hundred keV. This requires position sensitive detector modules with high efficiency in the hard X-ray energy range. Here, we present development of a detector module, which consists of 25 mm x 25 mm CeBr3 scintillation detector, read out by a custom designed two dimensional array of Silicon Photo-Multipliers (SiPM). Readout of common cathode of SiPMs provides the spectral measurement whereas the readout of individual SiPM anodes provides measurement of interaction position in the crystal. Preliminary results for spectral and position measurements with the detector module are presented here. | SiPM, Silicon Photomultiplier, CeBr3, Hard X-ray imaging detector, Scintillator readout using SiPM |
“FeS2 Nanoparticles Embedded in Reduced Graphene Oxide toward Robust, High-Performance Electrocatalysts” | Y. Chen, S. Xu, Y. Li, R. J. Jacob, Y. Kuang, B. Liu, Y. Wang, G. Pastel, L. G. Salamanca-Riba, M. R. Zachariah, L. Hu | Advanced Energy Materials, 10 July 2017 DOI: 10.1002/aenm.201700482 | Developing low-cost, highly efficient, and robust earth-abundant electrocatalysts for hydrogen evolution reaction (HER) is critical for the scalable production of clean and sustainable hydrogen fuel through electrochemical water splitting. This study presents a facile approach for the synthesis of nanostructured pyrite-phase transition metal dichalcogenides as highly active, earth-abundant catalysts in electrochemical hydrogen production. Iron disulfide (FeS2) nanoparticles are in situ loaded and stabilized on reduced graphene oxide (RGO) through a current-induced high-temperature rapid thermal shock (≈12 ms) of crushed iron pyrite powder. FeS2 nanoparticles embedded in between RGO exhibit remarkably improved electrocatalytic performance for HER, achieving 10 mA cm−2 current at an overpotential as low as 139 mV versus a reversible hydrogen electrode with outstanding long-term stability under acidic conditions. The presented strategy for the design and synthesis of highly active earth-abundant nanomaterial catalysts paves the way for low-cost and large-scale electrochemical energy applications. | FeS2 Nanoparticles, Graphene, Reduced Graphene Oxide Matrix, RGO, Electrocatalysts, Dichalcogenides |
“Ultra-Broadband Two-Dimensional Electronic Spectroscopy and Pump-Probe Microscopy of Molecular Systems” | B. Spokoyny | Northwestern University, ProQuest Dissertations Publishing, 2017. 10262822 | Ultrafast spectroscopy offers an unprecedented view on the dynamic nature of chemical reactions. From charge transfer in semiconductors to folding and isomerization of proteins, these all important processes can now be monitored and in some instances even controlled on real, physical timescales. One of the biggest challenges of ultrafast science is the incredible energetic complexity of most systems. It is not uncommon to encounter macromolecules or materials with absorption spectra spanning significant portions of the visible spectrum. Monitoring a multitude of electronic and vibrational transitions, all dynamically interacting with each other on femtosecond timescales poses a truly daunting experimental task. The first part of this thesis deals with the development of a novel Two–Dimensional Electronic Spectroscopy (2DES) and its associated, advanced detection methodologies. Owing to its ultra–broadband implementation, this technique enables us to monitor femtosecond chemical dynamics that span the energetic landscape of the entire visible spectrum. In order to demonstrate the utility of our method, we apply it to two laser dye molecules, IR–144 and Cresyl Violet. Variation of photophysical properties on a microscopic scale in either man–made or naturally occurring systems can have profound implications on how we understand their macroscopic properties. Recently, inorganic hybrid perovskites have been tapped as the next generation solar energy harvesting materials. Their remarkable properties include low exciton binding energy, low exciton recombination rates and long carrier diffusion lengths. Nevertheless, considerable variability in device properties made with nearly identical preparation methods has puzzled the community. In the second part of this thesis, we use non–linear pump probe microscopy to study the heterogeneous nature of femtosecond carrier dynamics in thin film perovskites. We show that the local morphology of the perovskite thin films has a profound influence on the underlying photophysics, opening new avenues for further optimization of device performance. | Ultrafast spectroscopy, Two–Dimensional Electronic Spectroscopy (2DES), inorganic hybrid perovskites |
“Optical Gain Measurements for a Portable Plastic-Scintillator-Based Muon Tomography System” | K. Moats | Contract Report, DRDC-RDDC-2017-C102, May 2017 | A portable plastic-scintillator-based muon tomography system could be used by the Canadian Armed Forces (CAF) to image suspect Special Nuclear Material (SNM) objects that are approximately 1 m3. The main challenge for image reconstruction in a portable muon tomography system is achieving a precise angular resolution. In order to do so, the optical yield of the scintillator bars must be improved. The work in this report focuses on determining the optical gain that could be achieved in such a system by inserting optical couplers between the plastic triangular scintillating bars and the wavelength shifting fibres. This report considers four optical couplers, namely water, BC 630, EJ 500, and NOA 63, as well as de-gassed BC 630, EJ 500, and NOA 63. Test data for this system using cosmic-ray muon sources was collected at DRDC Ottawa Research Centre and was analyzed by writing code in C++ with the ROOT analysis package. It was found that the measured optical gain values are quite similar for each optical coupler. It was also found that de-gassing the optical couplers had no noticeable effect on the optical gain. Either of the optical couplers considered in this study, whether de-gassed or not, are capable of improving the optical yield of a portable plastic-scintillator-based muon tomography prototype by approximately 40%. Further study is needed to determine how much these optical couplers will improve the tracking and position resolution of a portable muon tomography system, which will allow smaller muon trackers without sacrificing angular resolution. A Geant4 optical simulation of a portable muon tomography prototype, dubbed MuPIC (Muon Portable Imager for Counter-terrorism) is underway at DRDC Ottawa Research Centre. These simulations and laboratory studies should be continued to optimize the design of this prototype for future use by the CAF to detect SNM. | Muon Tomography, Plastic Scintillator, SNM, CRIPT |
“Image-Based Phenotypic Screening with Human Primary T Cells Using One-Dimensional Imaging Cytometry with Self-Tuning Statistical-Gating Algorithms” | S.S. Wang, D.J. Ehrlich | SLAS Discovery: Advancing Life Sciences R&D, April 26, 2017 | The parallel microfluidic cytometer (PMC) is an imaging flow cytometer that operates on statistical analysis of low-pixel-count, one-dimensional (1D) line scans. It is highly efficient in data collection and operates on suspension cells. In this article, we present a supervised automated pipeline for the PMC that minimizes operator intervention by incorporating multivariate logistic regression for data scoring. We test the self-tuning statistical algorithms in a human primary T-cell activation assay in flow using nuclear factor of activated T cells (NFAT) translocation as a readout and readily achieve an average Z′ of 0.55 and strictly standardized mean difference of 13 with standard phorbol myristate acetate/ionomycin induction. To implement the tests, we routinely load 4 µL samples and can readout 3000 to 9000 independent conditions from 15 mL of primary human blood (buffy coat fraction). We conclude that the new technology will support primary-cell protein-localization assays and “on-the-fly” data scoring at a sample throughput of more than 100,000 wells per day and that it is, in principle, consistent with a primary pharmaceutical screen. | Parallel Microfluidic Cytometer (PMC), Phorbol Myristate Acetate/Ionomycin Induction, T-cell Activation |
“Assembly and Encapsulation of Aluminum NP's within AP/NC Matrix and their Reactive Properties” | H. Wang, R. J. Jacob, J. B. DeLisio, M. R. Zachariah | Combustion and Flame, Volume 180, June 2017, Pages 175–183 | Aluminum nanoparticles (Al NPs) are commonly employed as fuel supplement to increase the energy density of propellants. However, due to the highly agglomerated state of the NPs and significant pre-combustion sintering, ignition and combustion are not as facile as they could be. In this work, we employed a spray approach to generate near monodisperse microparticles of Al NP's encapsulated within ammonium perchlorate (AP) and a binder (nitrocellulose (NC)) The results show that Al/AP/NC composites have an ignition temperature (∼700 K), which is significantly lower than Al melting point (∼933 K). The reactivity of Al/AP/NC composites was also tested in a confined cell where we find that although the peak pressure for Al/AP/NC is comparable to that of physically mixed Al/CuO nanothermite, the impulse generated is more than two times higher. The measured flame temperature of Al/AP/NC composites were as high as 2800 K, which is ∼500 K higher than Al/AP composites without NC. Furthermore, the potential mechanism for the early ignition of these composites were investigated. It is proposed that gaseous acid released from AP could play an important role in weakening the protective oxide shell on Al nanoparticles which could subsequently lead to the reaction of Al in the high-pressure oxygenated environment at lower temperature. | Aluminum Nanoparticles, Al NP, Combustion |
“Incomplete Reactions in Nanothermite Composites” | R. J. Jacob, D. L. Ortiz-Montalvo, K. R. Overdeep, T. P. Weihs, M. R. Zachariah | Journal of Applied Physics, Volume 121, Issue 5 > 10.1063/1.4974963 | Exothermic reactions between oxophilic metals and transition/post transition metal-oxides have been well documented owing to their fast reaction time scales (≈10 μs). This article examines the extent of the reaction in nano-aluminum based thermite systems through a forensic inspection of the products formed during reaction. Three nanothermite systems (Al/CuO, Al/Bi2O3, and Al/WO3) were selected owing to their diverse combustion characteristics, thereby providing sufficient generality and breadth to the analysis. Microgram quantities of the sample were coated onto a fine platinum wire, which was resistively heated at high heating rates (≈105 K/s) to ignite the sample. The subsequent products were captured/quenched very rapidly (≈500 μs) in order to preserve the chemistry/morphology during initiation and subsequent reaction and were quantitatively analyzed using electron microscopy and focused ion beam cross-sectioning followed by energy dispersive X-ray spectroscopy. Elemental examination of the cross-section of the quenched particles shows that oxygen is predominantly localized in the regions containing aluminum, implying the occurrence of the redox reaction. The Al/CuO system, which has simultaneous gaseous oxygen release and ignition (TIgnition ≈ TOxygen Release), shows a substantially lower oxygen content within the product particles as opposed to Al/Bi2O3 and Al/WO3 thermites, which are postulated to undergo a condensed phase reaction (TIgnition ≪ TOxygen Release). An effective Al:O composition for the interior section was obtained for all the mixtures, with the smaller particles generally showing a higher oxygen content than the larger ones. The observed results were further corroborated with the reaction temperature, obtained using a high-speed spectro-pyrometer, and bomb calorimetry conducted on larger samples (≈15 mg). The results suggest that thermites that produce sufficient amounts of gaseous products generate smaller product particles and achieve higher extents of completion. | Calorimetry, Thermites , Nanothermite Systems |
“In Situ, Fast, High-Temperature Synthesis of Nickel Nanoparticles in Reduced Graphene Oxide Matrix” | Y. Li, Y. Chen, A. Nie, A. Lu, R. J. Jacob, T. Gao, J.Song, J. Dai, J. Wan, G. Pastel, M. R. Zachariah, R. S. Yassar, L. Hu | Advanced Energy Materials, 2017 DOI: 10.1002/aenm.201601783 | For the first time, a fast heating–cooling process is reported for the synthesis of carbon-coated nickel (Ni) nanoparticles on a reduced graphene oxide (RGO) matrix (nano-Ni@C/RGO) as a high-performance H2O2 fuel catalyst. The Joule heating temperature can reach up to ≈2400 K and the heating time can be less than 0.1 s. Ni microparticles with an average diameter of 2 µm can be directly converted into nanoparticles with an average diameter of 75 nm. The Ni nanoparticles embedded in RGO are evaluated for electro-oxidation performance as a H2O2 fuel in a direct peroxide–peroxide fuel cell, which exhibits an electro-oxidation current density of 602 mA cm−2 at 0.2 V (vs Ag/AgCl), ≈150 times higher than the original Ni microparticles embedded in the RGO matrix (micro-Ni/RGO). The high-temperature, fast Joule heating process also leads to a 4–5 nm conformal carbon coating on the surface of the Ni nanoparticles, which anchors them to the RGO nanosheets and leads to an excellent catalytic stability. The newly developed nano-Ni@C/RGO composites by Joule heating hold great promise for a range of emerging energy applications, including the advanced anode materials of fuel cells. | Nanoparticles, Graphene, Reduced Graphene Oxide Matrix, RGO |
“Development of Transverse beam and Shape Monitor for Integrable Optics Test Accelerator Based on Photomultiplier Tube Array” | Nadezna Afonkina | 2016 Optical Society of America | The report is dedicated to development and testing of a BPSM (Beam Position and Shape Monitor) for IOTA (Integrable Optics Test Accelerator) during summer internship at Fermi National Accelerator Laboratory (Fermilab). BPSM is based on 64-channel Photomultiplier tube (PMT) array Hamamatsu H7546B. Design with 8 of 64 channels is described in detail. Response, sensitivity and response speed test results are provided. Aspects of BPSM’s signal digitization and future development and commissioning are discussed. | Detectors, Arrays, Photomultipliers, Nondestructive Testing, Ultrafast Devices, Synchrotron Radiation |
“Novel Laser-Processed CsI:Tl Detector for SPECT” | H. Sabet, L. Bläckberg, D. Uzun-Ozsahin, G. El-Fakhri | Medical Physics (Lancaster), ISSN 0094-2405, Vol. 43, no 5, 2630-2638 p. | The aim of this work is to demonstrate the feasibility of a novel technique for fabrication of high spatial resolution CsI:Tl scintillation detectors for Single Photon Emission Computed Tomography systems. The scintillators are fabricated using laser-induced optical barriers (LIOB) technique to create optical micro-structures (or optical barriers) inside the CsI:Tl crystal bulk. The laser processed CsI:Tl crystals are 3, 5, and 10 mm in thickness. In this work we focus on the simplest pattern of optical barriers in that the barriers are created in the crystal bulk to form pixel-like patterns resembling mechanically pixelated scintillators. The monolithic CsI:Tl scintillator samples are fabricated with optical barrier patterns with 1.0x1.0 mm2 and 0.625x0.625 mm2 pixels. Experiments were conducted to characterize the fabricated arrays in terms of pixel separation and energy resolution. A 4x4 array of multi-pixel photon counter (MPPC) was used to collect the scintillation light in all the experiments. | Single Photon Emission Computed Tomography, SPECT, CsI:Tl, Pixelated Scintillators |
“A New DOI Detector Design Using Discrete Crystal Array with Depth-Dependent Reflector Patterns and Single-Ended Readout” | S. J. Lee, C. Lee, J. Kang, Y. H. Chung | Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | We developed a depth of interaction (DOI) positron emission tomography (PET) detector using depth-dependent reflector patterns in a discrete crystal array. Due to the different reflector patterns at depth, light distribution was changed relative to depth. As a preliminary experiment, we measured DOI detector module crystal identification performance. The crystal consisted of a 9×9 array of 2mm x 2mm x 20mm lutetium-yttrium oxyorthosilicate (LYSO) crystals. The crystal array was optically coupled to a 64-channel position-sensitive photomultiplier tube with a 2mm x 2mm anode size and an 18.1mm x 18.1mm effective area. We obtained the flood image with an Anger-type calculation. DOI layers and 9×9 pixels were well distinguished in the obtained images. Preclinical PET scanners based on this detector design offer the prospect of high and uniform spatial resolution. | PET, LYSO, Depth of Interaction, DOI, Reflector Patterns, Light Distribution |
“High Speed, Low Dose, Intelligent X-ray Cargo Inspection” | A. Arodzero, S. Boucher, J. Hartzell, S. V. Kutsaev, R. C. Lanza, V. Palermo, S. Vinogradov, V. Ziskin | 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference, San Diego, CA | The security market requirements for high throughput rail cargo radiography inspection systems include better than 5 mm line pair imaging resolution, penetration beyond 400 mm steel equivalent, scan speeds of up to 60 km/h, material discrimination (four groups of Z) in 100 % of cargo at speeds reaching 45 km/h, low dose and small radiation exclusion zone. In order to achieve these requirements, which cannot be met by conventional dual energy radiography systems, a team lead by RadiaBeam Technologies, LLC (RBT) has initiated a research into new radiography methods and imaging detector materials with the goal of developing an Adaptive Railroad Cargo Inspection System (ARCIS). The ARCIS technical concept relies on linac-based, adaptive, ramped energy source of packets of short X-ray pulses sampled by a new type of fast X-ray detectors with rapid hardware processing for intelligent linac control, and advanced radiography image processing and material discrimination analysis. The following ARCIS key enabling technologies overcome the limitations of the conventional dual energy interlaced cargo inspection systems: • Multi-energy material discrimination in a single scan line provided by packets of short pulses from an X-ray source with end-point energy ramp up (> 1 MHz rate of energy switching); • Real-time intelligent setting of packet’s maximum energy depend on X-ray attenuation in cargo; • Fast Scintillation-Cherenkov detectors with reduced sensitivity to scatter radiation; • Detector readout with Silicon Photomultiplier (SiPM) provides time-resolving of short X-ray pulses; • Self-control adaptive dynamic adjustment of SiPM responsivity in detector channel for increased dynamic range. | Dual Energy LINAC, Adaptive Responsivity Control, SiPM, X-Ray Imaging, ARCIS, Scintillation-Cherenkov Detectors |
“Design and Development of Hard X-ray Imaging Detector Using Scintillator and Si Photomultiplier” | S. K. Goyal, Amisha P. Naik, Mithun N. P. S., S. V. Vadawale, Y. B. Acharya, A. R. Patel, T. Ladiya, Niranjan M. Devashrayee | Proc. SPIE 9915, High Energy, Optical, and Infrared Detectors for Astronomy VII, 99152J (July 27, 2016); doi:10.1117/12.2232234 | There are various astrophysical phenomena which are of great importance and interest such as stellar explosions, Gamma ray bursts etc. There is also a growing interest in exploring the celestial sources in hard X-rays. High sensitive instruments are essential to perform the detailed studies of these cosmic accelerators and explosions. Hard X-ray imaging detectors having high absorption efficiency and mm spatial resolution are the key requirements to locate the generation of these astrophysical phenomenon. We hereby present a detector module which consists of a single CsI scintillation detector of size 15 x 15 x 3 mm3. The photon readout is done using an array of Silicon Photomultipliers (SiPMs). SiPM is a new development in the field of photon detection and can be described as 2D array of small (hundreds of μm2) avalanche photodiodes. We have achieved a spatial resolution of 0.5 mm with our initial setup. By using the array of these detector modules, we can build the detector with a large sensitive area with a very high spatial resolution. This paper presents the experimental details for single detector module using CsI (Tl) scintillator and SiPM and also presents the preliminary results of energy and position measurement. The GEANT4 simulation has also been carried out for the same geometry. | Hard X-rays, CsI (Tl) scintillator, SiPM |
“Methods and Systems for Coherent Raman Scattering” | C. W. Freudiger, J. K. Trautman | United States Patent Application 20160178439, June 23, 2016 | Systems and methods employing Coherent Raman Scattering (CRS), e.g., Coherent anti-Stokes Raman Spectroscopy (CARS) and/or Stimulated Raman Scattering (SRS) are provided. Systems and methods for performing flow cytometry, imaging and sensing using low-resolution CRS are also provided. | Coherent Raman Scattering, CRS, Coherent Anti-Stokes Raman Spectroscopy (CARS), Stimulated Raman Scattering (SRS), Flow Cytometry |
“Improving the Optical Yield of a Portable Plastic-Scintillator-Based Muon Tomography System” | K. Moats | Contract Report, DRDC-RDDC-2016-C142, April 2016 | A portable muon tomography system could be used to image suspect Special Nuclear Material (SNM) objects that are approximately 1 m3 or smaller. The work in this report focuses on the simulation and laboratory studies of this system for use by the Canadian Armed Forces (CAF). The main challenge for image reconstruction in a portable muon scattering tomography is achieving a precise angular resolution. In order to do so, the optical yield must be improved over that from the much larger CRIPT experiment. This work studied seven materials that could be used as optical couplers, inserted between the plastic triangular scintillating bars and the wavelength shifting fibres. This would serve to minimize losses of scintillation photons as they are channeled by the wavelength shifting fibres via total internal reflection. Test data for this system using 90Sr, 137Cs and cosmic ray muon sources was collected at DRDC Ottawa Research Centre and was analyzed by writing C++ code using the ROOT analysis package. An optical simulation of the same system was performed using the C++ Geant4 framework as a means to validate the experimental results using cosmic ray muons. Although the Geant4 results for some optical couplers agree quite well with experiment, there are some discrepancies for the other optical couplers. Whether these discrepancies are due to limitations in the simulation or systematic errors in the experimental setup is currently being investigated. Once the best optical coupler is determined, future simulations will allow us to optimize design of the portable system and build a prototype for scanning 1 m3 objects, which is currently in the preliminary design stages. Improving the muon position resolution will allow smaller muon trackers without sacrificing angular resolution. This work will allow us to determine if a plastic scintillator based portable muon tomography system is feasible and if it will meet user requirements for use in the field. | Muon Tomography, Plastic Scintillator, SNM |
“Novel laser-processed CsI: Tl detector for SPECT” | H. Sabet, L. Bläckberg, D. Uzun-Ozsahin and G. El-Fakhri | Medical Physics, 2016 | Purpose: The aim of this work is to demonstrate the feasibility of a novel technique for fabrication of high spatial resolution CsI:Tl scintillation detectors for single photon emission computed tomography systems. Methods: The scintillators are fabricated using laser-induced optical barriers technique to create optical microstructures (or optical barriers) inside the CsI:Tl crystal bulk. The laser-processed CsI:Tl crystals are 3, 5, and 10 mm in thickness. In this work, the authors focus on the simplest pattern of optical barriers in that the barriers are created in the crystal bulk to form pixel-like patterns resembling mechanically pixelated scintillators. The monolithic CsI:Tl scintillator samples are fabricated with optical barrier patterns with 1.0 × 1.0 mm2 and 0.625 × 0.625 mm2 pixels. Experiments were conducted to characterize the fabricated arrays in terms of pixel separation and energy resolution. A 4 × 4 array of multipixel photon counter was used to collect the scintillation light in all the experiments. Results: The process yield for fabricating the CsI:Tl arrays is 100% with processing time under 50 min. From the flood maps of the fabricated detectors exposed to 122 keV gammas, peak-to-valley (P/V) ratios of greater than 2.3 are calculated. The P/V values suggest that regardless of the crystal thickness, the pixels can be resolved. Conclusions: The results suggest that optical barriers can be considered as a robust alternative to mechanically pixelated arrays and can provide high spatial resolution while maintaining the sensitivity in a high-throughput and cost-effective manner. | SPECT, CsI:Tl, Pixellated Scintillator |
“Mapping Multidimensional Electronic Structure and Ultrafast Dynamics with Single-Element Detection and Compressive Sensing” | Austin P. Spencer, Boris Spokoyny, Supratim Ray, Fahad Sarvari, Elad Harel | Nature Communications, 7:10434 doi: 10.1038/ncomms10434 (2016) | Compressive sensing allows signals to be efficiently captured by exploiting their inherent sparsity. Here we implement sparse sampling to capture the electronic structure and ultrafast dynamics of molecular systems using phase-resolved 2D coherent spectroscopy. Until now, 2D spectroscopy has been hampered by its reliance on array detectors that operate in limited spectral regions. Combining spatial encoding of the nonlinear optical response and rapid signal modulation allows retrieval of state-resolved correlation maps in a photosynthetic protein and carbocyanine dye. We report complete Hadamard reconstruction of the signals and compression factors as high as 10, in good agreement with array-detected spectra. Single-point array reconstruction by spatial encoding (SPARSE) Spectroscopy reduces acquisition times by about an order of magnitude, with further speed improvements enabled by fast scanning of a digital micromirror device. We envision unprecedented applications for coherent spectroscopy using frequency combs and super-continua in diverse spectral regions. | Hadamard Reconstruction, 2D Spectroscopy |
“MEBT and D-Plate Control System Status of the Linear IFMIF Prototype Accelerator” | J. Calvo, D. Jimenez-Rey, E. Molina Marinas, J. Molla, I. Podadera | Proceedings of ICALEPCS2015, Melbourne, Australia Pre-Press Release 23-Oct-2015 11:00MOPGF045 | Linear IFMIF Prototype Accelerator (LIPAc), Rokkasho, Japan, comprises a succession of devices and systems that accelerate a deuteron beam up to 9 MeV with a current of 125 mA, generating a power of 1.125 MW, and transport it up to a beam dump. The beam power becomes critical from the point of view of losses; even tiny losses must be avoided. This fact, and the complexity of the accelerator operation, requires a coherent strategy when designing, commissioning and optimizing the accelerator control system, specifically focused in the control systems of the Medium Energy Beam Transport (MEBT) and the Diagnostic Plate (DP, a movable set of diagnostics). Both systems are essential to validate the performance of the accelerator and particularly the ion source, Radio Frequency (RF) and Radio Frequency Quadrupole (RFQ) systems. This contribution will describe the recent advances in the control architectures and the EPICS based developments achieved in MEBT for the motion control of bunchers and scrapers, control of the power supplies in quadrupoles and steerers, and refrigeration and vacuum. Besides, control of fluorescence profile monitors (FPMs) in the D-Plate is displayed. | IFMIF Prototype, Deuteron, Accelerator Physics |
“Continuous Flow Real-Time PCR Device Using Multi-Channel Fluorescence Excitation and Detection” | Andrew C. Hatch, Tathagata Ray, Kelly Lintecum, Cody Youngbull | Lab on a Chip, Issue 3 2014 | High throughput automation is greatly enhanced using techniques that employ conveyor belt strategies with un-interrupted streams of flow. We have developed a 'conveyor belt' analog for high throughput real-time quantitative Polymerase Chain Reaction (qPCR) using droplet emulsion technology. We developed a low power, portable device that employs LED and fiber optic fluorescence excitation in conjunction with a continuous flow thermal cycler to achieve multi-channel fluorescence detection for real-time fluorescence measurements. Continuously streaming fluid plugs or droplets pass through tubing wrapped around a two-temperature zone thermal block with each wrap of tubing fluorescently coupled to a 64-channel multi-anode PMT. This work demonstrates real-time qPCR of 0.1-10 uL droplets or fluid plugs over a range of 7 orders of magnitude concentration from 1 x 10^1 to 1 x 10^7. The real-time qPCR analysis allows dynamic range quantification as high as 1 x 10^7 copies per 10 uL reaction, with PCR efficiencies within the range of 90-110% based on serial dilution assays and a limit of detection of 10 copies per rxn. The combined functionality of continuous flow, low power thermal cycling, high throughput sample processing, and real-time qPCR improves the rates at which biological or environmental samples can be continuously sampled and analyzed. | Polymerase Chain Reaction, Multi-Channel Fluorescence |
“Modelling of Light Photons Detection in Scintillation Camera” | S.F. Md Ali, D. Xianling, A.S. Muhammad Noor, F.Z Rokhani, S. Hashim, M.I Saripan | Signal and Image Processing Applications (ICSIPA), 2013 IEEE International Conference on Signal and Image Processing Applications, 8 October 2013 | Silicon photomultiplier (SiPM) technology have been introduced recently for photon detection. This type of detector offers various advantages compared to conventional photomultiplier tubes (PMTs). SiPMs are smaller in size and thus consumes less space. Several research efforts have been conducted using SiPMs for image acquisition in the field of medical imaging. The aim of this research is to model the intrinsic resolution of a scintillation camera using SiPM detectors. Experiments are conducted to determine the optimum distance between the light source and the SiPM detector to obtain an intrinsic resolution of 3.7 mm. The resolution is based on previous research using Toshiba GCA 7100A platform with Sodium Iodide (NaI) scintillator (40 x 40 x 0.9525 cm3). Results revealed that the SiPM needs to be placed at a distance of 14.36 mm from the light source to represent the scintillation camera intrinsic resolution. It is concluded that the SiPM detector can be used to model the current scintillation camera's intrinsic resolution and have a huge potential to replace the current photomultiplier tube detector. | SiPM, Sodium Iodide, Medical Imaging, Scintillation Camera |
“SPADnet:Embedded Coincidence in a Smart Sensor Network for PET Applications” | C. Bruschini, E. Charbon, C. Veerappan, L.H.C. Braga, N. Massari, M. Perenzoni, L. Gasparini, D. Stoppa, R. Walker, A. Erdogan, R.K. Henderson, S. East, L. Grant, B. Jatekos, F. Ujhelyi, G. Erdei, E. Lorincz, L. Andre, L. Maingault, V. Reboud, L. Verger, E. Grosd'Aillon, P. Major, Z. Papp, G. Nemeth | Nuclear Instruments and Methods in Physics Research A, 734 (2014) 122-126 | In this paper we illustrate the core technologies at the basis of the European SPADnet project, and present the corresponding first results. SPADnet is aimed at a new generation of MRI-compatible, scalable large area image sensors, based on CMOS technology, that are networked to perform gamma-ray detection and coincidence to be used primarily in (Time-of-Flight) Positron Emission Tomography (PET). The project innovates in several areas of PET systems, from optical coupling to single-photon sensor architectures, from intelligent ring networks to reconstruction algorithms. In addition, SPADnet introduced the first computational model enabling study of the full chain from gamma photons to network coincidence detection through scintillation events, optical coupling, etc. | Time-of-Flight PET, SPADnet |
“Construction and Testing of a Positron Emission Tomography Demonstrator” | Tiziana Zedda | Tampere University of Technology, 5 June 2013 | In this thesis we present the Avantomography demonstrator, which is being implemented and tested at Tampere University of Technology (Tampere, Finland). We also describe the first tests performed with it and the obtained results. The final aim of this master thesis is the energy calibration of the scintillating crystals and the electronic chain for data acquisition. This new small Positron Emission Tomography (PET) demonstrator follows the recent innovations presented by the AX-PET group , at CERN. This is the first functioning version of a prototype of a light and compact PET scanner. The novel geometry, used to build the Avantomography demonstrator, is based on scintillating crystals and wavelength shifting (WLS) plastic strips, allowing high resolution and high sensitivity at the same time. The device consists in two small and compact modules, with two different adjustable parts inside. Each detector module is built up from long scintillator bars placed in the trans-axial plane and orthogonal WLS strip arrays. Preliminary tests with a standard positron emitter source has been performed in order to test the acquisition chain and to calibrate the demonstrator. First test has been performed measuring the intrinsic radioactivity of the scintillating crystals. For a complete calibration of one crystal, a test with a linear positron emitter source has been performed at the Tampere University Hospital (Tampere, Finland). From these measurements the spectra of different energy peaks are acquired and plotted. Using a dedicate MATLAB code, different Gaussian fits are calculated to find the position of each peak. With these values a 3-parameters fitting curve has been evaluated in order to obtain the non linear curve for the energy calibration. Furthermore a first evaluation of the energy resolution has been calculated starting from the acquired data. With its compact and light geometry, high resolution and high sensitivity this detector has a promising layout as a preclinical PET scanner. | PET, Avantomography, AX-PET, Wavelength Shifting, Scintillator |
“Automated Platform for Multiparameter Stimulus Response Studies of Metabolic Activity at the Single-Cell Level” | Shashanka P. Ashili, Laimonas Kelbauskas, Jeff Houkal, Dean Smith, Yanqing Tian, Cody Youngbull, Haixin Zhu, Yasser H. Anis, Michael Hupp, Kristen B. Lee, Ashok V. Kumar, Juan Vela, Andrew Shabilla, Roger H. Johnson, Mark R. Holl, Deirdre R. Meldrum | SPIE Proceedings, Volume 7929, BioMEMS and Medical Microsystems 14 February 2011 | We have developed a fully automated platform for multiparameter characterization of physiological response of individual and small numbers of interacting cells. The platform allows for minimally invasive monitoring of cell phenotypes while administering a variety of physiological insults and stimuli by means of precisely controlled microfluidic subsystems. It features the capability to integrate a variety of sensitive intra- and extra-cellular fluorescent probes for monitoring minute intra- and extra-cellular physiological changes. The platform allows for performance of other, post- measurement analyses of individual cells such as transcriptomics. Our method is based on the measurement of extracellular metabolite concentrations in hermetically sealed ~200-pL microchambers, each containing a single cell or a small number of cells. The major components of the system are a) a confocal laser scan head to excite and detect with single photon sensitivity the emitted photons from sensors; b) a microfluidic cassette to confine and incubate individual cells, providing for dynamic application of external stimuli, and c) an integration module consisting of software and hardware for automated cassette manipulation, environmental control and data collection. The custom-built confocal scan head allows for fluorescence intensity detection with high sensitivity and spatial confinement of the excitation light to individual pixels of the sensor area, thus minimizing any phototoxic effects. The platform is designed to permit incorporation of multiple optical sensors for simultaneous detection of various metabolites of interest. The modular detector structure allows for several imaging modalities, including high resolution intracellular probe imaging and extracellular sensor readout. The integrated system allows for simulation of physiologically relevant microenvironmental stimuli and simultaneous measurement of the elicited phenotypes. We present details of system design, system characterization and metabolic response analysis of individual eukaryotic cells. | Fluorescent Probe, Microfluidics, Extracellular Metabolite |
Hyperspectral Fluorescence Lifetime Lidar for Geological Exploration” | Bruno Bourliaguet, Nicolas Hô, Francis Généreux, Frédéric Émond, Félix Cayer, François Babin | SPIE Proceedings, Volume 7478, Geological Remote Sensing, 31 August 2009 | We have developed a small, relatively lightweight and efficient lidar instrument for remotely detecting and classifying minerals. The system is based on a pulsed, eye-safe, diode pumped Nd:YAG laser, tripled (355nm) or quadrupled (266nm), for UV excitation of minerals, which then fluoresce with a typical spectrum and lifetime. Fluorescence is detected through a telescope / filter / fiber bundle / spectrograph / multi-channel detector system capable of photon counting. Transmission and detection efficiency have been optimized to reduce the need for high optical excitation energy. Detection electronics are based on gated charge integration using a multi-anode photomultiplier tube. Spectra shown are measured in the 420 to 720 nm visible range with 355 nm laser excitation. Results show that it is relatively easy to distinguish between vegetation and non-vegetation spectra using lifetime data. Lifetime of vegetation is relatively short when compared to the mineral samples investigated. Although results shown are measured in a controlled environment on the ground, the system is being developed for eventual use in a low altitude airborne application. System parameters are presented and upgrade paths are discussed. | LIDAR, Nd:YAG Laser,Fluorescence, Photon Counting |
“Optimization of the Angle between Detector Modules in a Dual-Head Cardiac SPECT” | Su Jung An, Hyun-Il Kim, Chae Young Lee, Woo Jin Jo, Yong Hyun Chung | Journal of the Korean Physical Society, January 2013, Volume 62, Issue 1, pp 147-151 | In recent years, dedicated cardiac single photon emission computed tomography (SPECT) systems have been undergoing a profound change in design with multiple detectors and various angles between the modules to improve the sensitivity and the resolution by reducing the distance between the heart and the detector. The performance of a dual-head cardiac SPECT for small-animal imaging was characterized as a function of the angle between two detector heads by using GATE simulations, and simulation data were validated with experimental results. Each detector head consists of 50x50x6 mm^3 NaI(Tl) optically coupled to a Hamamatsu H8500 position sensitive photomultiplier (PSPMT) and a low-energy high-resolution parallel-hole collimator (LEHR, septal thickness: 0.2 mm, diameter: 1.9 mm). The distance between the collimator surface and the center of rotation was set as 20, 20, 20, 25, or 31.5 mm for 70°, 80°, 90°, 100°, or 110°, respectively, based on a 40-mm field of view (FOV). A point source and a rat cardiac phantom of Tc-99m in scattering media were simulated. Projection data were acquired for 180 angular views in steps of 2° and were reconstructed by using a filtered back-projection algorithm. Results demonstrated that the angle between the detector heads did not make a big difference in the image quality when scattering media were not presented, but the dual heads in the 80° geometry provided the best spatial resolution in the cardiac phantom study. The peak-to-valley ratio between the myocardial wall and the cavity was measured as 1.87, 11.01, 3.28, 3.40, or 2.46 for 70°, 80°, 90°, 100°, or 110°, respectively. Experiments were performed with a dual-head SPECT in the 80° geometry, and the results agreed well with these from the simulations. In this study, the impact of the angle between dual detector heads on the imaging performance was evaluated, and the optimal angle was derived for a dedicated cardiac SPECT. | Dual-Head SPECT, PSPMT, NaI(Tl), Hamamatsu H8500 |
“A Method to Remove Residual Signals in Fibre Optic Luminescence Dosimeters” | J. J. Lee, P. Z. Y. Liu, D. R. McKenzie, N. Suchowerska | Physics in Medicine and Biology, Volume 58, Number 5 | Whenever a fibre optic is used to convey a light signal through a radiation field, it is likely that an unwanted background signal will arise from Cerenkov or fluorescent light which will contaminate the signal. In luminescence dosimetry of high energy beams, when a fibre optic is used to convey the signal from the radiation field to the detector, Cerenkov light is the dominant contributor to the background signal and must be corrected for. In this work, a novel method is demonstrated to separate the signal from the unwanted background. A remotely operated shutter is used to block the signal, allowing the residual background in the fibre optic to be quantified. This background is subtracted from the total measurement acquired in a subsequent irradiation, enabling the luminescence signal to be extracted. Two types of shutter mechanism are considered: an electro-mechanical device to intercept the light path and an LCD device to block the light by cross-polarization. Both shutters were characterized and incorporated into a fibre optic dosimetry system used to measure the radiation dose produced by external beam radiation linear accelerators. The dosimeter using each of the shutters in turn was exposed to a 6 MV photon beam to determine their performance, including the measurement of field size dependent output factors. The mechanical shutter determined the output factors to within 0.29% of those measured with an ionization chamber, whereas the LCD shutter gave results that deviated by up to 2.4%. The switching precision of both shutters was good with standard deviations of less than 0.25% and both were able to completely block the light signal when closed. The use of shutters could therefore be applied to any fibre optic based system to quantify and remove a reproducible background arising from any source including ambient, fluorescent and Cerenkov light. | Luminescence Dosimetry, Cerenkov Light, Fluorescence |
“Combined Gamma-Ray/Neutron Imaging System for Detecting Nuclear Material” | Lakshmi Soundara-Pandian, Jarek Glodo, James F. Christian, Robert Vinci, Andrey Gueorguiev, Chad Whitney, Erik B. Johnson, Kanai S. Shah, Michael R. Squillante | Radiation Monitoring Devices, Inc. 44 Hunt Street, Watertown, MA 02472 | The instrument, which is based on the new generation of scintillator materials that have the capability to discriminate gamma rays from neutrons, will simultaneously image gamma rays and neutrons. Detecting and imaging neutrons provides the ability to detect sources that are heavily shielded for gamma rays. Since few materials emit neutrons, the presence of neutrons in the image is a strong indicator of the presence of fissile material. The system would also be useful for active interrogation. This paper will discuss camera design and examine the trade-offs needed to optimize both the gamma ray and neutrons imaging systems and present measured gamma and neutron images. | Scintillator, Gamma Ray, Neutrons |
“New Tests of Fluorescence Beam Profilers for the Linear IFMIF Prototype Accelerator (LIPAC) Using 9MeV Deuteron Beams” | J. M. Carmona, I. Podadera, J. García López, M.C. Jiménez-Ramos | Proceedings of BIW2012, Newport News, Virginia, USA, TUPG028 | LIPAc prototype accelerator will be a 9 MeV, 125 mA continuous wave (CW) deuteron accelerator, focused on validating the technology that will be used in the future IFMIF facility. In this high power accelerator (1.125 MW), interceptive profilers are forbidden during the nominal operation. In the quest of non interceptive beam transverse profilers required for LIPAc, two prototypes based on the fluorescence of residual gas have been developed by CIEMAT. New experimental tests using 9 MeV deuterons were performed at CNA using the prototypes. Tests include injection of hydrogen, injection of nitrogen for comparison with previous results and a beam steering experiment. Hence, a brief description of the beam transverse profile prototypes together with a summary of the improved new measurements are presented. | LIPAc, Deuteron Accelerator, IFMIF, CIEMAT, Beam Transverse Profiler |
“Measurements of Noninterceptive Fluorescence Profile Monitor Prototypes Using 9 MeV Deuterons” | J. M. Carmona, I. Podadera, A. Ibarra, A. Bocci, M.C. Jiménez-Ramos, J. García López, Z. Abou-Haïdar, M. A. G. Alvarez, B. Fernández | Physical Review Special Topics - Accelerators and Beams, Vol. 15, Issue 7 | Two types of noninterceptive optical monitors, based on gas fluorescence, have been designed for use on the Linear IFMIF Prototype Accelerator (LIPAc) that is currently under development (a 125 mA, 9 MeV, 175 MHz continuous wave deuteron beam). These diagnostics offer a technique to characterize the transverse beam profile for medium to high current hadron beams, without intercepting the beam core. This paper reports on beam tests using the prototype monitors developed for LIPAc. Tests were carried out at an experimental line of the Centro Nacional de Aceleradores cyclotron, using 9 MeV deuterons with beam currents from 0.4 to 40uA. In addition, transverse beam profile measurements were performed under high background radiation (e.g. gamma dose rate up to 83mSv/h). Preliminary cross-checks with different profilers, as well as a systematic scan of beam current and vacuum pressures and tests with different injected gases (nitrogen and xenon) have been performed. In this work, we present a brief description of the experimental setup and the first measurements obtained with these prototype profilers plus a discussion of the first analysis of the background signal in a detector as a function of radiation background. | LIPAc, Deuteron Accelerator, IFMIF, CIEMAT, Noninterceptive Optical Monitors, Hadron Beam |
“Gamma Camera with a Two-Layer Diverging-Slat Collimator for Radioisotope Monitoring” | Hyun-Il Kim, Cheol-Ha Baek, Su Jung An, Sung-Woo Kwak, Yong Hyun Chung | Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 698, 11 January 2013 | The purpose of this study was to develop and evaluate a gamma camera with a newly designed diverging collimator for monitoring radiation fields in nuclear medicine. Simulations using the Geant4 Application for Tomographic Emission (GATE) were performed to model the gamma camera system designed to monitor Tc-99m radioactive isotopes usually used in nuclear medicine. A gamma camera consists of a diverging collimator, a CsI(Na) scintillation crystal with dimensions of 50.0 mm by 50.0 mm by 6.0 mm and Hamamatsu H8500 PSPMT. The diverging collimator is composed of two layers of diverging slats stacked directly above each other, and the front layer is rotated by 90 degrees with respect to the back layer. The point source at different positions was simulated, and the optimal slat thickness and slat height were determined by evaluating the spatial resolution and sensitivity. The slat thickness is 1.0 mm, the slat height is 40.0 mm and the angle of slats ranges from 0 to 22.5 degrees. The front and back layers are composed of 40 and 18 slats, respectively, to achieve equal spatial resolution in the x and y directions. The diverging collimator improves the uniformity of the spatial resolution and sensitivity across the field of view and the count rate better than the pinhole collimator. Experimental measurements were performed, and the results agreed well with simulations in terms of spatial resolution and sensitivity. The results demonstrated that the two-layer diverging-slat collimator is suitable for large area monitoring of the radiation fields. | Hamamatsu H8500 PSPMT, CsI(Na) Scintillator, Gamma Camera, Tc-99m |
“Light Propagation in Multimoded Square Hollow Waveguides” | Pourandokht Naseri, David R McKenzie, Paul Liu, Simon Fleming, Natalka Suchowerska | Journal of Optics, Vol. 14 Number 10 | The irradiance – distance relation for light propagation in multimoded hollow waveguides is calculated from theory and compared with measurement for visible light. These are the first measurements of this relation for square waveguides and the first for round waveguides for visible light. The square waveguides had either silvered glass surfaces or uncoated PMMA surfaces. A geometric optics method based on image formation in a kaleidoscope is used for calculations. The measurements agreed with the predictions of theory in all cases. The loss is not described by a fixed value of an attenuation coefficient as the angular divergence of the light changes with distance. At larger distances the logarithm of the irradiance is linearly dependent on the logarithm of distance, regardless of material type, surface properties and waveguide cross section. The silvered square waveguide shows the lowest measured attenuation while PMMA square waveguides constructed without any special surface preparation performed almost as well as silvered round tubes sourced commercially. The surface roughness present in the silver coating of commercially sourced round tubes compromised their performance. An array of square PMMA waveguides was used to demonstrate an application for signal transport in megavoltage radiation fields for profiling a medical radiation beam and measuring the variation of dose rate with depth in water. | Multimoded Hollow Waveguides |
“Characterization of MRI-Compatible PET Detector Modules by Optical Excitation of the Scintillator Material” | B. Játékos, Z. Kolozsi, E. Lörincz, F. Ujhelyi, A. Barócsi, G. Erdei | Proceedings of SPIE, Vol. 8439, 84391R | In the field of biomedical imaging there is a strong interest in combining modalities of positron emission tomography (PET) and magnetic resonance imaging (MRI). An MRI-compatible PET detector module has to be insensitive to the magnetic field that is why it needs to incorporate avalanche photodiodes (APD) or silicon photomultipliers (SiPM). We propose a new purely optical characterization method for these devices where no nuclear source is needed. In our method we use LED sources for both the direct illumination of silicon sensors and fluorescent excitation of the scintillator material. With this method we can measure the response characteristic and uniformity of pixels in sensor arrays as well as the optical cross-talk between neighboring pixels. In the same experimental setup we can also emulate the pulse response of the detector module (i.e. light-spread over the sensor array from a point source in the scintillator material). We present the detailed construction of the experimental setup and analyze the benefits and drawbacks of this method compared to the nuclear measurements. The viability of the idea is proven through the characterization of a SiPM array and a block detector module based on it. | Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI), SiPM, Scintillator, Fluorescent Excitation |
“Hyperspectral Cytometry at the Single-Cell Level Using a 32-Channel Photodetector” | G. Grégori, V. Patsekin, B. Rajwa, J. Jones, K. Ragheb, C. Holdman, J. P. Robinson | Cytometry Part A, Volume 81A, Issue 1, pages 35-44, January 2012 | Despite recent progress in cell-analysis technology, rapid classification of cells remains a very difficult task. Among the techniques available, flow cytometry (FCM) is considered especially powerful, because it is able to perform multiparametric analyses of single biological particles at a high flow rate-up to several thousand particles per second. Moreover, FCM is nondestructive, and flow cytometric analysis can be performed on live cells. The current limit for simultaneously detectable fluorescence signals in FCM is around 8-15 depending upon the instrument. Obtaining multiparametric measurements is a very complex task, and the necessity for fluorescence spectral overlap compensation creates a number of additional difficulties to solve. Further, to obtain well-separated single spectral bands a very complex set of optical filters is required. This study describes the key components and principles involved in building a next-generation flow cytometer based on a 32-channel PMT array detector, a phase-volume holographic grating, and a fast electronic board. The system is capable of full-spectral data collection and spectral analysis at the single-cell level. As demonstrated using fluorescent microspheres and lymphocytes labeled with a cocktail of antibodies (CD45/FITC, CD4/PE, CD8/ECD, and CD3/Cy5), the presented technology is able to simultaneously collect 32 narrow bands of fluorescence from single particles flowing across the laser beam in <5 µs. These 32 discrete values provide a proxy of the full fluorescence emission spectrum for each single particle (cell). Advanced statistical analysis has then been performed to separate the various clusters of lymphocytes. The average spectrum computed for each cluster has been used to characterize the corresponding combination of antibodies, and thus identify the various lymphocytes subsets. The powerful data-collection capabilities of this flow cytometer open up significant opportunities for advanced analytical approaches, including spectral unmixing and unsupervised or supervised classification. | Flow Cytometry, Hamamatsu H7260, 32 Channel PMT, Fluorescence Spectroscopy |
“A Feasibility Study on the Use of Arrays of Discrete SiPMs for MR Compatible LYSO Readout using Monte Carlo Simulation” | P. Aguiara, A. Iglesias, B. Couce, C. Lois | Journal of Instrumentation, Volume 7, June 2012 | This paper shows a feasibility study on the use of discrete SiPMs to read out monolithic scintillator-based detectors for use in molecular imaging applications. Monte Carlo simulations are carried out in order to evaluate the basic performance of 8 x 8 arrays of discrete SiPMs with different PDE values and compare it to conventional 64 channel multi-anode PMT (MA-PMT) readout. A detailed optical transport model was incorporated into the Monte Carlo simulation and a detector module based on a monolithic scintillator crystal of 50 x 50 x 4 mm^3 coupled to a MA-PMT was built for experimental validation. The effect of the SiPM dynamic range was also investigated by including a model of the saturation effects into the optical transport simulation. The results show that a detector module based on an array of 8 x 8 discrete SiPM devices (3 x 3 mm^2 and PDE > 32%) is feasible as a replacement of a 64 channel MA-PMT in order to read out large monolithic crystals for MR-compatible gamma cameras. | SiPM, Scintillator, 64 channel MAPMT, gamma camera |
“Real-time Scintillation Array Dosimetry for Radiotherapy: The Advantages of Photomultiplier Detectors” | P. Z. Y. Liu, N. Suchowerska, P. Abolfathi, D. R. McKenzie | Medical Physics, Volume 39, Issue 4, Radiation Imaging Physics, 8 March 2012 | In this paper, a photomultiplier tube (PMT) array dosimetry system has been developed and tested for the real-time readout of multiple scintillation signals from fiber optic dosimeters. It provides array dosimetry with the advantages in sensitivity provided by a PMT, but without the need for a separate PMT for each detector element. The PMT array system consisted of a multianode PMT, a multichannel data acquisition system, housing and optic fiber connections suitable for clinical use. The reproducibility, channel uniformity, channel crosstalk, acquisition speed, and sensitivity of the PMT array were quantified using a constant light source. Its performance was compared to other readout systems used in scintillation dosimetry. An in vivo HDR brachytherapy treatment was used as an example of a clinical application of the dosimetry system to the measurement of dose at multiple sites in the rectum. The PMT array system was also tested in the pulsed beam of a linear accelerator to test its response speed and its application with two separate methods of Cerenkov background removal. The PMT array dosimetry system was highly reproducible with a measurement uncertainty of 0.13% for a 10 s acquisition period. Optical crosstalk between neighboring channels was accounted for by omitting every second channel. A mathematical procedure was used to account for the crosstalk in next-neighbor channels. The speed and sensitivity of the PMT array system were found be superior to CCD cameras, allowing for measurement of more rapid changes in dose rate. This was further demonstrated by measuring the dose delivered by individual photon pulses of a linear accelerator beam. The PMT array system has advantages over CCD camera-based systems for the readout of scintillation light. It provided a more sensitive, more accurate, and faster response to meet the demands of future developments in treatment delivery. | Dosimetry, PMT, Cerenkov Radiation, |
“Characterization of Low Energy Lu Background on Continuous LYSO Blocks” | C. Lois, P. Aguiar, B. Couce, A. Iglesias | Nuclear Science Symposium Conference Record (NSS/MIC), 2010 IEEE | The presence of the naturally occurring isotope 176Lu gives rise to background count rates in LSO/LYSO crystals to be used in PET and SPECT systems. The aim of this work is to measure 176Lu background count rates and its spatial distributions in a continuous LYSO block. Our results show that the low energy component of 176Lu background is related to partial energy deposition mainly produced near the crystal edge showing a hot-perimeter artifact. Furthermore, 176Lu background rate is observed to be 10 times lower for a 100-180 keV than for a 411-611 keV energy window. Our findings indicate that when using monolithic LYSO crystal blocks, 176Lu background is not expected to significantly deteriorate the performance of single photon detection systems. | PET, SPECT, 176Lu, LSO, LYSO |
“Measurement and Autocorrelation Analysis of Two-Dimensional Light-Scattering Patterns from Living Cells for Label-Free Classification” | Y. L. Pan, M. J. Berg, S. S. Zhang, H. Noh, H. Cao, R. K. Chang, G. Videen | Cytometry Part A, 79A: 284-292, 2011 | Optics and an ICCD are incorporated to record the two-dimensional angular optical scattering (TAOS) patterns retrieved from single aerosolized cells. These patterns are analyzed by performing autocorrelations and demonstrate the ability to retrieve cell size from the locations of the secondary maxima. Additional morphological information is contained in the autocorrelation functions and decay rate of the heights of the autocorrelation peaks. These techniques are demonstrated with C6 and Y79 cells, which are readily distinguishable. One key advantage of this methodology is that there is no requirement for antibody and fluorescent labeling molecules. | Two-Dimensional Angular Optical Scattering, Aerosolized Cells, Fluorescent Labeling |
“The MonRAt Telescope for Atmospheric Radiation” | Marcelo Leigui, C. J. Todero Peixoto, M. S. A. B. Leão, V.A. Ferra | Proceedings of the 32nd International Cosmic Ray Conference, ICRC 2011. 3. 239-242. 10.7529/ICRC2011/V03/1041 | The atmospheric radiation monitor MonRAt is a compact telescope being built in Brazil and designed to detect photons generated in the atmosphere by ultra-high energy cosmic ray showers. It is composed by a parabolic mirror focusing light onto a 64-pixel multianodic photomultiplier tube and ultraviolet-passing filters positioned in front of the photocathode. The data acquisition system consists of a set of pre-amplifiers and FPGA-based boards able to record trigger times and waveforms from each channel and send the data to a computer by USB ports. MonRAt is being designed to detect air fluorescence radiation under different atmospheric and geographic conditions and contribute to the study of the fluorescence radiation yield. Also planned are Cherenkov radiation measurements and monitoring of the atmosphere in the lidar mode. | Atmospheric radiation monitor, Cherenkov radiation, MonRAt, LIDAR |
“A Tangentially Viewing Fast Ion D-Alpha Diagnostic for NSTX” | A. Bortolon, W. W. Heidbrink, M. Podestà | Review of Scientific Instruments, Volume 81, 10D728, 25 October 2010 | A second fast ion D-alpha (FIDA) installation is planned at NSTX to complement the present perpendicular viewing FIDA diagnostics. Following the present diagnostic scheme, the new diagnostic will consist of two instruments: a spectroscopic diagnostic that measures fast ion spectra and profiles at 16 radial points with 5 –10 ms resolution and a system that uses a band pass filter and photomultiplier to measure changes in FIDA light with 50 kHz sampling rate. The new pair of FIDA instruments will view the heating beams tangentially. The viewing geometry minimizes spectral contamination by beam emission or edge sources of background emission. The improved velocity-space resolution will provide detailed information about neutral-beam current drive and about fast ion acceleration and transport by injected radio frequency waves and plasma instabilities. | NSTX, Fast Ion D-Alpha |
“First Measurements of Non-Interceptive Beam Profile Monitor Prototypes for Medium to High Current Hadron Accelerators” | J. M. Carmona, A. Ibarra, I. Podadera, Z. Abou-Haïdar, M. A. G. Alvarez, A. Bocci, B. Fernández, J. García López, M.C. Jiménez-Ramos | Proceedings of HB2010, Morschach, Switzerland, WEO1C04 | In the frame of the IFMIF-EVEDA accelerator project (a 125 mA, 9 MeV, 175 MHz (CW) deuteron accelerator) CIEMAT has designed and tested two types of non-interceptive optical monitors based on gas fluorescence. This beam diagnostic technique offers a non-invasive beam profile characterization for medium to high current hadron beams. Both monitors have been tested at CNA cyclotron using 9 MeV deuterons up to 40 uA and 18 MeV protons up to 10 uA. Profile measurements were carried out under high radiation background because the target and profilers were close to each other in the experimental setup. A Vertilon PhotoniQ IQSP482 with an SIB032 for the Hamamatsu H7260 32 channel multianode PMT was used for one of the fluorescence profile monitors (FPMs). In this paper, a brief description of FPMs together with the first beam measurements including systematic scans on beam current and pressure are presented. | IFMIF-EVEDA Accelerator, Deuterons, Hamamatsu H7260, CNA Cyclotron, 32 Channel PMT |
“The NSTX Fast-Ion D-alpha Diagnostic” | M. Podestá, W. W. Heidbrink, R. E. Bell, R. Feder | Review of Scientific Instruments, Volume 79, Number 10, October 2008 | A new diagnostic, aimed at energy-resolved measurements of the spatial and temporal dynamics of fast ions in NSTX plasmas, is described. It is based on active charge-exchange recombination spectroscopy. The fast-ion signal is inferred from light emitted in the wavelength range of the D-alpha line by fast ions recombining with an injected neutral beam. Two complementary systems are operational. The first system, based on a spectrometer coupled to a charge coupled device detector, has 16 channels with space, time, and energy resolution of 5 cm, 10 ms, and 10 keV, respectively. The second system monitors the energy-integrated fast-ion signal on time scales of ~20 µs at three different radii. Signals are measured by a multianode photomultiplier tube and acquired using a Vertilon PhotoniQ IQSP480. For both systems, each channel includes two paired views, intercepting and missing the neutral beam for a direct subtraction of the background signal not associated with fast ions. Examples of signals from the 2008 NSTX run are presented. | NSTX Plasma, Charge-Exchange Recombination Spectroscopy, Fast Ions |
“Classification and Selective Collection of Individual Aerosol Particles Using Laser-Induced Fluorescence” | Vasanthi Sivaprakasam, Timothy Pletcher, John E. Tucker, Alan L. Huston, Joseph McGinn, David Keller, and Jay D. Eversole | Applied Optics, Volume 48, Issue 4, pp. B126-B136 | Described is the development and performance evaluation of a system for optical interrogation, subsequent selection, and collection of individual aerosol particles entrained in an inlet air stream. Elastic scatter and laser-induced fluorescence obtained from single particles on-the-fly provide compositional information for classification criteria. Individual particles could then be selectively electrically charged and captured to a conductive substrate with an electric potential. The optical subsystem also includes a novel two-beam velocimeter to provide accurate downstream timing. Good overall quantitative performance values are reported for particles in the size range of 1-8 microm at mean rates up to 4 kHz. | Aerosol Particle Sorting, Elastic Scatter, Laser-Induced Fluorescence |
“Linear and Non-Linear Spectroscopy of Microparticles: Basic Principles, New Techniques and Promising Applications” | Richard K. Chang and Yong-Le Pan | Faraday Discussions, 2008, 137, 9-36 | The basic principles of whispering gallery modes (WGMs) and their relationship with electromagnetic theory are presented. To simplify the mathematics, we only discuss an example from a 2-d case of light illumination perpendicular to the fiber axis. This 2-d example has relevance to semiconductor circular disk lasers, nonlinear optics in torroids, fibers and spheres at the tip of a fiber. The internal and near-field distribution of a WGM are graphically plotted to give the reader a chance to get a physical understanding of the spatial distribution as well as spectral distribution of WGMs. Several new techniques that enable the measurements of: (1) nanometer changes in the cladding diameter over a centimeter length of fiber; (2) some aspects of the morphology of micro-particles by elastic scattering; and (3) biochemical reactions at the interface of liquid media with a sphere at the end of a fiber. A few interesting nonlinear optical experimental results pertaining to stimulated Raman scattering (SRS) are touched upon. We present some preliminary results for promising applications in the area of bioaerosols. These include ambient aerosol characterization and identification with elastic scattering, fluorescence spectroscopy, and other optical and/or biochemical identifiers. | Whispering Gallery Modes (WGMs), Stimulated Raman Scattering (SRS), Elastic Scattering, Fluorescence Spectroscopy |
“Project Mecanico para um Sistema PET Didactico” | Tiago Manuel Cabral de Alves Dias | Mestrado em Engenharia Fisica, Departamento de Fisica, 2010 | O projecto miniPET, “A PET System for Didatic Purposes”, desenvolvido no CFNUL – Centro de Física Nuclear da Universidade de Lisboa, tem por objectivo o desenho, construção e teste de um pequeno sistema de PET, constituído por 2 matrizes de 16 cristais de cintilação e 2 fotomultiplicadores de 16 canais. O protótipo idealizado deverá ilustrar os princípios de funcionamento de um PET comercial, visando contribuir, de uma forma didáctica, para a formação de alunos universitários e profissionais da área da medicina nuclear. O objectivo central deste trabalho é o desenho, construção e testes da mecânica do sistema PET Didáctico. Procedeu-se a diversos estudos que consistiram no desenvolvimento de propostas para a arquitectura do miniPET. Desenharam-se diversas geometrias distintas como soluções a implementar na estrutura de suporte mecânico do sistema miniPET, recorrendo ao software de CAD SolidWorks. Os modelos propostos tinham como finalidade encontrar soluções que suportem os módulos detectores e se adequem a uma geometria que possibilite a realização de testes de coincidências de fotões de 511KeV, bem como possam recriar um sistema PET clínico e os princípios físicos em que ele se baseia. Construíram-se e testaram-se diversas componentes essenciais ao projecto. O objectivo deste trabalho foi atingido, sendo que o modelo final proposto é um protótipo versátil, robusto, reprodutível e de fácil implementação, que inclui todos os requisitos a que o projecto se propôs. | PET, Photomultiplier Tube |
“Using Single Particle Fluorescence to Detect Bioaerosols” | Yong-Le Pan, Richard K. Chang, Steven C. Hill, Ronald G. Pinnick | Optics and Photonics News, September 2008 | Using single-particle fluorescence spectroscopy, scientists are conducting widespread, real-time monitoring of bioaerosols that will deepen their understanding of the effects of airborne particles on human health and climate change. | Single-Particle Fluorescence Spectroscopy, Bioaerosols |
“Real-Time Measurement of Dual-Wavelength Laser-Induced Fluorescence Spectra of Individual Aerosol Particles” | Hermes C. Huang, Yong-Le Pan, Steven C. Hill, Ronald G. Pinnick, Richard K. Chang, | Optics Express 16528, Volume 16, Number 21, October 13, 2008 | We report the development of an in-situ aerosol detection system capable of rapidly measuring dual-wavelength laser-induced fluorescence spectra of single particles on the fly using a single spectrometer and a single 32-anode photomultiplier array. We demonstrate the capability of this system with both reference samples and outdoor air. We present spectra from separate excitation wavelengths from the same particle that demonstrate improved discrimination capability compared with only using one excitation wavelength. | Dual-Wavelength Laser-Induced Fluorescence, 32-Anode Photomultiplier Array, Aerosol Detection |
“Multi-anode PMT Makes Possible the Detection, Discrimination, Enrichment, and Deposition of Bioaerosols On-the-Fly” | Yong-Le Pan, Richard K. Chang | Hamamatsu Corporation Applications | An approach based on the analysis of UV laser-induced fluorescence spectra (UV-LIF), has resulted in instruments that can continually and rapidly discriminate bio-threat-like aerosols from many ambient aerosols. However, this approach struggles with specific identification and produces high false alarm rates, especially in instruments that rely on only two or three fluorescence bands. To overcome these limitations, a combined method has been devised, in which the dispersed spectroscopy of the UV-LIF signal is used as a first-stage discriminator to prescreen the background aerosol particles and rapidly get rid of interfering aerosols, while specific biochemical technology is used to identify suspect aerosols with high accuracy for bioaerosol detection and characterization. | UV Laser-Induced Fluorescence Spectra (UV-LIF), Bioaerosol Fluorescence Detection |
“Selective Deflection and Localization of Flowing Aerosols onto a Substrate” | Matt Frain, David P. Schmidt, Yong-Le Pan, Richard K. Chang | Aerosol Science and Technology, 40:218–225, 2006 | Pulsed airflow cued by the fluorescence spectrum of a particular aerosol can be used to distinguish and deflect particles of biological origin out of an aerosol stream, permitting concentration of these particles for subsequent analysis. However, these high velocity pulses of air have an inherent tendency to scatter particles, confounding efforts to concentrate these deflected particles for analysis. The ability to concentrate large numbers of biological particles into a small area on a collection substrate is particularly important for more species-specific techniques such as Raman and FTIR (Fourier Transform Infra-Red) spectroscopy, which require long integration times due to their weak signal strength. Here, a simple method is developed for deflecting and localizing particles after classification by a pulsed airflow. The concept is both modeled and experimentally tested. A specially designed funnel is used to localize the scattered particles onto an area of substrate as small as 1 mm in diameter. Computational fluid dynamics simulations were performed to investigate the interaction of the pulsed airflow with the deflected particles and the localizing funnel, in order to gain insight into design parameters and operating conditions that affect the efficiency of this technique. The results show that the combination of pulsed airflow with a localizing funnel effectively deflects and localizes the concentrated bioaerosol onto a small area of substrate or an opening of a microfluidic cell. | Computational Fluid Dynamics, Microfluidic Cell, Bioaerosol Fluorescence |
“Development of a Multi-Angle Light Scattering Spectrometer for Aircraft Use” | William Dick, Keung Woo, Mihai Chiruta, Francisco Romay | MSP Corporation | A system that provides direct measurements of key properties needed for inversion of data from satellite-borne remote sensors & ground-based LIDAR systems for aerosol characterization over a large geographical area. Intersection of the aircraft flight path with the satellite path at the same point in time allows direct correlation of multiangle light scattering data and remote-sensing data. | LIDAR, Aerosols, Multiangle Light Scattering |
“290 and 340 nm UV LED Arrays for Fluorescence Detection from Single Airborne Particles” | Kristina Davitt, Yoon-Kyu Song, William R. Patterson III, Arto V. Nurmikko, Maria Gherasimova, Jung Han, Yong-Le Pan, Richard K. Chang | Optics Express 9548, Volume 13, Number 23, November 14, 2005 | A compact system is demonstrated, incorporating a 32-element linear array of ultraviolet (290 nm and 340 nm) light-emitting diodes (LEDs) and a multi-anode photomultiplier tube, to the in-flight fluorescence detection of aerosolized particles, here containing the biological molecules tryptophan and NADH. This system illustrates substantial advances in the growth and fabrication of new semiconductor UV light emitting devices and an evolution in packaging details for LEDs tailored to the bio-aerosol warning problem. Optical engineering strategies are employed which take advantage of the size and versatility of light-emitting diodes to develop a truly compact fluorescence detector. | Fluorescence Detection of Aerosolized Particles, Tryptophan, NADH, Hamamatsu H7260 PMT |
“Multiple-Anode PMT Behaves Like Many Detectors in One” | Yong-Le Pan and Richard K. Chang | Laser Focus World, Volume 37, Issue 5, May 2001 | Equivalent to having multiple photomultiplier tubes located in a single housing, the multiple-anode PMT can detect both the temporal and spatial distribution of signal intensity. The photomultiplier tube (PMT) is well-known as a single-photon-sensitive detector that measures the intensity as a function of time, well into the gigahertz range. The PMT cannot, however, measure the spatial distribution of the intensity. Nevertheless, the PMT is one of the detectors most frequently used in laboratory experiments and optical instrumentation. By contrast, a charge-coupled-device (CCD) detector - because of its numerous pixels - can measure the spatial variation of the intensity, but cannot measure frame changes at rates greater than 100 Hz. | Hamamatsu H7260 MAPMT, Single Photon Sensitivity |
"Multispectral Cytometry: The Next Generation" | J. Paul Robinson | Biophotonics International, October 2004, 36-40 | A multispectral flow cytometer is described in which a grating disperses signals from a fluorescence collector lens to a 32-channel Hamamatsu PMT. Detectors submit the data to the computational system, which determines hyperspectral curves for every particle and performs spectral unmixing. | Multispectral Flow Cytometer, Hamamatsu H7260 MAPMT, Fluorescence |
“Separating Hazardous Aerosols from Ambient Aerosols: Role of Fluorescence-Spectral Determination, Aerodynamic Deflector and Pulse Aerodynamic Localizer (PAL)” | Yong-le Pan, Patrick J. Cobler, Scott A. Rhodes, Justin Halverson, Richard K. Chang | Proceedings. of SPIE Vol. 5990 59900Y-1 | An aerosol deflection technique based on the single-shot UV-laser-induced fluorescence spectrum from a flowing particle is presented as a possible front-end bio-aerosol/hazardous-aerosol sensor/identifier. Cued by the fluorescence spectra, individual flowing bio-aerosol particles (1-10 um in diameter) have been successfully deflected from a stream of ambient aerosols. The electronics needed to compare the fluorescence spectrum of a particular particle with that of a pre-determined fluorescence spectrum are presented in some detail. The deflected particles, with and without going through a funnel for pulse aerodynamic localization (PAL), were collected onto a substrate for further analyses. To demonstrate how hazardous materials can be deflected, TbCl3·6H2O (a stimulant material for some chemical forms of Uranium Oxide) aerosol particles (2 um in diameter) mixed with Arizona road dust was separated and deflected with our system. | UV-Laser-Induced Fluorescence, Bioaerosols, Aerosol Deflection |
"Spectroscopic Sorting of Aerosols by a Compact Sensor Employing UV LEDs” | Kristina Davitt, Yoon-Kyu Song, William R. Patterson III, Arto V. Nurmikko, Yong-Le Pan, Richard K. Chang, Jung Han, Maria Gherasimova, Patrick J. Cobler, Paul D. Butler, Vincent Palermo | Aerosol Science and Technology, 40:1047–1051, 2006 | A compact sensor for physically sorting bioaerosols based on fluorescence spectra from single particles excited using arrays of ultraviolet light emitting diodes (UV LEDs) is presented. The optical system integrates electronics for real-time processing of spectral data and a miniaturized aerodynamic deflector for particle separation. Fluorescent polystyrene latex spheres are used to demonstrate fluorescence collection on-the-fly, operation of a real-time spectral algorithm, and physical separation of individual particles. This sensor illustrates the utility of recently developed UV LEDs, in conjunction with novel optical design and custom electronics, to shrink the size of aerosol fluorescence detection systems. | Fluorescence Detection, Sorting of Aerosolized Particles, Hamamatsu H7260 PMT |
“High-speed, High-sensitivity Aerosol Fluorescence Spectrum Detection Using a 32-anode Photomultiplier Tube Detector” | Yong-le Pan, Patrick Cobler, Scott Rhodes, Alexander Potter, Tim Chou, Stephen Holler, Richard K. Chang, Ronald G. Pinnick, Jean-Pierre Wolf | Review of Scientific Instruments, Volume 72, Number 3, March 2001 | A 32-anode photomultiplier tube (PMT) is employed in a fluorescence detection system to demonstrate its ability to record broad fluorescence spectra at frame rates in excess of 1400 Hz, which is 56 times faster than the frame rate of an intensified charge coupled device detector. The multi-anode PMT has single-photon detectable sensitivity. A new data acquisition and processing system for the multi-anode PMT, together with the system-controlling software, has been developed. The performance characteristics of the fluorescence detection system, including the data rate capability, dynamic range, signal-to-noise ratio, and crosstalk among the different anodes, are reported. The 32-anode PMT and acquisition system are suitable for a real-time, field-portable, multichannel optical analyzer. | Fluorescence Detection, Single Photon Sensitivity, Hamamatsu H7260 PMT |