Speaker
Description
We present the development and comprehensive characterization of a large-volume cryogenic pure CsI detector system designed for coherent elastic neutrino-nucleus scattering (CEνNS) measurements and low-energy rare-event searches. The detector system employs two 3.3 kg high-purity CsI crystals operated at approximately 95 K with dual-ended 3-inch photomultiplier tube readout.
At cryogenic temperature, the detector achieves exceptional performance with light yields of 28.7±0.9 and 29.3±1.0 photoelectrons per keV electron-equivalent (PE/keVee) for the two crystals, corresponding to energy resolutions of 7.2% and 7.7% (FWHM) at 59.6 keV. The detector demonstrates excellent spatial uniformity along the 27 cm crystal length, indicating negligible bulk light attenuation. Long-term stability tests confirm consistent operation over one month with stable temperature control (95±2 K) and maintained PMT gain.
The intrinsic radioactivity of the crystals was evaluated using a multi-layer passive shielding system (5 cm lead + 10 cm HDPE). Analysis of 24-hour self-triggered data reveals exceptionally low contamination levels, with upper limits of 134Cs and 137Cs activities below 5 mBq/kg.
These results establish cryogenic pure CsI as a scalable and competitive technology for next-generation CEνNS experiments at spallation neutron sources and reactor neutrino facilities, as well as for direct dark matter searches requiring sub-keV detection thresholds.