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Measurement of the Antineutrino Spectrum from 235U Fission at HFIR with PROSPECT



Hans Pieter Mumm, Denis E. Bergeron, Mark Tyra, Svetlana Nour, Jerome LaRosa


This Letter reports the first measurement of the 235U e energy spectrum by PROSPECT, the Precision Reactor Oscillation and Spectrum experiment, operating 7.9 m from the 85MWth highly-enriched uranium (HEU) High Flux Isotope Reactor. With a surface-based, segmented detector, PROSPECT has observed 31678304 (stat.) e-induced inverse beta decays (IBD), the largest sample from HEU fission to date, 99% of which are attributed to 235U. Despite broad agreement, comparison of the Huber 235U model to the measured spectrum produces a 2=ndf = 51:4=31, driven primarily by deviations in two localized energy regions. The measured 235U spectrum shape is consistent with a deviation relative to prediction equal in size to that observed at low-enriched uranium power reactors in the e energy region of 5-7 MeV.
Physics Review Letters


antineutrino, 235U spectrum, neutrino-mixing, neutrino detector


, H. , , D. , Tyra, M. , Nour, S. and LaRosa, J. (2019), Measurement of the Antineutrino Spectrum from 235U Fission at HFIR with PROSPECT, Physics Review Letters, [online],, (Accessed June 22, 2024)


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Created June 28, 2019, Updated May 3, 2021