Complete β -decay pattern for the high-priority decay-heat isotopes I137 and Xe137 determined using total absorption spectroscopy
| العنوان: | Complete β -decay pattern for the high-priority decay-heat isotopes I137 and Xe137 determined using total absorption spectroscopy |
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| المؤلفون: | K. P. Rykaczewski, A. V. Ramayya, Carl J Gross, Robert Grzywacz, J. H. Hamilton, David Miller, Bertis Rasco, M. Karny, S. Padgett, D. W. Stracener, K. Miernik, A. Fijałkowska, M. Madurga, K.C. Goetz, E. F. Zganjar, E. H. Spejewski, J. C. Blackmon, C. U. Jost, J.W. Johnson, Marzena Wolinska-Cichocka, S. V. Paulauskas, N. T. Brewer |
| المصدر: | Physical Review C. 95 |
| بيانات النشر: | American Physical Society (APS), 2017. |
| سنة النشر: | 2017 |
| مصطلحات موضوعية: | Physics, Total absorption spectroscopy, 010308 nuclear & particles physics, Neutron emission, Branching fraction, 01 natural sciences, Nuclear magnetic resonance, 0103 physical sciences, Neutron, Absorption (logic), Atomic physics, Nuclear Experiment, 010306 general physics, Ground state, Energy (signal processing), Intensity (heat transfer) |
| الوصف: | Background: An assessment done under the auspices of the Nuclear Energy Agency in 2007 suggested that the $\ensuremath{\beta}$ decays of abundant fission products in nuclear reactors may be incomplete. Many of the nuclei are potentially affected by the so called pandemonium effect and their $\ensuremath{\beta}\text{\ensuremath{-}}\ensuremath{\gamma}$ decay heat should be restudied using the total absorption technique. The fission products $^{137}\mathrm{I}$ and $^{137}\mathrm{Xe}$ were assigned highest priority for restudy due to their large cumulative fission branching fractions. In addition, measuring $\ensuremath{\beta}$-delayed neutron emission probabilities is challenging and any new technique for measuring the $\ensuremath{\beta}$-neutron spectrum and the $\ensuremath{\beta}$-delayed neutron emission probabilities is an important addition to nuclear physics experimental techniques.Purpose: To obtain the complete $\ensuremath{\beta}$-decay pattern of $^{137}\mathrm{I}$ and $^{137}\mathrm{Xe}$ and determine their consequences for reactor decay heat and ${\overline{\ensuremath{\nu}}}_{e}$ emission. Complete $\ensuremath{\beta}$-decay feeding includes ground state to ground state $\ensuremath{\beta}$ feeding with no associated $\ensuremath{\gamma}$ rays, ground state to excited states $\ensuremath{\beta}$ transitions followed by $\ensuremath{\gamma}$ transitions to the daughter nucleus ground state, and $\ensuremath{\beta}$-delayed neutron emission from the daughter nucleus in the case of $^{137}\mathrm{I}$.Method: We measured the complete $\ensuremath{\beta}$-decay intensities of $^{137}\mathrm{I}$ and $^{137}\mathrm{Xe}$ with the Modular Total Absorption Spectrometer at Oak Ridge National Laboratory. We describe a technique for measuring the $\ensuremath{\beta}$-delayed neutron energy spectrum, which also provides a measurement of the $\ensuremath{\beta}$-neutron branching ratio, ${P}_{n}$.Results: We validate the current Evaluated Nuclear Structure Data File (ENSDF) evaluation of $^{137}\mathrm{Xe}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$ decay. We find that major changes to the current ENSDF assessment of $^{137}\mathrm{I}\ensuremath{\beta}$-decay intensity are required. The average $\ensuremath{\gamma}$ energy per $\ensuremath{\beta}$ decay for $^{137}\mathrm{I}\ensuremath{\beta}$ decay ($\ensuremath{\gamma}$ decay heat) increases by 19%, from 1050--1250 keV, which increases the average $\ensuremath{\gamma}$ energy per $^{235}\mathrm{U}$ fission by $0.11%$. We measure a $\ensuremath{\beta}$-delayed neutron branching fraction for $^{137}\mathrm{I}\ensuremath{\beta}$ decay of $7.9\ifmmode\pm\else\textpm\fi{}0.2(\mathrm{fit})\ifmmode\pm\else\textpm\fi{}0.4(\mathrm{sys})%$ and we provide a $\ensuremath{\beta}$-neutron energy spectrum.Conclusions: The Modular Total Absorption Spectrometer measurements of $^{137}\mathrm{I}$ and $^{137}\mathrm{Xe}$ demonstrate the importance of revisiting and remeasuring complex $\ensuremath{\beta}$-decaying fission products with total absorption spectroscopy. We demonstrate the ability of the Modular Total Absorption Spectrometer to measure $\ensuremath{\beta}$-delayed neutron energy spectra. |
| تدمد: | 2469-9993 2469-9985 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_________::9f8a05672166f73a8da02b8b0f6d429e https://doi.org/10.1103/physrevc.95.054328 |
| حقوق: | OPEN |
| رقم الأكسشن: | edsair.doi...........9f8a05672166f73a8da02b8b0f6d429e |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 24699993 24699985 |
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