Evaluation of properties of YAG (Ce) ceramic scintillators

We measured basic properties of three ceramic Y3Al5O12 (YAG) scintillators doped with Ce to a concentration of 0.5, 0.05, and 0.005 mol%, in comparison with a monocrystalline YAG scintillator with unknown amount of Ce doping. First, optical transparency and emission spectra were investigated. We confirmed that the transparency of the ceramics is comparable to that of the monocrystalline one (similar to 80%) in wavelengths longer than similar to 500 nm. The ceramics did not show an indication of lattice defects which is present in the monocrystalline YAG. Then the response to gamma-rays was studied using a phototube as a scintillation light detector. The 0.5 mol% sample exhibited the highest light yield (similar to 40% of CsI), with an energy resolution of about 7.2% at Cs-137 662 keV photoabsorption peak. The optimum Cc concentration for a similar to 2 mm thick ceramic YAG was determined to be similar to 0.1 mol%. Using the delayed coincidence method, the principal time constant of the ceramic YAGs was measured as similar to 80 ns. By irradiating 5.49 MeV alpha-particles, the alpha-ray to gamma-ray light yield ratio of the ceramic YAGs was found to depend negatively on the amount of Cc; namely, 0.28, 0.20, and 0.13 in the increasing order of the Ce concentration. The 200-1000 keV intrinsic background of the 0.5 mol% ceramic was similar to 10(-5) counts/s/cm(3), indicating that it is not significantly contaminated by radioactive impurities.