Search NASA⌕ Search

SEARCH · Search NASA

Results for “Neutron Detection”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

ALPHANSO: Open-source modeling of (α, n) neutron source terms

Applications ranging from nuclear safeguards to dark matter detection require accurate predictions of neutron yields and energy spectra produced by (α, n) reactions. Legacy tools like SOURCES-4C remain widely used despite significant limitations, including outdated nuclear data, missing target nuclides, and restricted accessibility. Here, we present ALPHANSO, an open-source Python package for calculating (α, n) neutron source terms. ALPHANSO incorporates modern nuclear data libraries and formats covering all naturally occurring target nuclides and provides a transparent, modular framework for updating or extending the data as new evaluations are released. Comparison with an updated version of SOURCES-4A, NeuCBOT, and experimental measurements across a range of elements and materials shows that ALPHANSO reproduces neutron yields and spectra in good agreement with experimental data and state-of-the-art (α, n) calculations. These results demonstrate that ALPHANSO is a reliable, accessible, and modern alternative to legacy (α, n) source term codes such as SOURCES-4C. Its open-source design and modular data handling make it readily extensible to future evaluated nuclear data and low-background applications.

(α, n) reactions↗
NASA NTRS1985

SONTRAC: A solar neutron track chamber detector

The recent detection on the solar maximum mission (SMM) satellite of high energy neutrons emitted during large solar flares has provided renewed incentive to design a neutron detector which has the sensitivity, energy resolution, and time resolution to measure the neutron time and energy spectra with sufficient precision to improve our understanding of the basic flare processes. Over the past two decades a variety of neutron detectors has been flown to measure the atmospheric neutron intensity above 10 MeV and to search for solar neutrons. The SONTRAC (Solar Neutron Track Chamber) detector, a new type of neutron detector which utilizes n-p scattering and has a sensitivity 1-3 orders of magnitude greater than previous instruments in the 20-200 MeV range is described. The energy resolution is 1% for neutron kinetic energy, T sub n 50 MeV. When used with a coded aperture mask at 50 m (as would be possible on the space station) an angular resolution of approx. 4 arc sec could be achieved, thereby locating the sites of high energy nuclear interactions with an angular precision comparable to the existing x-ray experiments on SMM. The scintillation chamber is investigated as a track chamber for high energy physics, either by using arrays of scintillating optical fibers or by optical imaging of particle trajectories in a block of scintillator.

Frye, G. M., Jr.↗
NASA NTRSDate not supplied

1D Projections Readout and Track Reconstruction for the SONTRAC Instrument

Neutron spectroscopy and imaging has improved considerably over the last decade with the advancement of modern scintillating materials and compact, low power readout devices. Though challenging to detect, fast (>0.5 MeV) neutrons are ubiquitous, contribute to the radiation exposure of astronauts and space hardware, and have been effectively used to examine physical processes both locally and within our heliosphere at large. The SOlar Neutron TRACking (SONTRAC) instrument is designed to measure neutrons between 20-200 MeV with good angular sensitivity. SONTRAC consists of orthogonally stacked scintillating fibers readout by silicon photomultipliers to detect and track the recoil protons from double scatter neutron events. Proton tracking provides high-resolution imaging of fast neutronsat energies where the bulk of solar and planetary neutrons resides. The SONTRAC readout system, algorithms for track reconstruction, and tracking performance are presented.

George Suarez↗
DOE OSTI2026

Chasing Gamma-Ray Signals from Binary Neutron Star Coalescences with the Cherenkov Telescope Array: Prospects and Observing Strategies

The detection of gravitational waves (GWs) from a binary neutron star (BNS) merger by Advanced LIGO and Advanced Virgo (GW170817), together with its electromagnetic counterpart, the short gamma-ray burst GRB 170817A, heralded the birth of multimessenger astronomy. The detection of TeV emission from GRBs motivates follow-up observations with the Cherenkov Telescope Array Observatory (CTAO), which is ideal for detecting such signals due to its unprecedented sensitivity, rapid response, and wide-field survey capabilities. The aim of this work is to evaluate GeV–TeV GW follow-up strategies for CTAO using a multistep simulation pipeline and to estimate the expected rate of joint GW–GRB detections during observing run O5. Using a simulated sample of BNS systems with corresponding GW detections, gamma-ray emission is simulated through phenomenological prescriptions based on the observed population of short GRBs, including off-axis jet scenarios. CTAO observations are simulated to account for instrument response, sky tiling strategies, integration times, and varying observing conditions. Strategies with variable and constant integration times are investigated. We find that, via an optimized follow-up strategy, about 5% of simulated GW-associated short GRBs produce GeV–TeV radiation detectable by CTAO. Detectability is strongly influenced by the jet opening angle and viewing angle, suggesting that even rough estimates of the viewing angle in GW alerts could enhance targeting. This framework motivates future follow-ups of GW-detectable events, including neutron star–black hole mergers, and further supports the development of advanced strategies incorporating galaxy distributions and synergies with future detectors such as the Einstein Telescope.

Abe, S. [University of Tokyo] (ORCID:0000000172503↗
DOE OSTI2024

Boron-10 Doped Polysiloxanes as Matrix Materials for Application in the Simultaneous Detection and Discrimination of Gamma Rays and Fast and Thermal Neutrons

Three boron-10 enriched aromatic molecules have been synthesized and incorporated into two different commercial polysiloxane resins, Shin Etsu KER-6000 and Wacker SilRes H62-C. Scintillating fluorophores, 9,9-dimethyl-2-phenylfluorene (PhF) and 2,5-diphenyloxazole (PPO), were tested in combination with each resin and boron-10 molecule for the simultaneous detection of gamma rays, fast neutrons, and thermal neutrons. Here, the H62-C resin was able to solubilize a large amount of PhF, in excess of 20 wt%. Cure kinetics were controlled through the addition of divinylbenzene and phenyl tris(dimethylsiloxy)silane cross-linker solution to the H62-C resin, with rheology experiments demonstrating a large reduction in time to gelation when 20 wt% cross-linker solution was added, from more than 4 hours to less than 1 hour. These polysiloxane resins can be cured in 3 hours under air, while common poly(vinyltoluene) scintillators require at least 4 days of heating and oxygen-free conditions. PhF-doped KER-6000 with tolyl boronate pinacol ester exhibited the best overall performance with a light yield of 62% relative to EJ-200 and thermal neutron capture at energies up to 103 keVee (84 keVee for EJ254B-5). Additionally, four samples exhibited light yields surpassing an industry-standard boron-doped plastic scintillator, Eljen’s EJ254B-5. Over the course of ten months, the KER-6000 samples showed precipitation of dopant molecules, which reduced their light yield by 15% on average, while H62-C proved to be more stable with only a 6% reduction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1988

Neutrinos from SN 1987A and cooling of the nascent neutron star

The implications of the detection of neutrinos from SN 1987A for the cooling of the nascent neutron star are considered. The nu-bar(e) number N, the apparent temperature, the cooling time scale measured by the Kamioka and IMB detectors, and the inferred neutron star apparent radius and binding energy are all found to provide striking verification of current supernova theory.

Lamb, D. Q.↗
NASA NTRS2010

MCNP Simulations of Measurement of Insulation Compaction in the Cryogenic Rocket Fuel Tanks at Kennedy Space Center by Fast/Thermal Neutron Techniques

MCNP simulations have been run to evaluate the feasibility of using a combination of fast and thermal neutrons as a nondestructive method to measure of the compaction of the perlite insulation in the liquid hydrogen and oxygen cryogenic storage tanks at John F. Kennedy Space Center (KSC). Perlite is a feldspathic volcanic rock made up of the major elements Si, AI, Na, K and 0 along with some water. When heated it expands from four to twenty times its original volume which makes it very useful for thermal insulation. The cryogenic tanks at Kennedy Space Center are spherical with outer diameters of 69-70 feet and lined with a layer of expanded perlite with thicknesses on the order of 120 cm. There is evidence that some of the perlite has compacted over time since the tanks were built 1965, affecting the thermal properties and possibly also the structural integrity of the tanks. With commercially available portable neutron generators it is possible to produce simultaneously fluxes of neutrons in two energy ranges: fast (14 Me V) and thermal (25 me V). The two energy ranges produce complementary information. Fast neutrons produce gamma rays by inelastic scattering, which is sensitive to Fe and O. Thermal neutrons produce gamma rays by prompt gamma neutron activation (PGNA) and this is sensitive to Si, Al, Na, K and H. The compaction of the perlite can be measured by the change in gamma ray signal strength which is proportional to the atomic number densities of the constituent elements. The MCNP simulations were made to determine the magnitude of this change. The tank wall was approximated by a I-dimensional slab geometry with an 11/16" outer carbon steel wall, an inner stainless wall and 120 cm thick perlite zone. Runs were made for cases with expanded perlite, compacted perlite or with various void fractions. Runs were also made to simulate the effect of adding a moderator. Tallies were made for decay-time analysis from t=0 to 10 ms; total detected gamma-rays; detected gamma-rays from thermal neutron reactions d. detected gamma-rays from non-thermal neutron reactions and total detected gamma-rays as a function of depth into the annulus volume. These indicated a number of possible independent metrics of perlite compaction. For example the count rate for perlite elements increased from 3600 to 8500 cps for an increase in perlite density from 6 lbs/lcf to 16.5 lbs/cf. Thus the MCNP simulations have confirmed the feasibility of using neutron methods to map the compaction of perlite in the walls of the cryogenic tanks.

Livingston, R. A.↗
DOE OSTI2025

Neutron stars and the dense matter equation of state

The past two decades have witnessed tremendous progress in understanding the properties of neutron stars, their maximum mass and radii, and the properties of the dense matter in their cores, made possible by electromagnetic observations of neutron stars and the detection of gravitational waves from their mergers. These observations have provided novel constraints on neutron-star structure that are intimately related to the properties of dense neutron-rich matter described by the nuclear equation of state. Nevertheless, constraining the equation of state over the wide range of densities probed by astrophysical observations is still challenging, as the physics involved is broad and the system spans many orders of magnitude in density. Here, theoretical approaches to calculate and model the neutron-star equation of state in various regimes of densities are reviewed, and the related consequent properties of neutron stars are discussed. How the equation of state at low densities can be calculated from nuclear interactions that are constrained and benchmarked by nuclear experiments is described. Neutron-star observations, with a particular emphasis on information provided by gravitational-wave signals and electromagnetic observations, are reviewed. Finally, future challenges and opportunities in the field are discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

The Dynamics of Debris Disk Creation in Neutron Star Mergers

Abstract The detection of GW170817/AT2017gfo inaugurated an era of multimessenger astrophysics, in which gravitational-wave and multiwavelength photon observations complement one another to provide unique insight into astrophysical systems. A broad theoretical consensus exists, in which the photon phenomenology of neutron star mergers largely rests upon the evolution of the small amount of matter left on bound orbits around the black hole or massive neutron star remaining after the merger. Because this accretion disk is far from inflow equilibrium, its subsequent evolution depends very strongly on its initial state, yet very little is known about how this state is determined. Using both snapshot and tracer particle data from a numerical relativity/MHD simulation of an equal-mass neutron star merger that collapses to a black hole, we show how gravitational forces arising in a nonaxisymmetric, dynamical spacetime supplement hydrodynamical effects in shaping the initial structure of the bound debris disk. The work done by hydrodynamical forces is ∼10 times greater than that due to time-dependent gravity. Although gravitational torques prior to remnant relaxation are an order of magnitude larger than hydrodynamical torques, their intrinsic sign symmetry leads to strong cancellation; as a result, hydrodynamical and gravitational torques have a comparable effect. We also show that the debris disk’s initial specific angular momentum distribution is sharply peaked at roughly the specific angular momentum of the merged neutron star’s outer layers, a fewr g c, and identify the regulating mechanism.

Astronomy & Astrophysics↗
DOE OSTI2024

First measurement in a magnetic confinement fusion experiment of the H 3 + H 3 → He 5 + n intermediate two-body resonant reaction

We report on the first experimental measurements made at a magnetic confinement fusion device of the tritium(T)-tritium(T) reaction T + T → He 4 + 2 n indicating the presence of the intermediate two-body resonant reaction T + T → He 5 + n . During the second deuterium-tritium campaign (DTE2) at the Joint European Torus, measurements of fusion plasmas with high tritium concentrations, n T / ( n T + n D ) ≈ 0.99 , heated with tritium neutral beam injection, were performed using the neutron time-of-flight (TOF) spectrometer TOFOR. We detect a peak in the neutron emission TOF spectrum consistent with the two-body resonant reaction. The TT neutron emission energy spectrum is modeled using an R -matrix framework where the distributions of the most likely model parameters given our experimental TOF data are determined utilizing a Markov chain Monte Carlo approach. We compare our best estimate of the T + T neutron emission energy spectrum with results obtained at inertial confinement fusion experiments at the OMEGA facility and find a spectral shape that is consistent with the energy dependency in the neutron spectrum observed at OMEGA. Published by the American Physical Society 2024

Physics↗
NASA NTRS1978

Gamma-ray lines from neutron stars as probes of fundamental physics

The detection of gamma-ray lines produced at the surface of neutron stars will serve to test both the strong and gravitational interactions under conditions unavailable in terrestrial laboratories. Observation of a single redshifted gamma-ray line, combined with an estimate of the mass of the star will serve as a strong constraint on allowable equations of state of matter at supernuclear densities. Detection of two redshifted lines arising from different physical processes at the neutron star surface can provide a test of the strong principle of equivalence. Expected fluxes of nuclear gamma-ray lines from accreting neutron stars were calculated, including threshold, radiative transfer and redshift effects. The most promising probes of neutron star structure are the deuterium formation line and the positron annihilation line. Detection of sharp redshifted gamma-ray lines from X-ray sources such as Cyg X-1 would argue strongly in favor of a neutron star rather than black hole identification for the object.

Brecher, K.↗
DOE OSTI2026

Nuclear recoil detection with color centers in bulk lithium fluoride

We present initial results on the detection of nuclear recoils in lithium fluoride (LiF) through the fluorescence of color centers created by particle interactions in the crystal lattice. Using light-sheet fluorescence microscopy, we image nuclear recoil tracks from both fast and thermal neutron interactions deep within a cubic-centimeter-scale sample. Automated three-dimensional feature extraction based on machine-learning tools enables the identification and classification of individual events. We observe that the fluorescence response of LiF to gamma irradiation is strongly suppressed, by a factor of 30–50 compared to neutron exposure, demonstrating intrinsic insensitivity to electromagnetic backgrounds. The observed and simulated event characteristics are consistent, including their number, size, and topology. These results establish the feasibility of LiF as a scalable detection medium for rare nuclear-recoil events and constitute a first step toward 10–1000 g scale detectors with single-event sensitivity for applications in reactor-neutrino detection, neutron spectroscopy, and dark matter searches.

Aroujo, G R [University of Zurich]↗
NASA NTRS1980

Origin of the 5 March 1979 gamma-ray transient - A vibrating neutron star

An unusual gamma-ray transient was observed on 5 March 1979, with 12 different instruments on 9 different spacecraft. The source position of the 5 March transient, determined to an accuracy of 1 x 2 arcmin, is consistent with the direction of the supernova remnant N49 in the Large Magellanic Cloud (LMC). Subsequent analysis of the data, by narrowing the source error box to an area of about 6 by 30 arcsec inside the supernova remnant, considerably strengthens this identification. It is proposed that a vibrating neutron star in the LMC is the source of the 5 March transient. This may be both the first detection of a vibrating neutron star and indirect evidence for gravitation radiation.

Ramaty, R.↗
NASA NTRS1973

Evaluation of radioisotope tracer and activation analysis techniques for contamination monitoring in space environment simulation chambers

Radioisotope measurement techniques and neutron activation analysis are evaluated for use in identifying and locating contamination sources in space environment simulation chambers. The alpha range method allows the determination of total contaminant concentration in vapor state and condensate state. A Cf-252 neutron activation analysis system for detecting oils and greases tagged with stable elements is described. While neutron activation analysis of tagged contaminants offers specificity, an on-site system is extremely costly to implement and provides only marginal detection sensitivity under even the most favorable conditions.

Smathers, J. B.↗
DOE OSTI2025

First simultaneous measurement of the γ-ray and neutron emission probabilities in inverse kinematics at a heavy-ion storage ring

The probabilities for γ-ray and particle emission as a function of the excitation energy of a decaying nucleus are valuable observables for constraining the ingredients of the models that describe the deexcitation of nuclei near the particle emission threshold. These models are essential in nuclear astrophysics and applications. In this paper, we have for the first time simultaneously measured the γ-ray and neutron emission probabilities of 208 Pb. The measurement was performed in inverse kinematics at the Experimental Storage Ring (ESR) of the GSI/FAIR facility, where a 208 Pb beam interacted through the 208 Pb (p,p') reaction with a hydrogen gas jet target. Instead of detecting the γ rays and neutrons emitted by 208 Pb, we detected the heavy beamlike residues produced after γ and neutron emission. These heavy residues were fully separated by a dipole magnet of the ESR and were detected with outstanding efficiencies. The comparison of the measured probabilities with model calculations has allowed us to test and select different descriptions of the γ-ray strength function and the nuclear level density available in the literature.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Measurement of the free neutron lifetime in a magneto-gravitational trap with in situ detection

Here, in this study, we publish three years of data from the UCNτ experiment performed at the Los Alamos Ultracold Neutron Facility at the Los Alamos Neutron Science Center. These data are in addition to our previously published data. Our goals in this paper are to better understand and quantify systematic uncertainties and to improve the lifetime statistical precision. We previously reported a value from our 2017–2018 data for the neutron lifetime of 877.75 ± 0.28 (statistical) +0.22–0.16 (systematic) s. We have collected an additional three years of data reported here for the first time. When all the data from UCNτ are averaged for 2017, 2018, 2020, 2021, and 2022, we report an updated value for the lifetime of 877.83 ± 0.22 (statistical)+0.20–0.17 (systematic) s. We utilized improved monitor detectors, reduced our correction due to UCN upscattering on residual gas, and employed four different UCN detector geometries both to reduce the correction required for rate dependence and to explore potential contributions due to phase space evolution.

Cabibbo-Kobayashi-Maskawa matrix↗
DOE OSTI2024

Nuclear reactor radiation and temperature effects on piezoelectric surface acoustic wave devices

Surface acoustic wave (SAW) resonators were characterized in-situ in a nuclear reactor environment at high temperature. Devices based on lithium niobate (LiNbO 3 ), aluminum nitride (sc-AlN), and thin-film aluminum nitride on sapphire substrate (AlN/sapphire) were tested up to 400 °C temperature and 1.9 × 10 12 n/cm 2 s neutron flux. Shifts in device resonant frequency were detected in response to temperature and neutron flux. Devices undergo a frequency change when exposed to neutron flux. At 300 °C, AlN/sapphire produced the strongest neutron flux response about 1.02 ppm at 1.27 × 10 12 n/cm 2 s neutron flux (5.7 × 10 4 rad-Si/hr neutron dose rate), compared to 0.30 ppm for LiNbO 3 and 0.17 ppm for sc-AlN. While the transient kinetics in response to step change in neutron flux support the defect-accumulation mechanism, the concurrent measurement of device temperature using resistive temperature sensor suggests additional heating caused by absorption of gamma rays can also play a role. These results make SAW devices attractive candidates for sensor applications in extreme environments.

Aluminum nitride↗
NASA NTRS1995

Fission foil detector calibrations with high energy protons

Fission foil detectors (FFD's) are passive devices composed of heavy metal foils in contact with muscovite mica films. The heavy metal nuclei have significant cross sections for fission when irradiated with neutrons and protons. Each isotope is characterized by threshold energies for the fission reactions and particular energy-dependent cross sections. In the FFD's, fission fragments produced by the reactions are emitted from the foils and create latent particle tracks in the adjacent mica films. When the films are processed surface tracks are formed which can be optically counted. The track densities are indications of the fluences and spectra of neutrons and/or protons. In the past, detection efficiencies have been calculated using the low energy neutron calibrated dosimeters and published fission cross sections for neutrons and protons. The problem is that the addition of a large kinetic energy to the (n,nucleus) or (p,nucleus) reaction could increase the energies and ranges of emitted fission fragments and increase the detector sensitivity as compared with lower energy neutron calibrations. High energy calibrations are the only method of resolving the uncertainties in detector efficiencies. At high energies, either proton or neutron calibrations are sufficient since the cross section data show that the proton and neutron fission cross sections are approximately equal. High energy proton beams have been utilized (1.8 and 4.9 GeV, 80 and 140 MeV) for measuring the tracks of fission fragments emitted backward and forward.

Benton, E. V.↗