Growth of a New, Fast Scintillator Crystal for Nuclear Experiments

70631 Rare earth orthophosphate crystals could satisfy the requirements for improved scintillators needed for nuclear physics experiments. These requirements include fast decay time (approximately 30 nsec with no slow component), greater light output compared to current materials, a radiation length less than 2 cm, and the ability to be grown in a large size (> 20 radiation lengths). All these requirements could be met at reasonable cost if a suitable solvent system and growth technique could be identified for cerium-doped gadolinium orthophosphate crystals. In this project, a new solvent system will be studied to identify the solution region from which cerium-doped gadolinium orthophosphate can be grown. The solution characteristics and phase relationships for this system will be investigated to determine the feasibility of growing large cerium-doped gadolinium orthophosphate crystals by top-seeded solution growth. In Phase I, various solution compositions will be studied to determine the solid phases present within the temperature range 1000-1200 degrees Celcius. The solids will be identified using x-ray powder diffraction, and the best solution composition will be utilized to grow cerium-doped crystals. The solution will then be characterized to identify conditions that can be utilized to grow crystals by applying the top-seeded solution growth technique. Commercial Applications and Other Benefits as described by the awardee: Cerium-doped gadolinium orthophosphate should have better characteristics than cerium doped gadolinium orthosilicate, which is a major scintillator crystal utilized in positron emission tomography. The growth technology for this orthophosphate crystal would allow the possibility of incorporating a series of rare earth analog crystals into many commercial laser systems.