Growth and Characterization of SrI2:Eu Crystals Fabricated by the Czochralski Method

Abstract

This paper presents the Czochralski growth of SrI2:Eu scintillation crystals. SrI2:Eu is one among the brightest recently discovered scintillators with an excellent energy resolution for spectroscopic identification of radioactive isotopes. The Czochralski crystal growth method is optimal from the point of scaling up of crystal production with minimal investment into upgrade of crystal growth equipment. In this paper, SrI2:Eu crystals with the diameter of up to 50 mm were produced by the developed process based on the Czochralski method. The crystals are prone to cracking, and thermal fields in the crystallizer still should be optimized. Nevertheless, the scintillation parameters of detectors cut from the grown crystals are similar to that in detectors fabricated by the conventional Bridgman–Stockbarger technology. The Eu2+ activator concentration across the crystals is uniform within 5%, as well as the energy resolution, which ranges within 3.6% ± 0.1% at 662 keV. Also, the decay times under X-rays and nonproportionality of scintillation light yield on excitation energy in the range of 31–1274 keV have been determined.