Neutron-gamma discrimination of CsI(Na) crystals for dark matter searches
arXiv:1102.2727 · doi:10.1016/j.nima.2011.03.062
Abstract
The luminescent properties of CsI(Na) crystals are studied in this report. By using a TDS3054C oscilloscope with a sampling frequency of 5 GS/s, we find out that nuclear recoil signals are dominated by very fast light pulse with a decay time of ~20 ns, while γ-ray signals have a decay time of ~600 ns. The wavelength of nuclear recoil and γ-ray signals are also different. The study of n/γ separation shows that the rejection factor can reach an order of 10-7 with signal efficiency more than 80% at an equivalent electron recoil energy of 20 keV or more. Such a property makes CsI(Na) an ideal candidate for dark matter searches.
11 pages, 15 figures