Respond to nuclear recoil of the undoped CsI at temperatures of 77K

We present a study of the scintillation response of cesium iodide (CsI) to low-energy nuclear recoils, motivated by its application in coherent elastic neutrino–nucleus scattering (CEvNS) and dark matter detection. A dedicated cryogenic setup was developed to operate the CsI detector at temperatures at 77 K, with optimized optical coupling and infrared shielding to minimize background and thermal noise. Nuclear recoils were induced by a neutron beam, and their energies were reconstructed using time-of-flight (ToF) and scattering-angle measurements. We will report the experimental configuration and results on the CsI light yield and quenching factor under cryogenic conditions. These measurements provide key input for modeling the response of future CsI-based CEvNS detectors and highlight the promise of cryogenic CsI as a sensitive target for rare-event searches.