Improvement of ceramic YAG(Ce) scintillators to (YGd)3Al5O12(Ce) for gamma-ray detectors

Based on our successful development of ceramic Y3Al5O12(Ce) scintillators, we fabricated two samples of (YGd)3Al5O12(Ce) scintillator, to achieve higher stopping power to gamma-rays. They are both activated with Ce to a 0.5 mol% concentration, but differ in sintering conditions. We investigated their optical properties and gamma-ray responses. One of them showed a poor (∼1%) optical transparency at 550 nm, while the other had a much improved (∼20%) transmission. They both showed a dominant decay constant of ∼90 ns, when irradiated with gamma-rays. The more transparent one exhibited light yield which is ∼30% of that of ceramic YAG(Ce), and ∼14% (FWHM) energy resolution at 662 keV when coupled with a phototube. When coupled with an avalanche photo diode, it exhibited ∼8% energy resolution at the same energy. The stopping power of the new ceramics was confirmed to be five times as high as that of YAG(Ce) at ∼660 keV, by counting detected photo-absorption events.