Evaluation of properties of YAG (Ce) ceramic crystal scintillators

We measured basic properties of three ceramic Y/sub 3/Al/sub 5/O/sub 12/ (YAG) scintillators doped with Ce to a concentration of 0.5, 0.05, and 0.005 mol%, in comparison with a single YAG scintillator unknown amount of Ce doping. First, transparency and emission spectrum were investigated. We confirmed that the transparency of the ceramics is comparable to that of the single one (/spl sim/80%) in wavelengths in longer than /spl sim/500 nm. The ceramics did not show an indication of lattice defects which is present in the single YAG. Then the response to /spl gamma/-rays was studied using a phototube as a scintillation light detector. The 0.5 mol% exhibited the highest light yield (/spl sim/40% of CsI), with an energy resolution of about 7.2% at /sup 137/Cs 662 keV photoabsorption peak. The optimum Ce concentration for a /spl sim/2 mm thick ceramic YAG was determined to be /spl sim/0.1 mol%. Using the delayed coincidence method, the principal time constant of the ceramic YAGs was measured as /spl sim/80 ns. By irradiating 5.49 MeV /spl alpha/-particles, the /spl alpha/-ray to /spl gamma/-ray light yield ratio of the ceramic YAGs was found to depend negatively on the amount of Ce; namely, 0.28, 0.20, and 0.13 in the decreasing order of the concentration. The 200-1000 keV intrinsic background of the 0.5 mol% ceramic was /spl sim/10/sup -5/ counts/s/cm/sup 3/, indicating that it is not significantly contaminated by radioactive impurities.