Calibration of the highly segmented SoLid antineutrino detector

TL;DR

The paper discusses calibration methods for the highly segmented SoLid antineutrino detector, which is designed to study reactor antineutrino anomalies and energy spectra, addressing calibration challenges posed by its fine granularity.

Contribution

It introduces novel calibration techniques tailored for the segmented SoLid detector and presents calibration results demonstrating their effectiveness.

Findings

Successful calibration of the detector response.

Improved energy scale and neutron detection efficiency.

Enhanced background discrimination capabilities.

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.