Search NASA⌕ Search

SEARCH · Search NASA

Results for “gamma-gamma coincidence”

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.

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Neutron activation analysis using gamma-gamma coincidence to eliminate spectral interferences

The use of neutron activation analysis (NAA) sometimes has limitations with the identification of specific gamma ray peaks due to spectral interferences. The implementation of gamma-gamma coincidence techniques using the XIA Pixie-16 system has demonstrated the ability reduce many of these challenges. In this work, experiments were performed on two different NIST reference materials using gamma-gamma coincidence techniques to identify long-lived radionuclides that are often difficult to evaluate due to various spectral interferences. The experiments have shown that utilizing gamma-gamma coincidence with the XIA Pixie-16 system for 177m Lu, 124 Sb, 160 Tb, 175 Yb, and 153 Sm can eliminate spectral interferences and high backgrounds due to Compton scattering.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Deployment of portable, modular gas samplers as part of an atmospheric tracer experiment

Underground nuclear explosions release noble gases into the atmosphere that can be detected to support international monitoring efforts. Atmospheric transport models help predict the movement of these gases over long distances, but struggle to predict the movement in the atmosphere local to the release. A field experiment was designed to monitor the movement of 127 Xe within a 5-km radius. Four gas samplers were deployed as part of this experiment to collect atmospheric samples at various distances from the release point. In conclusion, these samples were then analyzed in a near-field lab using a NaI detector and in an off-site lab using gamma-gamma coincidence and beta-gamma coincidence counting.

Radioxenon↗
DOE OSTI2025

Development and validation of a software for simulating γ-γ coincidence emission and detection probabilities

Gamma-gamma coincidence spectrometers have the potential to significantly enhance detection sensitivity for ultra-trace radionuclide measurements. The implementation of these spectrometers, however, is limited by the complexity of acquisition hardware, data processing and quantification. This work reports development of a novel radionuclide quantification software for γ-γ coincidence measurements. For any radionuclide, the software parses the Evaluated Nuclear Structure Data File (ENSDF) database, recursively simulating all possible γ-γ coincidence signatures and their respective emission and detection probabilities. Implemented using Python programming language, the software employs several strategies to boost overall computational performance. Since coincidence-based spectrometers are of notable interest in monitoring compliance for the Comprehensive Nuclear-Test-Ban Treaty (CTBT), the software’s execution was tested for 84 CTBT-relevant radionuclides. To date, the software has been experimentally validated for 15 radionuclides using the Advanced Radionuclide Gamma spectrOmeter (ARGO) at Pacific Northwest National Laboratory, USA (PNNL). Notably, the software can be operated in convergence mode, whereby coincidence detection efficiency’s convergence behavior can help avoid unreliable radionuclide activity estimates. With growing number of coincidence spectrometers worldwide, this paper aims to assist the radiation metrology community in developing similar software for their system.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

In-beam γ-ray spectroscopy of 37–42 P

The level schemes of the neutron-rich 37-42 P isotopes are investigated via in-beam gamma-ray spectroscopy following the fragmentation of a 45 Cl projectile beam at intermediate beam energies. Information on gamma-gamma coincidence relationships complemented by comparisons to shell-model calculations in the sd-pf model space were used to construct excitation level schemes for these neutron-rich nuclei. For the odd-mass 37,39 P isotopes, a level scheme is presented that appears essentially complete at low energies and exhausts the states predicted by the SDPF-MU shell-model Hamiltonian. In conclusion, simple Nilsson configurations are proposed for the low-lying excited states of 38,39,40,41 P from an analysis of the E2 transition matrix elements and moments calculated within the shell model.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

A Preliminary Investigation for the Use of Digital Gamma-Gamma Coincidence Spectrometry to Determine 239 Pu

Gamma-ray spectrometry is one of the most effective ways to determine the activity of 239 Pu, depending on activity levels. However, often high backgrounds in complex spectra with low amounts of 239 Pu can increase detection limits. The effectiveness of the use of gamma-gamma spectrometry in the characterization of 239 Pu was studied for the first time. Using the XIA Pixie-16 digital pulse processor, the gamma-gamma system was studied to establish unshielded background radiation, source to detector distances, Poisson statistics and gating of several gamma-rays from 239 Pu. The results clearly show that the distance between gamma ray spectrometers has a much bigger effort in counting statistics for the gamma-gamma coincidence detectors than a single detector. In addition, measurements demonstrated the background radiation to be virtually negligible, meaning gammagamma spectroscopy can still be very effective without requiring the usual lead shielding. Other measurements were taken to assure Poisson statistics were attained in the digital system. Preliminary measurements revealed 3 orders of magnitude background reduction for the measurement of 239 Pu using gated gamma-rays.

61 RADIATION PROTECTION AND DOSIMETRY↗