Energy calibration of CsI(Tl) crystal for quenching factor measurement in dark matter search

It is important to measure the quenching factor of recoiled nuclei of detector for direct detection of WIMP. Energy calibration of CsI(Tl) crystal detector for measuring quenching factor of recoiled nuclei induced by incident neutron beam has been done with low-energy X-ray sources such as 109 Cd and 133 Ba and the linearity of energy response of experimental system is obtained. The equivalent energy deposited in CsI(Tl) crystal of a single photoelectron of PMT has been measured. The time of integration of current signals is optimized for different X-ray source energys.