An improved short-baseline neutrino oscillation search and energy spectrum measurement with the PROSPECT experiment at HFIR has been published this week (3 February 2021) in Physical Review D and highlighted as an Editor’s Suggestion. Strong ORNL/UTK participation continues in the experiment. In particular two graduate students, Jeremy Lu and Diego Vargas Venegas played a very important role in the data analysis for this paper.
PROSPECT is the first short-baseline reactor neutrino experiment in the United States since the Savannah River experiments of Reines et al. This first of its kind short-distance detection device was used at the High Flux Isotope Reactor at Oak Ridge National Laboratory. PROSPECT was designed to address the two most prominent interpretations of an array of anomalous results facing neutrino physics. The specific physics goals are 1) performing a definitive search for the existence of eV-scale sterile neutrinos in the region preferred by global flux data and 2) providing a precise measurement of the antineutrino energy spectrum produced by a highly-enriched 235U reactor. In addition to these scientific goals, PROSPECT has also made notable technical progress by successfully operating a neutrino detector at the Earth’s surface capable of achieving a signal-to background ratio of better than 1:1.
In this paper the PROSPECT I results from the first data campaign are reported. By comparing the new measurements to the beta-conversion prediction for 235U, PROSPECT verified its general accuracy, while providing first indications that 235U is not solely responsible for deviations of Daya Bay’s Low Enriched Uranium reactor measurement from predictions at high energies.
