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Joint Measurement of the 235U Antineutrino Spectrum with PROSPECT and STEREO



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


The PROSPECT and STEREO collaborations present a combined measurement of the pure 235U antineutrino spectrum, with site specific corrections and effects dependent on the separate detectors removed. The spectral measurements of the two highest-precision experiments at research reactors are found to be compatible with χ2/ndf = 24.1/21, allowing a joint unfolding of the prompt energy measurements into antineutrino energy. This antineutrino energy spectrum is provided to the community, and an excess of events is found in the 5-6 MeV region. When a gaussian bump is fitted to the excess, the data-model χ2 value is reduced by 12.0 while removing 3 degrees of freedom, corresponding to a 2.4σ significance.
Physical Review Letters


reactor antineutrino spectrum, 235U neutrino spectrum, fission daughter neutrinos


Mumm, H. , Bergeron, D. , Tyra, M. , LaRosa, J. , Nour, S. , COLLABORATION, P. and collaboration, S. (2022), Joint Measurement of the 235U Antineutrino Spectrum with PROSPECT and STEREO, Physical Review Letters, [online],, (Accessed July 15, 2024)


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Created February 22, 2022, Updated November 29, 2022