Calibration of the highly segmented SoLid antineutrino detector

Abstract

SoLid is a short baseline neutrino experiment, which is currently operating a 1.6 tons detector at the SCK$\bullet$CEN BR2 research reactor in Belgium. SoLid will address the study of the so called Reactor Antineutrino Anomaly (RAA), whose origin could be the existence of a light sterile neutrino state with a mass around the eV scale. In addition, it will perform a new measurement of the antineutrino energy spectrum produced by the $^{235}$U isotope, which will help in the understanding of the 5-MeV distortion observed in previous reactor antineutrino experiments. SoLid leverages a novel technology, combining PVT cubes of 5$\times$5$\times$5 cm$^{3}$ dimensions and $^{6}$LiF:ZnS(Ag) screens of $\sim$250 $\mu$m thickness. To detect antineutrino interactions, signals are readout by a network of wavelength shifting fibers and SiPMs. The fine granularity (12800 cells) provides powerful tools to distinguish signal from background, but presents a challenge in ensuring homogeneous detector response and calibrating the energy scale and neutron detection efficiency. In this contribution the methods that have been developed for the calibration of such a segmented detector will be described. In addition, the calibration results are presented.