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Jan 29, 2022, 8:35:05 AM
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Photodetectors, Homeland security, Astrophysics

Session chair: Mihara , Satoshi (High Energy Accelerator Research Organization (KEK), Tsukuba, Japan); Shimazoe , Kenji (University of Tokyo, Department of Nuclear Engineering and Management, Bunkyo, Japan)
Shortcut: N-11
Date: Wednesday, 20 October, 2021, 7:00 AM - 8:45 AM
Room: NSS - 3
Session type: NSS Session


Click on an contribution to preview the abstract content.

7:00 AM N-11-01

Verification of the applicability of water Cherenkov detector to active neutron method and development of a prototype detector (#127)

K. Tanabe1, 2, M. Komeda3, Y. Toh3, Y. Kitamura4, T. Misawa4, H. Sagara2

1 National Research Institute of Police Science, Kashiwa, Japan
2 Tokyo Institute of Technology, Meguro, Japan
3 Japan Atomic Energy Agency, Tokai, Japan
4 Kyoto University, Kyoto, Japan


In the fields of nuclear security, a compact and low-cost non-destructive assay system to detect hidden nuclear material is required. Because the conventional active neutron method adopts an accelerator neutron source and 3He detectors, existing instruments are expensive and poorly portable. To solve this problem, we have developed an innovative nuclear material detection method using a 252Cf source, which is called the rotation method. In this study, we developed a water Cherenkov detector as a novel low-cost neutron detector to replace 3He detectors. The applicability of the water Cherenkov detector to the rotation method was validated using simulation. Subsequently, a prototype detector was subjected to a demonstration experiment, combined with the rotation device. As a result, the fission neutrons from nuclear material were measured by using pulse height discrimination. Our study shows a potential of the water Cherenkov detector as a neutron detector for the rotation method.


This work was supported by JSPS KAKENHI Grant Numbers JP20K15213. The experiments were carried out at the Institute for Integrated Radiation and Nuclear Science, Kyoto University (KURNS).

Keywords: Cherenkov, NDA, Neutron detector, Nuclear non-proliferation, Nuclear security
7:10 AM N-11-02

Single Event Tolerance of X-ray SOI Pixel Sensors (#171)

K. Hagino1, M. Hayashida1, T. Kohmura1, T. Doi1, S. Tsunomachi1, A. Fujimori1, K. Maekawa1, M. Kitajima1, T. G. Tsuru2, H. Uchida2, K. Kayama2, R. Kodama2, K. Mori3, A. Takeda3, Y. Nishioka3, M. Yukumoto3, K. Mieda3, S. Yonemura3, T. Ishida3, T. Tanaka4, Y. Arai5, I. Kurachi6, H. Kitamura7, S. Kawahito8, K. Yasutomi8, M. Ueno9, M. Ozaki9, H. Nakajima10

1 Tokyo University of Science, Noda, Japan
2 Kyoto University, Kyoto, Japan
3 University of Miyazaki, Miyazaki, Japan
4 Konan University, Kobe, Japan
5 KEK, Tsukuba, Japan
6 D & S Inc., Tokyo, Japan
7 QST, Chiba, Japan
8 Shizuoka University, Hamamatsu, Japan
9 JAXA, Sagamihara, Japan
10 Kanto Gakuin University, Yokohama, Japan


We have been developing the X-ray SOI pixel sensor named “XRPIX” for the future X-ray astronomical satellite, FORCE. XRPIX is a monolithic active pixel sensor composed of a high-resistivity Si sensor, thin SiO2 insulator, and CMOS pixel circuits by utilizing the silicon-on-insulator (SOI) technology. Since XRPIX is capable of event-driven readout, it can achieve a high timing resolution better than ∼10 μs, which enables an extremely low background observation by adopting the anti-coincidence technique. The tolerance to single event upset (SEU) should be considered in the development of the CMOS integrated circuits for space use. Although the SOI-CMOS used in XRPIX is expected to be less sensitive to the SEU, it is necessary to measure the SEU cross-section, and quantitatively evaluate the SEU tolerance of XRPIX. In this work, we measure the cross-section of SEU of the shift register on XRPIX by irradiating heavy ion beams with linear energy transfer (LET) ranging from 0.0220 MeV/(mg/cm2) to 66.5 MeV/(mg/cm2). From the SEU cross-section curve, the saturation cross-section and threshold LET are successfully obtained to be 7.9−3.9+1.6 MeV/(mg/cm2 ) and 3.4−0.8+2.5 × 10−10 cm2/bit, respectively. Using these values, the SEU rate in orbit is estimated to be ∼0.03 event/year primarily due to the secondary particles induced by cosmic-ray protons. This SEU rate of the shift register on XRPIX is negligible in the FORCE orbit.

Keywords: single event effect, silicon-on-insulator technology, SOI pixel sensor, X-ray astronomy
7:20 AM N-11-03

In-orbit radiation damage characterization of SiPMs in GRID-02 CubeSat detector (#1289)

X. Zheng1, J. Wen1, H. Gao1, M. Zeng1

1 Tsinghua University, Department of Engineering Physics, Beijing, China

On behalf of the GRID collaboration.


Silicon photomultiplier (SiPM) has recently been used in several space-borne missions for scintillator readout, thanks to its solid state, compact size, low operating voltage and insensitivity to magnetic fields. However, a known issue of operating SiPM in space environment is the radiation damage and thus the performance degradation. In-orbit quantitative study of these effects is still very limited. In this work we present in-orbit SiPM characterization results obtained by the second detector of Gamma-Ray Integrated Detectors (GRID-02), which was launched on Nov. 6, 2020. An increase in dark current of ~100 μA/year per SiPM chip (model SensL MicroFJ-60035-TSV) at 28.5 V and 5°C is observed, and consequently the overall noise level (sigma) of GRID-02 detector increases ~7.5 keV/year. This increase is estimated to be ~50 μA/year per SiPM chip at -20°C, which indicates good effect of using a cooling system.
AcknowledgmentM. Zeng acknowledges funding support from the Tsinghua University Initiative Scientific Research Program.
Keywords: CubeSat, Dark current, Radiation damage, SiPM
7:30 AM N-11-04

The CYGNO experiment (#979)

D. Pinci1, G. Dho2

1 INFN - Istituto Nazionale di Fisica Nucleare, Sezione di Roma, Roma, Italy
2 Gran Sasso Science Institute, L'Aquila, Italy

On behalf CYGNO-Collaboration


The CYGNO collaboration is working at the development of gaseous TPC, operated at atmospheric pressure with an He/CF4 based mixture optically readout as a promising technique for the search of Weakly Interactive Massive Particles as possible constituent of Dark Matter. The use of a low mass nucleus together with the high sensitivity provided by the optical readout  approach allow to explore with a very good efficiency the 1-10 GeV mass region. Morevoer, the complete set of information (energy released direction, position and length of the recoil track) makes it possible to develop a rejection of the photon induced background larger than 99% even below 10 keV. The measured detector performance will be presented together with a discussion about the prospective for Dark Matter search and Solar Neutrino Physics. The collaboration is now working at the construction of 1 m3 demonstrator to test the scalability of the performance of this technics at the scale of a large experiment. Expected sensitivities and performance will be analised.

Keywords: TPC, Optical Readout, Dark Matter Search
7:40 AM N-11-05

Time and Energy Resolution of Organic Glass Scintillators for Radionuclide Monitoring (#1099)

L. M. Clark1, N. Giha1, S. D. Clarke1, S. A. Pozzi1

1 University of Michigan / Nuclear Engineering, Ann Arbor, Michigan, United States of America


The Comprehensive Nuclear-Test-Ban Treaty of 1996 seeks to prohibit nuclear explosions around the world and utilizes the International Monitoring System for treaty verification. One area of detection in the IMS involves radionuclide monitoring of radioxenon isotopes that are emitted into the atmosphere during a nuclear test. Current monitoring systems employ an ensemble of plastic and inorganic scintillators to detect the coincident beta-gamma emission characteristic of several radioxenon isotopes. Organic scintillators are common detectors used in many nuclear nonproliferation applications due to their high efficiency and capabilities to detect and discriminate between neutrons and gamma rays. Chemists at Sandia National Laboratories have recently developed an organic glass scintillating material that exhibits pulse shape discrimination capabilities and higher light output than other leading scintillation materials, making it a viable choice for replacing plastic scintillators in radioxenon monitoring systems. To investigate the organic glass performance for this application, characterization and optimization of the material are necessary. In this work, we present new experimental results of organic glass scintillators of various thicknesses and reflector wrappings. We evaluate the pulse shape discrimination (PSD), efficiency, and time and energy resolution of these detectors.

AcknowledgmentWe would like to thank Sandia National Laboratories for provided the scintillation material used in this work. This work was supported in-part by the Consortium for Monitoring, Technology, and Verification under Department of Energy National Nuclear Security Administration award number DE-NA0003920.
Keywords: Organic glass scintillator, timing resolution, energy resolution, radionuclide monitoring
7:50 AM N-11-06

Small-scale neutron resonance transmission analysis (NRTA): epithermal neutron beam generation using a linAC versus a fusion source (#366)

P. L. Levine1, A. Danagoulian1

1 Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, Cambridge, Massachusetts, United States of America


Neutron resonance transmission analysis (NRTA) uses resonant absorption unique to individual nuclei to identify the isotopic composition of a target object. NRTA is useful for applications such as materials analysis, fuel enrichment analysis, and warhead verification in arms control treaties. However, NRTA remains widely inaccessible because it typically uses high-intensity neutron beams at large, expensive facilities.

This work explores two alternative methods of epithermal (1-10 eV) neutron beam generation that aim to make NRTA smaller, cheaper, and mobile: generation by fusion source and by electron linear accelerator. Fusion generators are interesting for study because they produce neutrons using a compact setup. However, those neutrons have high energy, so they require more shielding and have a lower moderation efficiency to the epithermal range. Electron linear accelerators are worthy of study because they have been used to efficiently produce high neutron fluxes in a well-known system, but conversion to neutrons involves bremsstrahlung radiation, i.e. x-rays that need significant shielding.

Beam generation methods are simulated using Grasshopper, a simulation engine using Geant4. Grasshopper generates simple Monte Carlo simulations of particle interactions and produces a 3D visualization of setup geometry and interactions. These simulations provide preliminary knowledge about optimal materials, thicknesses, and geometries to inform the feasibility of the system and possible direction for experiments. This work is a trade study between linear accelerators and fusion sources as methods of epithermal neutron generation for NRTA. Preliminary results indicate that linear accelerators are capable of generating comparable total neutron fluxes to DT generators. This talk will discuss the results of the simulations and the conclusions.

Keywords: neutron resonance transmission analysis, epithermal neutron beam, warhead verification, electron linear accelerator, fusion generator
8:00 AM N-11-07

Improved Data Analysis Techniques for the Development of a Portable Time Projection Chamber (#1182)

W. L. Koch1, 2, A. Danagoulian2, R. Lanza3, P. Fisher4, B. Horn5, E. Gonzalez1, V. Gasparri1

1 United States Military Academy, Physics and Nuclear Engineering, West Point, New York, United States of America
2 Massachusetts Institute of Technology, Nuclear Science and Engineering, Cambridge, Massachusetts, United States of America
3 Massachusetts Institute of Technology, Nuclear Science and Engineering, Cambridge, Massachusetts, United States of America
4 Massachusetts Institute of Technology, Physics, Cambridge, Massachusetts, United States of America
5 Massachusetts Institute of Technology, Computer Science & Artificial Intelligence Lab, Cambridge, Massachusetts, United States of America


Locating and characterizing a source of radiation are necessities in a variety of scenarios, including nuclear accidents, acts of terrorism, International Atomic Energy Association (IAEA) safeguards inspections, and military searches for illicit nuclear weapons programs. Over the history of radiation detection development, neutron detectors capable of locating a source of radiation rely on heavily moderating the signal in devices similar to coded apertures and time encoded detectors or on multiple scattering similar to neutron scatter cameras. A portable and mobile Time Projection Chamber (TPC) has a low gamma sensitivity and capitalizes on the directional nature of the signal to offset the nearly omnidirectional, cosmic-generated, fast neutron background.  This research highlights improved data analysis to improve the three dimensional reconstruction of an alpha recoil track to improve the spatial and time resolution.  The combination of improved treatment of data combined with portability upgrades allow the possibility of a one-person portable configuration where multiple detectors carried by multiple people are building a probabilistic model of source locations. This equipment will enhance the capabilities of first responders in a variety of scenarios involving searches for radioactive material.

Keywords: Fast neutron detection, Nuclear security, Data analysis
8:10 AM N-11-08

X-ray Backscatter Security Inspection with Enhanced Depth of Effective Detection and Material Discrimination (#898)

A. Arodzero1, 2, V. Alreja3, S. Boucher1, P. Burstein4, P. Kulinich1, R. C. Lanza2, V. Palermo5, M. Tran3

1 RadiaBeam Technologies, LLC, Santa Monica, California, United States of America
2 Massachusetts Institute of Technology, Nuclear Science and Engineering, Cambridge, Massachusetts, United States of America
3 VJ Technologies, Inc., Bohemia, New York, United States of America
4 Skiametrics, LLC, Winchester, Massachusetts, United States of America
5 Vertilon Corp., Westford, Massachusetts, United States of America


X-ray imaging techniques based on Compton backscatter allow inspection and screening of a variety of vehicles, cargo containers, luggage, suspicious packages, aircraft and spacecraft components, as well as building walls and floors. Backscatter imaging systems are in wide use by government agencies, border authorities, law enforcement personnel, military organizations, and security services in many countries.
In contrast to commonly used transmission inspection systems, backscatter imaging involves positioning both radiation source and detectors on the same side of a target object. Such systems are exceptionally useful in situations where access to the inspected object is limited to a single side, making X-ray transmission system impractical.

Conventional backscatter inspection systems have a significant limitation in their ability to penetrate even moderately dense objects. Moreover, the signal is dominated by the first interrogated layer, e.g., the metal wall of a container or vehicle, or the front layer of wall. To overcome this fundamental limitation, we develop an advanced inspection technique, DeepBx, which uses energy- and current- modulated X-ray pulses, fast, time-resolving X-ray detectors, and an algorithm of image “peeling” processing.

We will present the results of testing a lab prototype of the DeepBx Imager: detection of prohibited substances hidden in phantoms of various objects and structures. These results will be presented in comparison with conventional backscatter imaging approaches.

Keywords: Homeland Security, X-ray backscatter imaging, Contraband detection, Explosive detection, Non-destractive inspection
8:20 AM N-11-09

Investigation of Novel Selective Emitter Structure for Ultraviolet Sensitive SiPM (#1079)

Y. Tao1, A. Erickson1

1 Georgia Institute of Technology, Nuclear and Radiological Engineering and Medical Physics Programs, G. W. Woodruff School of Mechanical Engineering, Atlanta, Georgia, United States of America


To achieve high quantum efficiency and hence high photo-detection efficiency for ultraviolet sensitive silicon photomultipliers (SiPM), carrier recombination needs to be minimized to allow the photo-generated primary carrier to traverse to the high-field region to trigger avalanche event. However, the homogeneous emitter structure in conventional SiPM causes a limited device performance, because a low doping level is required for low recombination in the active area, meanwhile a high doping level is necessary to reduce the metal-induced recombination as well as the contact resistance. Therefore, in this paper, we investigate a selective emitter (p+/p++) structure to replace the conventional homogeneous emitter (p+) to mitigate this trade-off to develop high-performance ultraviolet sensitive SiPM. Implementing the selective emitter structure by reducing the doping level in the active area (p+) from 2 × 1019 to 5 × 1018 cm-3, the emitter saturation current density J0e can improved from 48 to 14 fA/cm2. Meanwhile the metal-induced recombination is significantly reduced by increasing the doping level of heavily doped region beneath the front contact metal (p++) to 7 × 1019 cm-3. As a result, the internal quantum efficiency and photo-detection efficiency can be improved. In addition, the selective emitter structure yields lower contact resistance, which leads to faster discharge process. These demonstrate the potential of selective emitter structure. Further investigation is in process by employing selective emitter structure into SiPM prototype device.


This material is based upon work supported by the Department of Energy / National Nuclear Security Administration under Award Number(s) DE-NA0003921.

Keywords: SiPM, Selective Emitter, Recombination, Quantum Efficiency, Contact Resistance

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