Tl-related radiation defects in CsI:Tl

Abstract Angular dependencies of the EPR spectra detected via the magnetic circular dichroism of the optical absorption (MCDA-EPR) observed in the MCDA bands at 355, 411, 425, 442, 465, 536, and 815 nm of γ- or X-irradiated CsI:Tl crystals have been investigated. The MCDA-EPR spectrum at B || [1 0 0] consists of two quartets of intense lines. The spectrum could be satisfactorily explained taking into account hyperfine (hf) interactions of unpaired electron with S= 1 2 with three Tl nuclei I ( 205 Tl , 203 Tl )= 1 2 . Therefore we propose as a model a Tl-trimer centre. The hf interactions along a [1 0 0] direction with two equivalent Tl and one single Tl were observed. As a centre model we p…