Light yield maximization of triclinic La-GPS scintillator by optimizing La and Ce concentration

Tsubota, Yoichi   ; Waki, Takaaki*; Kaneko, Junichi* ; Higuchi, Mikio*; Ishibashi, Hiroyuki*

GdSiO:Ce (GPS) is a rare-earth oxide scintillator with large light yield (LY) exceed NaI:Tl and can be used under high temp. environment. The triclinic La-GPS, which substituted Gd site for La, also have LY close to NaI:Tl. Although several trials on growth of La-GPS were reported, systematic research on LY were not sufficiently carried out. In this report, the optimization of La and Ce concentration of La-GPS was conducted to maximize LY. Sintered (LaxGd1-x-yCey)SiO (x= 0.1, y= 0 - 0.16) and (x= 0 - 0.15, y= 0.025) were fixed on glass plates and mechanically polished to be approx. 100 micro-meter thick. For the evaluation of scintillation LY, alpha-particle response measurement using Am was performed. For the Ce= 2.5% samples, La-GPS with 5 - 6.7% of La showed the highest LY. LY was then decreased as the La increased. For the La=10% samples, light yield increased as Ce increased in the range of Ce=0.5-2.5% that corresponded with the increase of luminescent center of Ce. Decrease of LY due to concentration quenching was observed in the range of Ce4%.