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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

An instrument for measuring the complex permittivity of the Martian top soil

This permittivity measuring instrument measures the resistivity rho and the relative dielectric constant epsilon sub r of the Martian top soil along the path of a rover. This aim is achieved by measuring the real and imaginary parts of the complex permittivity epsilon = epsilon sub r - j epsilon sub i where epsilon sub i = omega epsilon sub o rho/1; epsilon sub 1 is the permittivity of vacuum and omega is a variable angular working frequency. The experimental technique consists in evaluating the mutual, or transfer, impedance of a quadrupolar probe, i.e., in quantifying the influence of the Martian ground on the electrical coupling of two Hertz dipoles. The horizontal and vertical spatial resolutions are of the order of the length and separation of the dipoles, typically 1 to 2 metres. The four-electrode method for measuring the ground resistivity on earth was first applied by Wenner and Schlumberger, but the proposed investigation bears closer resemblance to a similar instrument developed for ground surveying at shallow depth, in connection with archaelogical and pedological research. A quadrupolar probe will provide essential information about the electric properties of the Martian ground and will contribute usefully to the identification of the soil structure and composition in association with other experimental equipment (camera, infra-red detector, gamma and X-ray spectrometers, chemical analyzers, ground temperature probes).

Grard, R.↗
NASA NTRS1991

Radioactivities of Long Duration Exposure Facility (LDEF) materials: Baggage and bonanzas

Radioactivities in materials onboard the returned Long Duration Exposure Facility (LDEF) satellite were studied by a variety of techniques. Among the most powerful is low background Ge semiconductor detector gamma ray spectrometry. The observed radioactivities are of two origins: those radionuclides produced by nuclear reactions with the radiation field in orbit and radionuclides present initially as contaminants in materials used for construction of the spacecraft and experimental assemblies. In the first category are experiment related monitor foils and tomato seeds, and such spacecraft materials as Al, stainless steel, and Ti. In the second category are Al, Be, Ti, Va, and some special glasses. Consider that measured peak-area count rates from both categories range from a high value of about 1 count per minute down to less than 0.001 count per minute. Successful measurement of count rates toward the low end of this range can be achieved only through low background techniques, such as used to obtain the results presented here.

Smith, Alan R.↗
DOE OSTI2022

A Tool Kit for Generating Simulated Radiation Measurements for Advanced Reactor Safeguards and Security

A tool kit was developed to simulate and analyze passive radiation measurements of molten salt reactor (MSR) operations to support development of nuclear safeguards approaches for this emerging reactor technology. A Transient Simulation Framework of Reconfigurable Modules (TRANSFORM) multiphysics simulation of an MSR produces time-dependent isotopic inventories at user-selected locations within the model. The tool kit implements the Gamma Detector Response and Analysis Software (GADRAS) application programming interface to inject the TRANSFORM isotopic inventories extracted/processed by a Python pipeline into GADRAS models of user-defined geometries. The TRANSFORM inventories are the source terms used to obtain synthetic measurements from GADRAS-defined detectors. The speed of TRANSFORM and GADRAS simulations enables surveying the large design space of MSRs (e.g., fuel type, fuel salt composition, number of loops) and the plethora of measurements (e.g., location, detector type, and collimation) within the reactor. This has enabled timely assessment of the various measurement locations and detectors to identify the most effective and efficient safeguards approach for a specific MSR design. Lastly, the tool kit also simulates extracted samples that can be aged to a desired dose, enabling stakeholders to optimize a measurement plan to use sample analysis as an element within a broader material accountancy plan.

Westphal, Greg↗
DOE OSTI2021

Simulation of Isotopic Concentrations and Gamma Spectra from Dynamic Fission Sources

A tool was developed to rapidly generate synthetic gamma-ray spectra to evaluate safeguards material control and accounting methods for liquid-fueled molten salt reactors. Molten salt reactor operations pose unique challenges to nuclear safeguards methods and protocols compared to deployed reactors designs (e.g., light water reactors). This research evaluates the use of gamma-ray spectroscopy to monitor fission product isotopic flow through a reactor model to understand expected operations and investigate changes to the spectra with material diversion scenarios. The large design space of molten salt reactors (e.g., liquid-fueled, liquid-cooled, online separations) could potentially lead to many measurement points within the reactor system. The developed analytical tool generates and evaluates synthetic gamma-ray spectra from dynamic reactor simulations by extracting isotopic inventory to generate source terms. An implementation in the Gamma Detector Response and Analysis Software (GADRAS) Application Program Interface (API) uses the source terms, a model of the reactor component, a detector response function, and measurement plan to quickly generate and analyze spectra. Prospective measurements are then evaluated in the more accurate but slower Geant4 simulations. Utilization of the developed modeling tool and analysis of the subsequent spectra enables optimization of collimation, shielding requirements, and expected count rates that are used to determine key measurement points in the modeled reactor design.

O'Brien, Sean↗
NASA NTRS2006

Characterization of Single-Sided Charge-Sharing CZT Strip Detectors for Gamma-Ray Astronomy

We report progress in the study of thick single-sided charge-sharing cadmium zinc telluride (CZT) strip detector modules designed to perform spectroscopy and 3-D imaging of gamma-rays. We report laboratory measurements including spectroscopy, efficiency and 3-D imaging capability of prototype detectors (15 15 7.5 cu mm) with 11x11 unit cells. We also report on Monte Carlo simulations (GEANT4 v7.1) to investigate the effect of multihits on detector performance in both spectroscopy and imaging. We compare simulation results with data obtained from laboratory measurements and discuss the implications for future strip detector designs. Keywords: CZT, strip detectors, gamma-ray

Donmez, Burcin↗
NASA NTRS1978

Capabilities of germanium detectors

The gamma ray detection efficiency and energy resolution of germanium detectors is reviewed. A general sensitivity equation for gamma-ray detectors is presented and calculated sensitvity curves are shown for a large volume balloon-borne spectrometer using germanium detectors. Improvement anticipated from a planned satellite experiment using germanium detectors is discussed.

Willett, J. B.↗
DOE OSTI2026

Evaluation of a deuterated detector for gamma-ray beam intensity measurements

Laser-Compton scattering sources of quasi-monochromatic γ-ray beams have been in operation for over 30 years, with new facilities being under construction or proposed. To sustain a high-quality experimental physics program, continuous monitoring of these beams is essential by measuring the spectral, temporal, and spatial characteristics. In this work, we introduce a new method for determining the γ-ray beam intensity by using photodisintegration of deuterons in an active target detector approach. Measurements were performed using deuterated liquid scintillator detectors at several incident gamma energies between 4 and 13 MeV at the High Intensity γ-ray Source, Durham, USA. The results demonstrate that an instrument based on a deuterated active detector can be used to monitor the intensity of the γ-ray beam with high efficiency and operational simplicity.

Compton scattering↗
NASA NTRSDate not supplied

Moon Burst Energetics All-sky Monitor: A Beyond Earth-orbit Gamma-ray Burst Detector for Multi-Messenger Astronomy

Moon Burst Energetics All-sky Monitor (MoonBEAM) is a gamma-ray mission in a cislunar orbit to observe the entire sky instantaneously for relativistic astrophysical explosions. It is designed to explore the behavior of matter and energy under extreme conditions by observing the prompt emission from gamma-ray bursts, identifying the conditions capable of launching transient relativistic jets and the origins of high-energy radiation from the relativistic outflows. MoonBEAM provides essential gamma-ray observations for multi-messenger astronomy by reporting on the prompt emission and providing rapid alerts to the astronomical community for contemporaneous and follow-up observations. In this era of multi-messenger astronomy, simultaneous broadband observations of relativistic transients are needed to construct a comprehensive picture of compact mergers and energetic phenomena, which is a key goal of the Astro2020 decadal survey theme New Windows on the Dynamic Universe. MoonBEAM provides the sensitive high-energy all-sky observation that is critical to transient and multi-messenger astronomy.

Gamma-rayburst↗
NASA NTRSDate not supplied

Moon Burst Energetics All-sky Monitor: A Beyond Earth-orbit Gamma-ray Burst Detector for Multi-Messenger Astronomy

- Moon Burst Energetics All-sky Monitor is 3-year gamma-ray mission in cislunar orbit to explore the behavior of matter and energy under extreme conditions by observing relativistic astrophysical explosions. - MoonBEAM provides key capabilities that are difficult to achieve in Low Earth Orbit: - instantaneous all-sky gamma-ray field of view - uninterrupted observations with >96% duty cycle - background radiation stability - 3 years of mission operation will provide observations of: - 1600 binary compact mergers - 5900 optically discovered core collapse supernovae - 140 magnetar giant flares - and enables 55 very high energy gamma-ray and 360 optical follow-up

gamma-ray burst↗
DOE OSTI2025

X-ray escape peaks in gamma-ray spectrum acquired by perovskite detector

The X-ray escape peaks are clearly visible in the high-resolution gamma spectra acquired by CsPbBr 3 , credit to the rapidly improving energy resolution of perovskite gamma detectors. But it also raises concerns. If this peak remains as significant as it is, perovskite gamma detectors would have very limited use in complex gamma spectrometry applications. This paper discusses the origin of the escape peaks in CsPbBr 3 detectors, benchmarked against Ge and CZT detectors. The Pb escape peak consists of four escape peaks that are merged together, while the Cs and Br escape peaks are hidden inside the photopeak of 137 Cs (662 keV). These combined effects either create a noticeable gamma peak observed to the left of the 662 keV photopeak when acquired using a high-resolution CsPbBr 3 detector or raise the left slope of the photopeak. We also explore potential methods to mitigate these peaks, such as applying anti-coincidence method. The height of the escape peaks diminishes as the detector volume increases but will not go away entirely. The relationship between the observed Pb escape peak and the detector's dimensions is demonstrated through Monte Carlo simulation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1993

The GAMCIT gamma ray burst detector

The GAMCIT payload is a Get-Away-Special payload designed to search for high-energy gamma-ray bursts and any associated optical transients. This paper presents details on the design of the GAMCIT payload, in the areas of battery selection, power processing, electronics design, gamma-ray detection systems, and the optical imaging of the transients. The paper discusses the progress of the construction, testing, and specific design details of the payload. In addition, this paper discusses the unique challenges involved in bringing this payload to completion, as the project has been designed, constructed, and managed entirely by undergraduate students. Our experience will certainly be valuable to other student groups interested in taking on a challenging project such as a Get-Away-Special payload.

Mccall, Benjamin J.↗
NASA NTRS1972

The response of covered silicon detectors to monoenergetic gamma rays

Measurements were made of the efficiency in detecting gamma rays of a 0.3-mm, a 3-mm, and a 5-mm silicon detector covered with different absorbers. Calibrated sources covering the range from 279 KeV to 2.75 MeV were used. The need for the absorbers in order to obtain meaningful results, and their contribution to detector response at electron biases from 50 to 200 KeV, are discussed in detail. It is shown that the results are independent of the atomic number of the absorber. In addition, the role of the absorber in increasing the efficiency with increasing photon energy for low bias setting is demonstrated for the 0.3-mm crystal. Qualitative explanations are given for the shapes of all curves of efficiency versus energy at each bias.

Reier, M.↗
NASA NTRS1972

The response of covered silicon detectors to monoenergetic gamma rays.

Measurements have been made of the efficiency in detecting gamma rays of a 0.3-mm-, 3-mm-, and 5-mm-thick silicon detector covered with different absorbers. Calibrated sources over the range from 279 keV to 2.75 MeV were used. The need for the absorbers to obtain meaningful results and their contribution to the response of the detectors at electron biases from 50 to 200 keV are discussed in detail. It is shown that the results are virtually independent of the atomic number of the absorber. In addition, the role of the absorber in increasing the efficiency with increasing photon energy for low bias settings is demonstrated for the 0.3-mm crystal. Qualitative explanations are given for the shapes of all curves of efficiency versus energy at each bias.

Reier, M.↗
NASA NTRS1992

The ionosphere as a gamma ray burst detector

Unlike all man made detectors, which are only sensitive to relative narrow regions of the electromagnetic spectrum, the ionosphere is practically a perfect detector for high energy radiation because it absorbs all radiation from the far-ultraviolet to the higher energy gamma-rays. Therefore, it may be possible to employ the terrestrial atmosphere as a detector of high energy celestial photons. As early as the 1940's solar flares were detected by the disturbance they caused to the ionosphere. The VLF (3 - 30 kHz) approach for detecting ionospheric disturbances is based on the following physical circumstance: celestial high energy radiation ionizes the atoms of the earth's ionosphere leading to the production of free electrons. These free electrons influence the propagation of electromagnetic waves. By studying the phase and amplitude changes of VLF radio wave propagating in the earth-ionosphere waveguide, it was hoped to ascertain the electron density in these regions and draw conclusions about the celestial radiation which caused them. To detect gamma-ray bursts, two conditions for the optimal detection are: (1) large zenith angle; and (2) alignment of burst and propagation path.

Mcgruder, Charles H., III↗
NASA NTRS2022

Pair Production Detectors for Gamma-ray Astrophysics

Electron-positron pair production is the essential process for high-energyγ-ray astrophysical observations. Following the pioneeringOSO-3counter telescope, the field evolved into use of particle tracking instruments, largely derived from high-energy physics detectors. Although many of the techniques were developed on balloon-borneγ-ray telescopes, the need to escape the high background in the at-mosphere meant that the breakthrough discoveries came from theSAS-2andCOS-Bsatellites. The next major pair production success was EGRET on the Comp-ton Gamma Ray Observatory, which provided the first all-sky map at energies above 100 MeV and found a variety ofγ-ray sources, many of which were vari-able. The current generation of pair production telescopes,AGILEandFermiLAT,have broadened high-energyγ-ray astrophysics with particular emphasis on multi-wavelength and multimessenger studies. A variety of options remain open for future missions based on pair production with improved instrumental performance.

Gamma rays↗