The radioactive source calibration system of the PROSPECT reactor antineutrino detector

Abstract The Precision Reactor Oscillation and Spectrum ( PROSPECT) Experiment is a reactor neutrino experiment designedto search for sterile neutrinoswith a mass on the order of 1 eV/c measure the spectrum of electron antineutrinos from a highly-enriched 235U nuclear reactor. The PROSPECTdetector consists of an 11 by 14 array of optical segments in 6Li-loaded liquid scintillator at the High Flux Isotope Reactorin Oak Ridge National Laboratory. Antineutrino events are identified via inverse beta decayand read out by photomultipliertubes located at the ends of each segment. The detector response is characterized using a radioactive sourcecalibration system. This paper describes the design, operation, and performance of the PROSPECTsource calibration system.