Scintillation characteristics of heavily doped CsI:Tl,IO3 crystals

Abstract

The effect of IO3- ions on spectrometric characteristic of CsI:Tl crystal has been considered. It has been shown that co-doping of CsI:Tl crystal by IO3- anions permits to obtain clear ingots with increased thallium concentration up to CTl ~ 0,9 mole % in which the concentration quenching of photo- or radioluminescence do not observed. It has been shown that the decay of solid solution in CsI:Tl,IO3 crystals is not observed, at least up to CTl ~ 0.5 mole %, as evidenced by a good energy resolution (R = 6.3%) of samples with the specified Tl concentration and this also evidenced by a larger segregation coefficient of thallium in CsI:Tl,IO3 crystals (k=0,24 contrary to k=0,19 in CsI:Tl). An explanation of thallium solid solution stability in CsI matrix has been proposed which based on experimental fact of Tl+⋯ IO3- complex formation. Compensation of elastic stresses of opposite sign due to complex formation results in preventing of nucleation for solid solution decay