PROSPECT-II detector design and external calibration scheme

PROSPECT, the Precision Reactor Oscillation and SPECTrum Experiment, operates at very short baselines from the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory to make precision flux and energy spectral measurements of reactor antineutrinos. One of the goals of PROSPECT is to search for a signature of antineutrinos changing or oscillating into a sterile type of neutrino. In its first phase, PROSPECT-I produced some of the strongest limits on eV-scale sterile neutrinos, made a precision measurement of the reactor antineutrino spectrum from U-235, and demonstrated the observation of reactor antineutrinos in an aboveground detector with good energy resolution and well-controlled backgrounds. The PROSPECT collaboration is now preparing an upgraded detector, PROSPECT-II, to probe yet unexplored parameter space for sterile neutrinos and contribute to a full resolution of the Reactor Antineutrino Anomaly, a long-standing puzzle in neutrino physics. This talk will cover the detector improvements and provide details of a new external calibration scheme.