A1 Journal article (refereed)
Analysis of the total β-electron spectrum of 92Rb : Implications for the reactor flux anomalies (2022)
Ramalho, M., Suhonen, J., Kostensalo, J., Alcalá, G. A., Algora, A., Fallot, M., Porta, A., & Zakari-Issoufou, A.-A. (2022). Analysis of the total β-electron spectrum of 92Rb : Implications for the reactor flux anomalies. Physical Review C, 106(2), Article 024315. https://doi.org/10.1103/PhysRevC.106.024315
JYU authors or editors
Publication details
All authors or editors: Ramalho, M.; Suhonen, J.; Kostensalo, J.; Alcalá, G. A.; Algora, A.; Fallot, M.; Porta, A.; Zakari-Issoufou, A.-A.
Journal or series: Physical Review C
ISSN: 2469-9985
eISSN: 2469-9993
Publication year: 2022
Publication date: 16/08/2022
Volume: 106
Issue number: 2
Article number: 024315
Publisher: American Physical Society (APS)
Publication country: United States
Publication language: English
DOI: https://doi.org/10.1103/PhysRevC.106.024315
Publication open access: Not open
Publication channel open access:
Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/83703
Abstract
We present here a microscopic nuclear-structure calculation of a β-electron spectrum including all the β-decay branches of a high Q-value reactor fission product contributing significantly to the reactor antineutrino energy spectrum. We perform large-scale nuclear shell-model calculations of the total electron spectrum for the β− decay of 92Rb to states in 92Sr using a computer cluster. We exploit the β-branching data of a recent total absorption γ-ray spectroscopy (TAGS) measurement to determine the effective values of the weak axial-vector coupling, gA, and the weak axial charge, gA(γ5). By using the TAGS data we avoid the bias stemming from the pandemonium effect which is a systematic error biasing the usual β-decay measurements. We take fully into account all the involved allowed and forbidden β transitions, in particular the first-forbidden nonunique ones which have earlier been shown to be relevant in the context of the reactor-antineutrino flux anomaly and the unexplained spectral shoulder, the “bump,” the former one having been interpreted as one of the strongest evidence for the existence of sterile neutrinos. Here we are able to present quantitative evidence for the relevance of forbidden nonunique β− decays in a total β spectrum of a fission product, in this case 92Rb, which is one of the major contributors to the total reactor antineutrino spectral shape. We demonstrate that taking the forbidden spectral shapes fully into consideration leads for 92Rb to a 2.6%–4.6% reduction in the expected inverse β-decay rate at the reactor antineutrino telescopes. We also confirm by our calculation of a total β-electron spectrum that the forbidden transitions can contribute to the formation of the spectral bump in the reactor-antineutrino flux profile.
Keywords: nuclear physics; rubidium; beta radiation; neutrinos
Contributing organizations
Related projects
- Nuclear Theory for Fundamental Physics
- Suhonen, Jouni
- Research Council of Finland
Ministry reporting: Yes
VIRTA submission year: 2022
JUFO rating: 2