Patent ID: 7347956

Claim:
A luminescent material for scintillators, comprising a single crystal of an Yb-containing mixed-crystal oxide which has a composition represented by either one of R 3 Al 5 O 12 , R 3 Ga 5 O 12 and Li 6 R(BO 3 ) 3 , wherein R is a mixture of Yb and either one of Gd and Lu, and said Yb as an element capable of forming an optically active state called CTS together with a neighboring negative ion adjacent thereto, wherein the molar ratio of either one of Gd and Lu to Yb in said R satisfies the conditions expressed by the following formulas: 1.04 x +1.02 y ≦1.03; x+y =1; 0<x<1; and 0<y<1, wherein x is a molar ratio of Yb, and y is a molar ratio of either one of Gd and Lu.