New Techniques for Handling Hygroscopic Scintillator Crystals and Detector Construction.

摘要

The purpose of the research was to determine if hygroscopic scintillation crystals such as NaI(T1) and LiI(Eu) could be handled and packaged without resort to dry boxes by using common laboratory materials and facilities. Several common liquids were examined to find those which would chemically dissolve the crystal hydrate and those which had no effect on the crystal. Pairs of liquids were examined to see if one of the pair would clean the crystal and the other remove the washing solution without effect on the crystal and neither liquid subsequently hydrate the crystal. Suitable liquids were found which wash and clean NaI(T1) leaving a glassy-clear crystal. Whole crystals and crystal fragments were chemically cleaned this way and incorporated into scintillation crystal detectors using encapsulating gels. The whole crystal detectors performed well.Detectors of crystal fragments had poorer stopping power and their ability to resolve gamma ray spectra was questionable. The resistance of the fragmented crystal detectors to thermal and mechanical shock was assessed and found to be superior to conventional whole crystal detectors. It was not possible to find suitably dry laboratory liquids to clean and store LiI(Eu) crystals. All candidate liquids, even after several drying procedures, caused some hydration of the crystal. Despite the hydration, LiI(Eu) detectors, which seemed to performed as well or better than standard commercial detectors, were produced.