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At least 307 records · Page 17

A Concept for a High-Energy Gamma-ray Polarimeter

We present a concept for an imaging gamma-ray polarimeter operating from approx. 50 MeV to approx. 1 GeV. Such an instrument would be valuable for the study of high-energy pulsars, active galactic nuclei, supernova remnants, and gamma-ray bursts. The concept makes use of pixelized gas micro-well detectors, under development at Goddard Space Flight Center, to record the electron-positron tracks from pair-production events in a large gas volume. Pixelized micro-well detectors have the potential to form large-volume 3-D track imagers with approx. 100 micron (rms) position resolution at moderate cost. The combination of high spatial resolution and a continuous low-density gas medium permits many thousands of measurements per radiation length, allowing the particle tracks to be imaged accurately before multiple scattering masks their original directions. The polarization of the incoming radiation may then be determined from the azimuthal distribution of the electron-positron pairs. We have performed Geant4 simulations of these processes to estimate the polarization sensitivity as a function of instrument parameters and event selection criteria.

Bloser, P. F.↗

A position and pulse shape discriminant p -terphenyl detector module

We present the development of a neutron detector array module made with para-terphenyl, a bright, fast, n/γ discriminating crystalline organic scintillator. The module is comprised of 2 cm × 2 cm × 2 cm p-terphenyl crystals that have been optically coupled together to create a pseudo-bar module. While only relying on two photo detectors, the module is capable of distinguishing interactions between up to eight crystals. Furthermore, the module retains the p-terphenyl’s pulse shape discrimination (PSD) capability. Together this makes the pseudo-bar module a promising position-sensitive neutron detector. Here we present characteristics of the pseudo-bar module - its timing resolution as well as its pulse shape and position discrimination capabilities, and briefly discuss future plans for utilizing an array of pseudo-bar modules in a useful neutron detector system.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Spectrum Unfolding with the MC-15

The Multiplicity Counter 15 tube detector or MC-15 is an optimized detector designed for use in the field. It is composed of 15 3 He tubes embedded in high density polyethylene (HDPE). Recent work has explored expanding the use of the MC-15 beyond multiplicity counting to neutron dosimetry applications. Knowledge of the neutron energy spectrum information is required to use a detector as a neutron dosimeter. The MC-15 tube layout is shown in Figure 1. The unique layout makes it possible to use the detector for neutron spectroscopy via spectrum unfolding. Spectrum unfolding requires (1) energy dependence of the detector response, (2) a detector response matrix that precisely quantifies the response to mono-energetic neutrons, (3) an initial guess spectrum, (4) an unfolding algorithm, and (5) measured data (counts in the case of the MC-15). An energy dependent detector response matrix (DRM) can be constructed by considering either each of the three rows of 3 He tubes as a distinct detector or each individual tube as a distinct detector. The HDPE separating the 3 He in the MC-15 provides the distinct energy dependent response for the rows and individual tubes. In this report we detail the development of detector response matrices for the MC-15 and the application of the Los Alamos Unfolding Code (LUC) to both simulated and measured data. Three MC-15 orientations were studied: (1) standard orientation with the MC-15 front facing the source, (2) standard orientation with Cd sheet, (3) 90° orientation with the side of the MC-15 facing the source.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Shortwave infrared 512 x 2 line sensor for earth resources applications

As part of the NASA remote-sensing Multispectral Linear Array Program, an edge-buttable 512 x 2 IRCCD line image sensor with 30-micron Pd2Si Schottky-barrier detectors is developed for operation with passive cooling at 120 K in the 1.1-2.5 micron short infrared band. On-chip CCD multiplexers provide one video output for each 512 detector band. The monolithic silicon line imager performance at a 4-ms optical integration time includes a signal-to-noise ratio of 241 for irradiance of 7.2 microwatts/sq cm at 1.65 microns wavelength, a 5000 dynamic range, a modulation transfer function, greater than 60 percent at the Nyquist frequency, and an 18-milliwatt imager chip total power dissipation. Blemish-free images with three percent nonuniformity under illumination and nonlinearity of 1.25 percent are obtained. A five SWIR imager hybrid focal plane was constructed, demonstrating the feasibility of arrays with only a two-detector loss at each joint.

Tower, J. R.↗

Solid Cherenkov detector for studying nucleosynthesis in inertial confinement fusion

Measuring gamma rays emitted from nuclear reactions gives insight into their nuclear structure. Notably, there are several nuclear reactions that produce gamma rays at ~1 MeV–3 MeV energies such as T( 4 He, γ) 7 Li, 4 He( 3 He, γ) 7 Be, and 12 C(p, γ) 13 N, which may solve questions lingering about big-bang nucleosynthesis and stellar nucleosynthesis. To observe 1 MeV–3 MeV gamma rays in an inertial confinement fusion system, a new style of the Cherenkov detector was developed using aerogel and fused silica as a Cherenkov medium. Utilizing the OMEGA laser facility, both aerogel and fused silica media were compared with the existing gas-medium Cherenkov detector to validate the concept. Furthermore, gamma ray measurements from high yield inertial confinement fusion implosions (deuterium–tritium and deuterium– 3 He) demonstrated that aerogel and fused silica were viable Cherenkov media, paving the way for a potential optimized detector to make these cross section measurements on OMEGA or the National Ignition Facility.

47 OTHER INSTRUMENTATION↗

Scintillation light detection in polycrystalline diamond using single photon detectors

Here, this study investigates the scintillation properties of polycrystalline diamond for particle detection applications, particularly in neutron and alpha radiation environments. Polycrystalline diamonds provide a cost-effective alternative to monocrystalline diamonds while retaining essential detection properties. Photoluminescence measurements were performed to analyze emission spectra, revealing distinct characteristics based on impurity content and crystallinity. Scintillation responses were assessed using Silicon Photomultipliers (SiPMs), demonstrating the capability of polycrystalline diamond powders to respond to alpha irradiation, albeit with reduced resolution compared to traditional scintillators. A prototype neutron detector was developed by combining diamond powder with neutron-sensitive 6 LiF, and its performance was evaluated through experimental testing and Geant4 simulations. The findings indicate that polycrystalline diamond-based detectors can achieve significant detection efficiency while remaining insensitive to gamma radiation, offering potential for portable neutron detection applications.

47 OTHER INSTRUMENTATION↗

A novel electron tunneling infrared detector

The pneumatic infrared detector, originally developed by Golay in the late 1940s, uses the thermal expansion of one cm(exp 3) of xenon at room temperature to detect the heat deposited by infrared radiation. This detector was limited by thermal fluctuations within a 10 Hz bandwidth, but suffered from long thermal time constants and a fragile structure. Nevertheless, it represents the most sensitive room temperature detector currently available in the long wavelength infrared (LWIR). Fabrication of this type of detector on smaller scales has been limited by the lack of a suitably sensitive transducer. Researchers designed a detector based on this principle, but which is constructed entirely from micromachined silicon, and uses a vacuum tunneling transducer to detect the expansion of the trapped gas. Because this detector is fabricated using micromachining techniques, miniaturization and integration into one and two-dimensional arrays is feasible. The extreme sensitivity of vacuum tunneling to changes in electrode separation will allow a prototype of this detector to operate in the limit of thermal fluctuations over a 10 kHz bandwidth. A calculation of the predicted response and noise of the prototype is presented with the general formalism of thermal detectors. At present, most of the components of the prototype have been fabricated and tested independently. In particular, a characterization of the micromachined electron tunneling transducer has been carried out. The measured noise in the tunnel current is within a decade of the limit imposed by shot noise, and well below the requirements for the operation of an infrared detector with the predicted sensitivity. Assembly and characterization of the prototype infrared detector will be carried out promptly.

Kenny, T. W.↗

The detection of marine microseismic activity with the CUORE tonne-scale cryogenic experiment

Vibrations from experimental setups and the environment are a persistent source of noise for low-temperature calorimeters searching for rare events, including neutrinoless double beta ( 0νββ ) decay or dark matter interactions. Such noise can significantly limit experimental sensitivity to the physics case under investigation. Here, we report the detection of marine microseismic vibrations using mK-scale calorimeters. This study employs a multi-device analysis correlating data from CUORE, the leading experiment in the search for 0νββ decay with mK-scale calorimeters, and the Copernicus Earth Observation program, revealing the seasonal impact of Mediterranean Sea activity on CUORE’s energy thresholds, resolution, and sensitivity over four years. The detection of marine microseisms underscores the need to address faint environmental noise in ultra-sensitive experiments. Understanding how such noise couples to the detector and developing mitigation strategies is essential for next-generation experiments. We demonstrate one such strategy: a noise decorrelation algorithm implemented in CUORE using auxiliary sensors, which reduces vibrational noise and improves detector performance. Enhancing sensitivity to 0νββ decay and to rare events with low-energy signatures requires identifying unresolved noise sources, advancing noise reduction methods, and improving vibration suppression systems, all of which inform the design of next-generation rare event experiments.

experimental nuclear physics↗

Proportional counter for X-ray analysis of lunar and planetary surfaces

A position sensitive proportional scintillation detector was developed and evaluated for use in applications involving X-ray imaging as well as spectroscopy. Topics covered include limitations of the proportional scintillation counter for use in space; purification of the xenon gas in the detector, and the operation of the detector system. Results show that the light signal in a proportional scintillation detector remains well localized. With modest electric fields in xenon, the primary electrons from a photoelectric absorption of an X-ray can be brought a distance of a few millimeters to a higher field region without spreading more than a millimeter or so. Therefore, it is possible to make a proportional scintillation detector with good position sensitivity that could be used to calibrate out the difference in light collection over its sensitive volume.

Source record↗

Recent progress with multi-anode microchannel array detector systems

The construction and modes of operation of Multi-Anode Microchannel Arrays (MAMA's) are briefly reviewed. The MAMA detectors, which are a family of photoelectric, photon-counting array detectors being developed specifically for use in instruments on ground-based and space-borne telescopes, combine the high sensitivity and photometric stability of a conventional channel electron multiplier with a high-resolution imaging capability. The MAMA detectors feature low applied potential (less than 3 kV), high gain (greater than 10 to the 6th electrons/pulse), an absolute event timing accuracy of 100 ns or better, a very long count lifetime (greater than 2.5 x 10 to the 11th counts/sq mm), and a power consumption of less than 30 W for a complete system

Timothy, J. G.↗

Charge-coupled-device X-ray detector performance model

A model that predicts the performance characteristics of CCD detectors being developed for use in X-ray imaging is presented. The model accounts for the interactions of both X-rays and charged particles with the CCD and simulates the transport and loss of charge in the detector. Predicted performance parameters include detective and net quantum efficiencies, split-event probability, and a parameter characterizing the effective thickness presented by the detector to cosmic-ray protons. The predicted performance of two CCDs of different epitaxial layer thicknesses is compared. The model predicts that in each device incomplete recovery of the charge liberated by a photon of energy between 0.1 and 10 keV is very likely to be accompanied by charge splitting between adjacent pixels. The implications of the model predictions for CCD data processing algorithms are briefly discussed.

Bautz, M. W.↗

Materials for Gamma Radiation Sensors

Sensors used for spectroscopic measurements of gamma radiation are most often scintillator or semiconductor materials. An overview is provided in this chapter on the materials and development techniques used in producing spectroscopic gamma radiation sensors. Challenges that prevent a perfect sensor are discussed along with the reasons why some sensor materials are ubiquitous despite their performance limitations. The types of sensors commonly used as detectors are discussed along with their key physical properties and electronic characteristics. Materials commonly utilized in radiation detectors are then reviewed to highlight how sensor materials have advanced since the earliest gamma detectors were developed

Johns, Paul M.↗

Laboratory characterization of direct readout Si:Sb and Si:Ga infrared detector arrays

Highlights of recent results obtained at Ames Research Center in performance evaluations of infrared detector arrays are presented. Antimony- and gallium-doped silicon direct readout 58x62 element hybrid devices from Ames' ongoing detector technology development program are described. The observed characteristics meet most of the performance goals specified by the Space Infrared Telescope Facility (SIRTF) instrument teams and compare favorably with the best performance reported for discrete non-integrating extrinsic silicon detectors. Initial results of radiation environment testing are reported, and non-ideal behavior demonstrated by these test devices is discussed.

Mckelvey, Mark E.↗

GaN-Based Detector Enabling Technology for Next Generation Ultraviolet Planetary Missions

The ternary alloy AlN-GaN-InN system provides several distinct advantages for the development of UV detectors for future planetary missions. First, (InN), (GaN) and (AlN) have direct bandgaps 0.8, 3.4 and 6.2 eV, respectively, with corresponding wavelength cutoffs of 1550 nm, 365 nm and 200 nm. Since they are miscible with each other, these nitrides form complete series of indium gallium nitride (In(sub l-x)Ga(sub x)N) and aluminum gallium nitride (Al(sub l-x)Ga(sub x)N) alloys thus allowing the development of detectors with a wavelength cut-off anywhere in this range. For the 2S0-365 nm spectral wavelength range AlGaN detectors can be designed to give a 1000x solar radiation rejection at cut-off wavelength of 325 nm, than can be achieved with Si based detectors. For tailored wavelength cut-offs in the 365-4S0 nm range, InGaN based detectors can be fabricated, which still give 20-40x better solar radiation rejection than Si based detectors. This reduced need for blocking filters greatly increases the Detective Quantum efficiency (DQE) and simplifies the instrument's optical systems. Second, the wide direct bandgap reduces the thermally generated dark current to levels allowing many observations to be performed at room temperature. Third, compared to narrow bandgap materials, wide bandgap semiconductors are significantly more radiation tolerant. Finally, with the use of an (AI, In)GaN array, the overall system cost is reduced by eliminating stringent Si CCD cooling systems. Compared to silicon, GaN based detectors have superior QE based on a direct bandgap and longer absorption lengths in the UV.

Aslam, S.↗

Research and Development Related to the Commercialization of Perovskite Radiation Detectors (CRADA Final Report)

This work will focus on the development of perovskite radiation detectors fabricated with nanocrystal, thick polycrystalline films, or single crystal materials. This will harness NREL’s instrumentation and expertise in a variety of research areas including but not limited to metal halide perovskites, device characterization, device packaging, accelerated lifetime testing, and ink chemistry development.

14 SOLAR ENERGY↗

Detector Materials Scoping Study: Research and Development Recommendations

Radiation detection materials have a unique role in many nuclear security missions. The variety of different applications requires the use of different materials whose characteristics are determined by the specific application requirements. While baseline capabilities have been established to use radiation detection in these applications, the potential to greatly advance those capabilities still exists through the development of superior radiation detection materials and/or the development of new materials that enable new technologies to be implemented more effectively. In 2024 the Defense Nuclear Nonproliferation Research and Development (DNN R&D) Near Field Detection Portfolio charged a detector materials scoping study, composed of a group of radiation-detection materials subject matter experts, to produce a community-wide consensus view of the current state of radiation materials research and to set recommendations for expanded investment over a ten-year time frame. This scoping study sought to understand and document the landscape of how radiation detection materials are used, what characteristics drive the selection of various materials, and what developments are needed to drive the state of the art. To respond to this charge, the scoping study created three working groups, each focusing on a different topical area in radiation detection materials research - Semiconductor Materials, Inorganic Scintillators and Organic Scintillators - with the task to identify the current state of the art in materials research and to provide mission-relevant research and development recommendations. Each working group was chaired by two members of the project team with widely recognized expertise in the field. Solicitations were sent out to experts at the DOE national laboratories, industry, academia and federal government agencies to participate in these working groups. The working groups met at regular intervals throughout 2024 and early 2025, each delivering a technical roadmap designed to enable the pursuit of R&D more intensely on high-impact materials challenges and detector solutions that are deemed as the greatest strategic value to DNN R&D and its stakeholders. The roadmap is also intended to help communicate recommended programmatic priorities within DNN R&D and across the nonproliferation and research communities.

36 MATERIALS SCIENCE↗

Near Detector Selection for Neutral Current Disappearance Search at the Short-Baseline Neutrino Program

Various short baseline neutrino experiments observe anomalies that challenge the three-flavor neutrino oscillation model, consistent with a hypothetical “sterile” neutrino that does not interact via the weak force. This poster presents a near detector event selection at the Short-Baseline Near Detector (SBND), developed for the first search for neutral current (NC) disappearance at short-baseline experiments. NC disappearance provides ``smoking gun” insight into the sterile neutrino question because NC interactions are equally sensitive to all three active neutrinos, meaning any change in the NC interaction rate between near and far detectors cannot be explained by oscillations among known flavor states. This analysis focuses on the NC1p topology, the most common NC interaction type at the Short-Baseline Neutrino (SBN) Program. NC topologies are inherently challenging due to their low light yield and the absence of an outgoing charged lepton, which complicates identification and leads to poor energy reconstruction as the outgoing neutrino carries away a large portion of the neutrino’s initial energy. This work presents an NC1p event selection at the near detector, highlighting SBND’s impressive detector capabilities, including trigger efficiency studies. Combined with a novel kinematic energy reconstruction technique leveraging the detector’s outstanding hadronic detail, this analysis establishes a robust near detector foundation to target an NC disappearance measurement consistent with the 3$+$1 sterile neutrino model. This SBND selection will soon be combined with the far detector to conduct an NC disappearance search, providing unique insight and complementary information to traditional charged current searches and advancing the SBN Program’s goal to resolve the sterile neutrino question, including 3$+$1 searches and beyond.

Nicole Pallat, Nicole Pallat [Minnesota U.] (ORCID↗

Measurement of the scintillation and ionization response of liquid xenon at MeV energies in the EXO-200 experiment

In this work, liquid xenon (LXe) is employed in a number of current and future detectors for rare event searches. We use the EXO-200 experimental data to measure the absolute scintillation and ionization yields generated by γ interactions from 228 Th (2615 keV), 226 Ra (1764 keV), and 60 Co (1332 keV and 1173 keV) calibration sources, over a range of electric fields. The W value that defines the recombination-independent energy scale is measured to be 11.5±0.5 (syst.) ±0.1 (stat.) eV. These data are also used to measure the recombination fluctuations in the number of electrons and photons produced by the calibration sources at the MeV scale, which deviate from extrapolations of lower-energy data. Additionally, a semiempirical model for the energy resolution of the detector is developed, which is used to constrain the recombination efficiency, i.e., the fraction of recombined electrons that result in the emission of a detectable photon. Detailed measurements of the absolute charge and light yields for MeV-scale electron recoils are important for predicting the performance of future neutrinoless double β -decay detectors.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗