Purification and growth of PbI/sub 2/ crystals: dependence of the radiation response on the PbI/sub 2/ crystal purity

Lead iodide starting materials have been purified by a multipass zone refining process. The effectiveness of the purification method on the material purity was determined by neutron activation analysis after three different purification passes numbers. A significant decrease of the impurities concentration was observed in function of the passes number. The purest material of the zone refined ingots, middle section, was used for crystal growth by Bridgman method. The results of the dark leakage current, the resistivity, and the response of the alpha and gamma radiations were strongly dependent on the purity of the crystal.