Scintillation crystals having reduced afterglow and method of making the same

摘要

Methods of making a scintillation crystal having reduced afterglow include preparing a crystal melt according to the Czochralsky technique and doping the melt with an element or a compound which reduces afterglow without significantly reducing the luminescence light output of the crystal grown in the melt. Experiments have shown that doping the melt with any one of calcium, cobalt, germanium, niobium, sodium, and chromium significantly reduces afterglow without unduly reducing the luminescence light output of the crystal. The presently preferred dopant is cobalt, which is added to the melt in concentrations of approximately 10ppm to 50ppm. Crystals made according to the method of the invention exhibit significantly less afterglow than crystals made from the same raw materials without doping. By choice of the proper concentration of dopant, the light output of the crystal during luminescence is not adversely affected.