First-forbidden transitions in the reactor anomaly
Hayen, L., Kostensalo, J., Severijns, N., & Suhonen, J. (2019). First-forbidden transitions in the reactor anomaly. Physical Review C, 100(5), Article 054323. https://doi.org/10.1103/PhysRevC.100.054323
Published inPhysical Review C
© American Physical Society, 2019
We describe here microscopic calculations performed on the dominant forbidden transitions in reactor antineutrino spectra above 4 MeV using the nuclear shell model. By taking into account Coulomb corrections in the most complete way, we calculate the shape factor with the highest fidelity and show strong deviations from allowed approximations and previously published results. Despite small differences in the ab initio electron cumulative spectra, large differences on the order of several percent are found in the antineutrino spectra. Based on the behavior of the numerically calculated shape factors we propose a parametrization of forbidden spectra. Using Monte Carlo techniques we derive an estimated spectral correction and uncertainty due to forbidden transitions. We establish the dominance and importance of forbidden transitions in both the reactor anomaly and spectral shoulder analysis with their respective uncertainties. Based on these results, we conclude that a correct treatment of forbidden transitions is indispensable in both the normalization anomaly and spectral shoulder. ...
PublisherAmerican Physical Society
Publication in research information system
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Related funder(s)Academy of Finland
Funding program(s)Academy Project, AoF
Additional information about fundingThis work has been partly funded by the Belgian Federal Science Policy Office, under Contract No. IUAP EP/12-c, and the Fund for Scientific Research Flanders (FWO). This work has been partially supported by the Academy of Finland under Academy Project No. 318043. J.K. acknowledges the financial support from the Jenny and Antti Wihuri Foundation.
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