Study of the radiation hardness of the pure CsI crystals

Abstract This study was initiated by the Belle detector upgrade plan including the replacement of the CsI(Tl) crystals in the endcaps by the pure CsI. Within this work five samples of pure CsI crystals were irradiated by the beam of 0.6 MeV γ -quanta. The absorbed dose accumulated in several runs reached 55 krad for two samples and 13 krad for three others. Four of these samples were found to satisfy the super B-factory conditions. The light output reduction for them does not exceed 15% at 13 krad of absorbed dose. One sample had poor radiation resistance.