This PDF file contains the front matter associated with SPIE Proceedings Volume 12696, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

A team of scientists from the Remote Sensing Laboratory at Joint Base Andrews, Maryland, has assembled a remotecontrolled robot to field a few sodium iodide scintillators of different sizes and shapes 18″ above ground for measurement of ground deposition of gamma-emitting particles after an explosion of a radiological dispersal device. This system uses a high-precision differential GPS device with submeter accuracy for radiation mapping. The system is most useful in characterizing large-area contamination and detecting gamma radioactivity in invisible, submicron particulate debris deposited on the ground at surface level or embedded in subsurface up to 3″ deep. The system was assembled as part of a larger effort to integrate advanced radiological detection devices into autonomous or remote-controlled robotic systems to eliminate or minimize the need for emergency responders to enter areas that pose significant health and safety risks to humans following a major radiological incident or accident. Research into autonomous algorithms is required to develop automated robotic systems for radiological survey and characterization activities in highly contaminated areas. The scope of this project also includes developing communications pathways and supporting infrastructure capabilities for different types of robotic technologies. The expected result is an advanced autonomous robotic system with integrated radiation detection electronics that allows emergency response personnel to view data remotely and in real time for radiological emergency response and consequence management purposes.

The Neutron Radiation Detection Instrument-1A (NeRDI-1A) is a neutron sensor on the International Space Station (ISS) as part of the Department of Defense Space Test Program (STP) mission STP-H9. NeRDI-1A uses the scintillator Tl₂LiYCl₆:Ce as well as three Domino microstructured semiconductor neutron detectors (MSNDs) with varying levels of moderation and an EJ-270 plastic scintillator. The primary objective of NeRDI-1A is to space qualify TLYC and MSND detectors by studying the effects of on-orbit radiation background on the performance of these detectors over the nominal one-year mission. NeRDI-1A was launched to the ISS on 15 March 2023 GMT aboard SpX-27.

We have developed high efficiency, variable-energy x-ray sources based on distributed coupling linacs. These linear accelerators have >2x beam-to-RF efficiency compared to conventional linacs. Separate feeds for cavities allow for their individual optimization for maximum output instead of feeding the RF power through the electron-beam pipe as is done conventionally. In addition, the framework for beam dynamics calculation accounts for beam loading in the cavities and iterates till a steady state solution is achieved. The linac cavities are machined into two symmetric blocks of copper that are diffusion-bonded together. The ports for RF feed, the flanges for the electron gun and the target are then brazed on. Special attention was paid to the mechanical design and assembly process to enable high yield production. Our linacs have an integrated buncher section where the first cavity has a separate feed. By controlling the amplitude and phase of the RF into this port, the beam energy and intensity can be varied. We have completed the design and are in various stages of building and high-power testing linacs for 2.5, 6 and 12 MeV for medical and for security and inspection purposes. We have also designed and are building the RF and electrical power sources including high power modulators and klystrons for supplying the RF and electrical power needed to run these linacs. The modulators are built using Marx-bank capacitor approach. The klystrons design follows a split-structure manufacturing technique, and their design fully accounts for beam loading with iteratively calculated steady state solution.

We have recently demonstrated significant improvements to the resolution and sensitivity of the NIF gamma imaging system by replacing the existing EJ262 plastic scintillator with the Ce-doped gadolinium garnet transparent ceramic scintillator GYGAG. Penumbral imaging of inelastic gammas emitted during inertial confinement fusion (ICF) experiments at NIF can be used to recover the time integrated spatial distribution of the remaining shell during the fusion burn, the technique is therefore a critical diagnostic for understanding the failure modes and quality of NIF implosions. In this work we discuss GEANT4 calculations of the relative sensitivities of GYGAG and EJ262 as well as rolled edge measurements made on NIF shot N221204 in December 2022, for the purpose of directly comparing the spatial resolution of each scintillator in-situ.

For decades, fast neutron radiography performed using pulse-counting detectors employed PMTs coupled to plastic scintillator pixel arrays. SiPM-based systems are now sought to replace fragile PMTs, but conventional, “analog” SiPMs suffer from intrinsic limitations which limit their achievable performance. Among these limitations, a complete analog readout and digitizer chain is required, a counterintuitive approach when considering that the single-photon avalanche diode (SPAD), the basic unit cell of SiPMs, is a Boolean detector providing digital detection at the sensor level. This paper outlines a new concept for neutron radiography instrumentation by using photon-to-digital converters (PDCs, aka digital SiPMs), a fully digital solution to sense the scintillation light.

Imaging stitching is a solution for radiography and computed tomography (CT) applications where the object is larger than the beam size. Imaging stitching algorithms require a robust noise filter that maintains the landmark features used in stitching. In lens-coupled neutron radiography and CT, a camera is placed away from the neutron beam. Even with shielding, the camera experiences a high radiation dose of mixed gammas and neutrons. The CCD silicon sensor, sensitive to both gammas and neutrons, introduces speckled noise, pixel oversaturation, and blooming effects. Conventional median filters prove inadequate with this type of noise and can result in blurred images. Manual filtering of CT sets is time-consuming and error-prone. An improved image filtering method designed for neutron CT data sets is therefore needed to improve imaging stitching algorithms. We have developed a method that utilizes statistical information in radiographs and variable-sized radii filtration to adequately remove noise while preserving resolution. Once noise has been identified, the algorithm tracks cluster size to inform local filter needs. Filtered radiographs are stitched using a semi-automatic algorithm. This approach works best for data containing features for joint corner detection. It does require specific user inputs, such as object size, features of interest, and alignment, to pinpoint the optimal joining location. Overall, our method represents a significant advancement in neutron CT image processing, offering improved results for imaging stitching and traditional CT applications. We describe the application of this combined filter and stitching algorithm on thermal and fast neutron CT data at OSURR.

Recent material advancements in plastic scintillators enable marked increases in material light yield, detection efficiency, pulse-shape discrimination, and array production rates. These advances may resolve significant capability gaps for lowcost, portable, and durable dual-particle imaging (DPI) systems for nuclear safety, security and safeguard purposes. Two such materials, both 21% bismuth-loaded plastics utilizing iridium complex fluorophores (Ir-Bi-Plastic) were experimentally evaluated for DPI purposes as a small, pixelated radiographic array and compared to similar arrays made from EJ-200 and EJ-256 (5 wt% Pb). Experimentation involved separate exposures to 370 kVp x-rays and 14.1 MeV neutrons when paired with a digital radiographic panel, and array performance was evaluated using ASTM methods for dSNRn determination. Additionally, the development of fast-curing plastic scintillator (FCPS) formulations is highly attractive because it facilitates the 3D-printing of complete pixelated plastic scintillator arrays for radiation detection and localization. Future advancements in this area will significantly reduce the time and costs associated with current array manufacturing techniques. Some early investigations of FCPS samples sensitized with 5 wt% Bi is discussed herein, with their gamma detection efficiencies and associated light yields compared to an equivalent sample of EJ-256. These early unoptimized samples provided similar but not superior performance to EJ-256, and this is an ongoing area of research at the Air Force Institute of Technology.

Pixelated arrays of the transparent ceramic (Gd,Lu)₂O₃:Eu (GLO) scintillator for x-ray imaging have been fabricated using direct ink write (DIW) additive manufacturing followed by sintering and ceramics processing steps. These arrays consist of ~400 μm diameter pixels that are 4 mm long and have a pitch of 500 μm. When mounted on an amorphous silicon xray imaging array, pixelated GLO arrays offer >10x increase in the light output compared to black-coated monolithic GLO plates, using a 150 keV Bremsstrahlung source.

The Daedalus sensor is the next version of the nanosecond time-gated, multi-frame hybridized CMOS (hCMOS) x-ray sensor, developed by Sandia National Laboratories (SNL). The Daedalus sensor leverages previous hCMOS features such as nanosecond gated frames while expanding features for increased record length, improved full well depth, and one-side abutment capability. The second version of the Daedalus sensor, the DV2, resolves an increased record length feature called interlacing in addition to the sensor’s ability to hold the integrated electrical charge from photocurrent for longer periods of time needed for full dynamic range during readout. The DV2 sensor characteristics, including background oscillations, skew, key sensor features for timing and high full well, and mapping of the internal temperature sensor are presented and discussed.

The harsh radiation environment of Lawrence Livermore’s National Ignition Facility (NIF) requires radiation tolerant scientific cameras for our wide array of diagnostics. Our current scientific cameras, SI-1000 CCD cameras developed by Spectral Instruments, have a multitude of problems on high neutron yield NIF experiments including upsets that cause complete loss of experimental data as well as significant damage to the sensors. Our goal was to develop a CMOS-based scientific camera platform that would be significantly more radiation tolerant than the current suite of CCD cameras used in NIF diagnostics. That is, the camera electronics would operate through high neutron yield experiments and that the sensors would sustain far less damage thus increasing their life expectancy. That camera platform, the 1600S CMOS cameras, developed by Spectral Instruments (SI) was designed to accept a variety of different sensors up to 60 mm x 60 mm depending on the specific application. In this paper we will discuss the development, general performance, and radiation performance of the CIS-54, a dump and read 1600S CMOS camera with a Stanford Research Institute (SRI) developed 4k x 4k sensor.

We constructed x-ray tracking detectors by coupling a perovskite X-ray scintillating film to several commercially available cameras. Perovskite x-ray scintillators are an attractive alternative to traditional scintillators due to their compelling combination of high light output, impressive resolution, low afterglow, and ultrafast speed. We coupled the perovskite film to a high dynamic range event-based sensor as well as to two regular CMOS monochrome cameras. We compare results of the perovskite-based x-ray tracker using the event-based sensor with the regular imaging cameras. Furthermore, as an example application, we will show the use of the x-ray tracker as a beam finder for an x-ray beamline experiment.

Neutron Depth Profiling (NDP) is an analytical neutron technique that continues to grow in popularity for the quantification of Li ions in lithium-ion battery (LIB) materials. Most investigations occur at high flux neutron sources, i.e. cold or thermal neutron beam facilities, offered by high-power (10-20 MW) research reactors and employing multiple NDP energy and concentration standards. This work aims to develop a feasible method using NDP facilities with less intense neutron flux at lower power research reactors to quantitatively determine the Li concentration in LIB materials, while also applying a “thick” energy and concentration standard. Here, we describe a methodology for processing and calibrating NDP data collected using a multi-detector (i.e., 7-detector setup), which is essential to increase the detection efficiency. The Li concentration of a Li₆PS₅Cl_0.5Br_0.5 solid-state electrolyte was determined to be 2.2×10²² Li atoms cm⁻³. This value deviated by less than 3% of the expected Li atom concentration using a “thick” LiF single crystal wafer as a concentration standard. The method described in this work can be applied to other low-power reactors and other NDP-sensitive isotopes to further increase the application and availability of user-based NDP facilities.

The performance of the Cherenkov threshold detectors (XCET) used in the secondary beam areas (SBA) at CERN is limited by their built-in optics. This study showcases an improved design using compound parabolic concentrators (CPCs) to reduce size and cost of the optics while optimizing the light collection efficiency. The detector was simulated with Geant4 over its full experimental range in terms of pressure, beam momentum, and particle type. The efficiency of the current design was found to be limited by the geometry of the parabolic mirror. The optimized CPC designs resulted in a size reduction of up to 54% and improved photon collection up to 67% compared to the original design when using CO2 as radiator gas and 276% when using R-218. These results highlight the advantages of using CPC and Monte Carlo simulations in the development of Cherenkov threshold detectors and may be useful for further improvements in the next generation of the XCET.

We are presenting a new readout circuit developed for the PbWO4 scintillation detectors for the Electron Ion Collider (EIC) EEEMCAL. The design is centered around a 4 x 4 matrix of fast silicon photomultiplier (SiPM) sensors which are directly coupled to a preamplification stage, and which cover an area of 20 mm x 20 mm. The architecture allows for a small footprint where the signal extraction, summation and amplification are performed in addition to the SiPM bias supply and a gain and offset adjustment circuit with settings saved in local memory. The SiPM overvoltage is temperature compensated to provide additional gain stability to the unit. Adjustments to gain and offset are done remotely through a communication port. The design was optimized for spectral resolution, fast response and large dynamic range with a small footprint and low energy consumption/heat dissipation that does not require active cooling for stable operation. These features are very important for future implementation at EIC where thousands of modules will be assembled in a compact manner for the Electron Endcap Electromagnetic Calorimeter. In addition, this readout development presents many features and performance capabilities that make it an excellent choice for scintillation detectors in other research and industrial applications. The signal output can be adjusted for negative amplitude with 0V baseline like that of a PMT to mate to existing pulse acquisition infrastructure. A detector prototype was constructed with a 3x3 array of 20 mm x 20 mm x 200 mm PbWO4 crystals coupled to individual sensor arrays and readouts. The detector was tested at the Thomas Jefferson National Accelerator Facility with 5GeV positrons. We will present the results of these detector characterization measurements.

The Nevada National Security Site (NNSS) provides a comprehensive bicoastal radiological and nuclear emergency response to United States Department of Energy/National Nuclear Security Administration. A major part of the support is to provide systematic radiological search for lost or stolen sources, Radiological search is a core competency of the NNSS with its origin dating back to nuclear weapons test era. Search operations from multiple platforms is the common thread among the various NNSS assets, which include Aerial Measuring System (AMS), Maritime Support Team (MST), National Capitol Response (NCR), National Search Team (NST) and Radiological Assistance Program (RAP). Information collected and analyzed during search operations add to the actionable intelligence for the law enforcement agencies and provide valuable guidance for the tactical resolution of a nuclear or radiological crisis. Search is an intelligence and situational awareness driven operation and most often called upon during a radiological emergency, however it can be brought into play to thwart a potential threat by providing monitoring and surveillance support. The Office of Nuclear Incident Response (NA-84) serves as the technical leader in responding to and resolving nuclear and radiological threats worldwide and integrates its efforts with other NNSA stakeholders (e.g., NNSA office of Defense Nuclear Non-proliferation NA-22). The response includes expertise in the areas of radiological search, render safe, and consequence management. This article will discuss the methodologies, tools, procedures, and techniques to extract maximum radiological characterization information (isotopic composition, activities for individual isotopes, threat assessment etc.) from field monitoring or Search operation data.

New technical approaches are needed to verify compliance with existing and proposed nuclear treaties. Special nuclear material (SNM) is a major focus because it is a necessary component of a nuclear weapon. Recently developed scintillator detectors have application in the development of new radiation detectors suitable for these applications. We discuss new approaches for fast neutron and gamma ray detection, spectroscopy, and imaging using these new instruments. Results from measurements with kilogram-quantities of SNM, including plutonium and highly enriched uranium, demonstrate the use of these instruments in nuclear treaty verification.

Electronic grade diamond such as single crystal (SC) chemical vapor deposition (CVD) diamond has excellent optoelectronic properties, which enables it to be used as a detector material for high energy detector applications. However, SC CVD diamond suffers from loss of signal contrast and performance over a period of continuous use due to polarization of the detector. When a SC CVD diamond is continuously exposed to radiation, trapped charge carriers build up at defect sites, resulting in the creation of a secondary electric field opposite to the bias field. The emergence of the secondary electric field causes charge collection efficiency loss and reduces the overall performance of the detector. In this work, the effect of polarization on the direct current (DC) neutron response of a 500 μm SC CVD diamond detector was investigated by irradiating the detector with 14.1 MeV neutrons produced from a deuterium-tritium neutron generator. Depolarization techniques were employed to de-trap charge carriers and decrease the strength of the secondary electric field. This was primarily through reverse biasing the applied field yet included scenarios with and without short-lived neutron irradiation. The results indicated that both without and with neutron irradiation techniques improved the stability of the detector response. The latter showed a superior stability at higher bias fields.

We investigated melting and crystallization processes of Cd_0.50Mn_0.50Te. Using differential thermal analysis (DTA) we studied the solid-liquid equilibrium temperature range, the temperature dependence of the volume fraction of the solid phase in the melt, and crystallization peculiarities. We observed that changing a dwell temperature from 1346 to 1354 K results in an increase of the crystallization temperature of the Cd_0.50Mn_0.50Te melt. Since the melt is in a semiliquid state, its crystallization occurs over a solid-phase domain. It was found that a slightly overheated Cd_0.50Mn_0.50Te melt (up to 10 K) crystallizes more slowly than more overheated melts, and that the Cd_0.50Mn_0.50Te solid solutions are in a semi-liquid state in the temperature range of 1338-1354 K.

Methods were developed for the synthesis and growth of the inorganic perovskite CsPbBr₃, which can be used for detection of optical, x-ray, and γ-radiation. The growth of single crystals of these compounds was carried out by the Bridgman method in quartz ampoules using zone-refined starting materials. The electro-physical properties of the lead cesium tribromide CsPbBr₃ were studied. Two types of structures with a Cr/CsPbBr₃/Ni rectifying barrier and Ni/CsPbBr₃/Ni ohmic contacts were created. The resistivity of the semiconductor material (ρ≈7×10⁹ Ohm•cm) and the activation energy of the dark conductivity (▵E≈0.8 eV) were determined. From the measurements of the optical transmission spectra, the energy gap of CsPbBr₃ at 300 K was found to be Е_g = 2.27 eV. The temperature dependence of the forbidden gap (E_g(T) = 2.4 - 4*10^-4 T, eV) was also determined. A significant increase in photosensitivity for the Cr/CsPbBr₃/Ni structure was observed at elevated temperatures. The Cr/CsPbBr₃/Ni structures were shown to be sensitive to γ radiation. The FWHM of the energy resolution for an ²⁴¹Am source was measured to be 15.8 keV.

The electrical characteristics of CdTe-based surface barrier structures, which can be used as spectroscopic X/γ-ray detectors, have been investigated. The metal-semiconductor structures were obtained by thermal (resistive) vacuum deposition of various metals onto detector-grade CdTe crystals. Metals with different work functions, such as Al, In, Ni, Ti, Cr, and Au, were employed as electrode materials for rectifying contacts. An ohmic contact was created on the entire opposite surface of the crystals by chemical deposition of Au from a gold chloride solution. The surface processing of CdTe crystals before the formation of both rectifying and ohmic contacts included mechanical and chemical polishing, as well as Ar-ion bombardment. Dark currents at reverse voltage of 1500 V did not exceed 4 nA for all the diodes except for the Au/CdTe/Au structure. The effect of the metal nature on the I-V characteristics and charge carrier transport mechanisms was studied, and the features of voltage dependences of dark current were explained by differences in the work functions of the metals, as well as the contact deposition technique.