DANG and the Background Characterisation of HFIR for PROSPECT

This work is a detailed report on the composition, operation, and findings of DANG, constructed to characterize the reactor-related radiation flux at ORNL’s HFIR in preparation for the future short baseline neutrino experiment, PROSPECT. The PROSPECT experiment aims to provide a precise measurement of the antineutrino flux and energy spectrum by taking multiple measurements 7-12 m from the core with a highly segmented 6Li-doped liquid scintillator detector. These precise measurements will help resolve anomalies observed in reactor-based short baseline experiments’ data. Low background rates inside the PROSPECT detector are critical for extracting the needed antineutrino signal, as antineutrinos have a small interaction cross-section. PROSPECT’s close proximity to the reactor core makes this is particularly challenging as the reactor produces large amounts of radiation. Additionally a description of the development and instrumentation used to compose DANG, highlighting its unique design benefits and it’s future opportunities with PROSPECT and reactor studies, is given. Different methods used to test and characterise the 17 detectors attached to the array are presented, providing insight into potential effects and challenges one can encounter when building a multi-type detector array. Furthermore, data collected with DANG has been used to identify potential sources of background radiation creating fluctuations in radiation fields throughout the experimental hall. This work goes on to outline the cause of these sources, discusses their strength and concludes how best to mitigate them. This study also provides information about the spatial and temporal fluctuations in the experimental hall’s radiation field PROSPECT will occupy, as well as provide feedback on shielding designs within the hall to further reduce background radiation.