Response of NAI (Tl) to X-Rays and Low Energy Gamm Rays

A thorough investigation of the response of NaI(Tl) in the region below 50 kev was made using a continuous distribution of X-rays from a tungsten target as well as monoenergetic gamma rays from radioactive sources. The results of this investigation agree well with those of Engelkemeir.1 The investigation also showed that below 20 kev NaI(Tl) is sensitive to surface treatment. Above 20 kev the response is independent of surface treatment as long as the surface is free of moisture. An electron response curve is shown which, when used with the decay scheme of the excited iodine atom, predicts the observed nonlinear response NaI(Tl) to low energy X-and)x-rays.