The Luminescence in CsI : Tl

The luminescence in pure CsI and CsI : Tl crystals containing various concentrations of Tl have been measured upon excitation by beta rays over the temperature range from -180°C to +20°C. The emission spectra in pure CsI at low temperatures have two peaks whose temperature dependence are different each other. In the case of CsI : Tl, the temperature dependence of the luminescence near 400 mµ is quite different from that of longer wavelength luminescence. In the longer wavelength region around 500 mµ, several glow peaks are observed from the samples of higher concentration of Tl. The process of luminescence in CsI : Tl are roughly explained by using the self trapped hole model.