Reexamination of a 40Ca(n,α)37Ar cross section measurement from existing literature [version 2; peer review: 2 approved]

Background 37Ar, produced from the neutron activation of 40Ca in sub-surface rock and soil, is important for nuclear explosion monitoring. Most of the cross section measurements done for the 40Ca(n,α) 37 Ar reaction are in the fast neutron region. A thermal cross section measurement was attempted in...

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Main Authors: Derek Haas, Khiloni Shah
Format: Article
Language:English
Published: F1000 Research Ltd 2024-03-01
Series:Nuclear Science and Technology Open Research
Subjects:
Online Access:https://nstopenresearch.org/articles/1-21/v2
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author Derek Haas
Khiloni Shah
author_facet Derek Haas
Khiloni Shah
author_sort Derek Haas
collection DOAJ
description Background 37Ar, produced from the neutron activation of 40Ca in sub-surface rock and soil, is important for nuclear explosion monitoring. Most of the cross section measurements done for the 40Ca(n,α) 37 Ar reaction are in the fast neutron region. A thermal cross section measurement was attempted in 1989, with the assumption that the 4-8 MeV neutrons would be completely thermalized with 8-cm of water. Methods The experimental setup was modeled using Monte Carlo N-Particle code to see if the assumptions for the neutron distribution were accurate. A model of a 3.0 MeV deuteron source was used to recreate the neutron source from the experiment. Additional modeling was done using SCALE to compare the predictions of 37Ar yields when using the measured cross section from 1989 compared to current nuclear data models. Results Modeling showed the neutron distribution was closer to 10% thermal and 90% fast as opposed to entirely thermalized. The additional modeling showed how the overestimation of the thermal cross section would affect the predicted yield of 37Ar. Conclusions Based on the modeling results, the assumption that all the 4-8 MeV neutrons are thermalized with 8-cm of water is not accurate. The high fraction of fast neutrons interacting with the Ca will result in an overestimation of the thermal cross section.
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spelling doaj-art-c7169ca3dc264357ae950883e63bbe0b2025-08-20T01:58:52ZengF1000 Research LtdNuclear Science and Technology Open Research2755-967X2024-03-01110.12688/nuclscitechnolopenres.17446.218822Reexamination of a 40Ca(n,α)37Ar cross section measurement from existing literature [version 2; peer review: 2 approved]Derek Haas0https://orcid.org/0000-0003-2929-8974Khiloni Shah1https://orcid.org/0000-0002-8164-4216Nuclear and Radiation Engineering, The University of Texas at Austin, Austin, Texas, 78758, USANuclear and Radiation Engineering, The University of Texas at Austin, Austin, Texas, 78758, USABackground 37Ar, produced from the neutron activation of 40Ca in sub-surface rock and soil, is important for nuclear explosion monitoring. Most of the cross section measurements done for the 40Ca(n,α) 37 Ar reaction are in the fast neutron region. A thermal cross section measurement was attempted in 1989, with the assumption that the 4-8 MeV neutrons would be completely thermalized with 8-cm of water. Methods The experimental setup was modeled using Monte Carlo N-Particle code to see if the assumptions for the neutron distribution were accurate. A model of a 3.0 MeV deuteron source was used to recreate the neutron source from the experiment. Additional modeling was done using SCALE to compare the predictions of 37Ar yields when using the measured cross section from 1989 compared to current nuclear data models. Results Modeling showed the neutron distribution was closer to 10% thermal and 90% fast as opposed to entirely thermalized. The additional modeling showed how the overestimation of the thermal cross section would affect the predicted yield of 37Ar. Conclusions Based on the modeling results, the assumption that all the 4-8 MeV neutrons are thermalized with 8-cm of water is not accurate. The high fraction of fast neutrons interacting with the Ca will result in an overestimation of the thermal cross section.https://nstopenresearch.org/articles/1-21/v2Neutron cross section radioargon nuclear explosion monitoring 37Areng
spellingShingle Derek Haas
Khiloni Shah
Reexamination of a 40Ca(n,α)37Ar cross section measurement from existing literature [version 2; peer review: 2 approved]
Nuclear Science and Technology Open Research
Neutron cross section
radioargon
nuclear explosion monitoring
37Ar
eng
title Reexamination of a 40Ca(n,α)37Ar cross section measurement from existing literature [version 2; peer review: 2 approved]
title_full Reexamination of a 40Ca(n,α)37Ar cross section measurement from existing literature [version 2; peer review: 2 approved]
title_fullStr Reexamination of a 40Ca(n,α)37Ar cross section measurement from existing literature [version 2; peer review: 2 approved]
title_full_unstemmed Reexamination of a 40Ca(n,α)37Ar cross section measurement from existing literature [version 2; peer review: 2 approved]
title_short Reexamination of a 40Ca(n,α)37Ar cross section measurement from existing literature [version 2; peer review: 2 approved]
title_sort reexamination of a 40ca n α 37ar cross section measurement from existing literature version 2 peer review 2 approved
topic Neutron cross section
radioargon
nuclear explosion monitoring
37Ar
eng
url https://nstopenresearch.org/articles/1-21/v2
work_keys_str_mv AT derekhaas reexaminationofa40cana37arcrosssectionmeasurementfromexistingliteratureversion2peerreview2approved
AT khilonishah reexaminationofa40cana37arcrosssectionmeasurementfromexistingliteratureversion2peerreview2approved