Reactor neutrino physics potentials of cryogenic pure-CsI crystal

TL;DR

This paper demonstrates a record high scintillation light yield from a cryogenic pure-CsI crystal detector, enabling advanced neutrino detection and other applications due to enhanced light output at low temperatures.

Contribution

It reports the first stable cryogenic operation of a kg-scale pure-CsI detector with SiPM arrays, achieving a world-leading light yield for neutrino physics applications.

Findings

Achieved 30.1 photoelectrons/keV light yield at 77K

First stable operation of pure-CsI with SiPMs at cryogenic temperatures

Potential application in reactor neutrino detection

Abstract

This paper presents a world-leading scintillation light yield among inorganic crystals measured from a 0.5~kg pure-CsI detector operated at 77 Kelvin. Scintillation photons were detected by two 2-inch Hamamatsu SiPM arrays equipped with cryogenic front-end electronics. Benefiting the light yield enhancement of pure-CsI at low temperatures and the high photon detection efficiency of SiPM, a light yield of 30.1 photoelectrons per keV energy deposit was obtained for X-rays and $\gamma$-rays with energies from 5.9~keV to 59.6~keV. Instrumental and physical effects in the light yield measurement are carefully analyzed. This is the first stable cryogenic operation of kg-scale pure-CsI crystal readout by SiPM arrays at liquid nitrogen temperatures for several days. The world-leading light yield opens a door for the usage of pure-CsI crystal in several fields, particularly in detecting the coherent elastic neutrino-nucleus scattering of reactor neutrinos. The potential of using pure-CsI crystals in neutrino physics is discussed in the paper.