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Gamma Ray - OSTI GOV

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Last Updated: 03 September 2022

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Gamma-Ray Imaging to Monitor Accumulating Holdup

Over time, nuclear materials can accumulate in process equipment, and monitoring such data is of great importance to several stakeholder groups, such as safeguards, process control, criticality monitoring, and radiological protection. In this series, we replicated the deposition of largely enriched uranium in a large rectangular stainless-steel duct by stacking 5, 27 u00d7 50 cm2 cards, each of which has about 11 g of 235U in oxide form distributed across its surface, behind each other. Long integrations were established to allow for analyzing the approach's results as a function of integration time. The photographs were evaluated using first principles to determine the amount of material in each photograph. With a quantitative gamma-ray imaging system, the study provides a proof of concept for unattended monitoring of uranium holdup.

Source link: https://www.osti.gov/biblio/1883841


Flat-spectrum Radio Quasars and BL Lacs Dominate the Anisotropy of the Unresolved Gamma-Ray Background

We investigate the angular power spectrum of the unsolved gamma-ray background emission's unresolved gamma-ray background emission and integrate it with the measured characteristics of the Fermi-LaT 4FGL catalog's determined gamma-ray sources. We find that, under physical conditions for the spectral energy transfer, i. e. by using the 4FGL catalog data as a prior, two populations are required to fit the APS results, namely flat-spectrum radio quasars at low energies and BL Lacs at higher energies.

Source link: https://www.osti.gov/biblio/1844784


Evidence for a high-energy tail in the gamma-ray spectra of globular clusters

The most likely source of gamma-ray emission from globular clusters is millisecond pulsars. However, the relative contributions of two distinct emission processes, such as millisecond pulsar magnetospheres versus inverse Compton emission from relativistic pairs launched into the global cluster environment by millisecond pulsars u2013, have long been unclear. We're looking for signs of inverse Compton emission in 8-yr Fermi (UAT) data from 157 Milky Way globular clusters to answer this. We find a modestly statistically significant relationship between the measured globular cluster gamma-ray luminosities and their photon field energy densities. This may also be explained by a little-known correlation between the photon field densities and the stellar encounter rates of globular clusters, which may also be explained by a subtle connection. We are able to demonstrate that the gamma-ray emission of globular clusters can be resolved spectrally into two parts, an exponentially reduced power statute and a pure power statute, which were both demonstrated in Toto.

Source link: https://www.osti.gov/biblio/1837494


Development and validation of a gamma-ray detection response model for neutron-diagnosed subcritical experiments

In addition to a custom detector response model for use in forward modeling, a neutron-diagnosed subcritical experiment requires a highly sensitive and fast detector to accurately determine the true fission u03b3-ray emission rate from an object made of special nuclear material under interrogation. We discuss the design of a detector response system that is based in GEANT4 and incorporates post-processing methods to include photomultiplier tube time and pulse height response variations. These measurements and simulation results show that a large volume EJ-299-49 plastic scintillator that is attached to ultraviolet transmitting plastic light guide and depends on total internal reflection for light transport to the photocathode will achieve much faster timing, increase pulse height by a factor of three, and require 25% less rays to satisfy experimental requirements relative to the candidate detector configuration that was not available prior to the introduction of this response device.

Source link: https://www.osti.gov/biblio/1818109


Prospects for the observation of Primordial Black Hole evaporation with the Southern Wide field of view Gamma-ray Observatory

Our primordial Black Holes are remnants of objects that were created in the early Universe. This evaporation could result in a u3b3-ray flash that can be detected by the new generation of Very-High-Energy u03b3-ray detectors. The Southern Wide Field of view Gamma-ray Observatory will be one of the new generation of these instruments.

Source link: https://www.osti.gov/biblio/1873358


Signatures of Recent Cosmic-Ray Acceleration in the High-latitude Gamma-Ray Sky

If individual sources are close enough to the solar system, their localized enhancements may appear as features in the CR's measured spectra and associated secondary electromagnetic emissions. We look for extended enhanced emission associated with putative near CR sources in the energy range from 1 GeV to 1 TeV for the sky region, using a decade of data from Fermi Large Area Telescope, including Gaussian Processes. For the first time as a u03b3-ray emitter, Radio Loop IV is identified as a u03b3-ray emitter, and Loop I emits significant emission. In addition, good evidence has been found for asymmetric characteristics of the Galactic l = 0 0u00b0 meridian, which may be associated with elements of the so-called "Fermi Bubbles,'" and other radio loops, and some evidence for u03b3-ray emission from other radio loops.

Source link: https://www.osti.gov/biblio/1819497


Fabrication of Low-Cost Large-Volume Ceramic A 2 HfX 6 (A= Cs or Tl, X = Cl, Br, or I) Scintillators for Gamma Ray Detection. SBIR Phase I Final Technical Report

In addition, the cost for manufacturing a semiconductor detector like CdZnTe is typically less than that of manufacturing a semiconductor detector such as NaI:Tl. In Phase I, Xtallized Intelligence, Inc. developed a novel ceramic fabrication process that could produce low cost, environmentally friendly, and cost-effective inorganic transparent scintillators of various sizes. The findings of this Phase I research reveal that successful manufacture of high-quality inorganic halide ceramic scintillators Cs 2 HfCl 6 and Tl 2 HfCl 6. Both ceramic CHC and THC scintillators have delivered solid results close to their single crystal counterparts' results.

Source link: https://www.osti.gov/biblio/1774642


TlSr 2 I 5 :Eu 2+ - A new high density scintillator for gamma-ray detection

In this paper, we discuss the scintillation properties of TlSr 2 I 5 doped with Eu 2+, a novel thallium-containing high-resolution scintillator for gamma-ray spectroscopy. The X-ray excited emission of Eu 2+ doped TlSr 2 I 5 from Eu 2+ features a broad emission band peaking at 460 u2013470 nm. According to a TlSr 2 I 5 crystal doped with 1% Eu 2+'s light yield has been measured at 72,000 ph/MeV with an energy resolution of 2. 8 % at 662 kev.

Source link: https://www.osti.gov/biblio/1735452


MeV Gamma Rays from Fission: A Distinct Signature of Actinide Production in Neutron Star Mergers

The first confirmed locations of rapid neutron capture nucleosynthesis are identified in the neutron-rich ejecta, and they can release gamma rays from the radioactive isotopes synthesized in the neutron-rich ejecta. These MeV rays can provide a unique and direct glimpse into the NSM atmosphere as well as insight into the r process's architecture, as well as detailed insight into the r process, as observed gammas from the 56 Ni radioactive decay chain provide a window into supernova nucleosynthesis. For the first time in estimates of the Mev gamma-ray signal expected from an NSM event, we include photons from fission processes.

Source link: https://www.osti.gov/biblio/1736327


Self-organized criticality in multi-pulse gamma-ray bursts

Using a Markov Chain Monte Carlo approach, we investigate whether the self-organized criticality phenomena persist in each burst by testing the distributions of several common physical parameters, such as the isotropic energy E iso, the duration time T, and each pulse's peak count rate P. The findings of this report show that the jet responsible for the GRBs should be magnetically dominant, and that magnetic instability leads the GRB emission region to the SOC state.

Source link: https://www.osti.gov/biblio/1711397

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions