Inorganic scintillator
The inorganic scintillator of the invention is an inorganic scintillator capable of producing scintillation by radiation, which is a crystal comprising a metal oxide containing Lu, Gd, Ce and Si and belonging to space group C2/c monoclinic crystals, and which simultaneously satisfies the conditions specified by the following inequalities (1) and (2). { A Lu /( A Lu +A Gd )}<0.50 (1) { A Ce /( A Lu +A Gd )}≧0.002 (2) wherein A Lu represents the number of Lu atoms in the crystal, A Gd represents the number of Gd atoms in the crystal, and A Ce represents the number of Ce atoms in the crystal.
1. An inorganic scintillator capable of producing scintillation by radiation, which is a crystal comprising a metal oxide containing Lu, Gd, Ce and Si and belonging to space group C 2 /c monoclinic crystals, and
by simultaneously satisfying the conditions specified by the following inequalities (1) and (2),
by outputting a fluorescent pulse, upon incidence of a radiation pulse to said inorganic scintillator, which is composed of a first fluorescent component exhibiting a fluorescent lifetime τ 1 and a second fluorescent component exhibiting a fluorescent lifetime τ 2 which is longer than the fluorescent lifetime τ 1 , and
by simultaneously satisfying the conditions specified by the following inequalities (1) and (4), wherein
{ A Lu /( A Lu +A Gd )}<0.50 (1)
0.02 ≧{A Ce /( A Lu +A Gd )}≧0.002 (2)
(τ2/τ1)≦8 (4)
wherein A Lu represents the number of Lu atoms in said crystal, A Gd represents the number of Gd atoms in said crystal, and A Ce represents the number of Ce atoms in said crystal.
2. An inorganic scintillator according to claim 1 which satisfies the condition specified by the following inequality (3)
0.005 ≦{A Ce /( A Lu +A Gd )}≦0.02 (3).
3. An inorganic scintillator according to claim 1 which satisfies the condition specified by the following inequality (5)
(τ2/τ1)≦4 (5).
4. An inorganic scintillator according to claim 1 which satisfies the condition specified by the following inequality (6)
{( S 1+ S 2)/ S}≧ 0.90 (6)
wherein S is the time integrated value of the intensity of said fluorescent pulse as a whole, S 1 is the time integrated value of said first fluorescent component intensity and S 2 is the time integrated value of said second fluorescent component intensity.
5. An inorganic scintillator according to claim 4 which satisfies the condition specified by the following inequality (7)
0.10≦{ S 1/( S 1+ S 2)}≦0.90 (7).
6. An inorganic scintillator according to claim 1 , which is a single crystal.
7. An inorganic scintillator according to claim 1 , wherein 0.15≦{A Lu /(A Lu +A Gd )}<0.50.