Testing feasibility of SrI2(Eu) scintillation detector for low-energy neutrino detection

Abstract: The possibility to use the SrI2(Eu) scintillator for detection of tritium neutrino with energy below 20 keV is suggested. SrI2(Eu) scintillator has a record light yield up to 120 photons/keV that in combination with high photon detection efficiency photodetectors would enable the detection threshold below 1 keV. The compact modular setup of SrI2(Eu) scintillation detectors to register sub-keV energy deposition from neutrinos interactions is considered. Each individual detector module comprises four small scintillators with attached SiPM arrays packed together in a light-tight plastic case. The main drawback of SiPM, the high dark current rate (DCR), which is exponentially dependent on temperature, can be suppressed at negative operating temperatures. The experimental tests of SiPMs were performed over a wide temperature range from +20°C to -65°C,that show the DRC reduction for about three orders. To further suppress the effect of DCR, a time coincidences of the signals in each detector module were implemented. The light collection of SrI2(Eu) scintillators with SiPM readout was studied using several γ-ray sources. The optimal operating conditions were examined to provide a minimum energy detection threshold. The normalized light collection achieves 26.3 photoelectron/keV in all range of measured energies. The performed tests with low energy γ-ray sources confirmed that constructed SrI2(Eu) modules are suitable for high-resolution X- and γ-rays spectroscopy.