Solid scintillator, radiation detector, and radiation examination device
A solid scintillator in an embodiment includes a polycrystal body of an oxide having a garnet structure. In the solid scintillator, a linear transmittance at a wavelength of 680 nm is 10% or more. The oxide constituting the solid scintillator has a composition represented by, for Example, General formula: (Gd 1−α−β−γ Tb α Lu β Ce γ ) 3 (Al 1−x Ga x ) a O b , wherein 0<α≦0.55, 0<β≦0.55, 0.0001≦γ≦0.1, α+β+γ<1, 0<x<1, 4.8≦a≦5.2, 11.6≦b≦12.4.
1. A solid scintillator, comprising:
a polycrystal body of an oxide having a garnet structure, and a composition requested by a general formula:
(Gd 1−α−β−γ Tb α Lu β Ce 65 ) 3 (Al 1−x GA x ) a O b
where, α, β, and γ are numbers, which are atomic ratios, satisfying 0<α<0.55, 0<β≦0.55, 0.0001≦γ≦0.1, and α+β+γ<1,
x is a number, which is an atomic ratio, satisfying 0<x<1,
a is a number, which is an atomic ratio, satisfying 4.8≦a≦5.2, and
b is a number, which is an atomic ratio, satisfying 11.6≦b≦12.4,
wherein a linear transmittance at a wavelength of 680 nm is 10% or more.
2. The solid scintillator according to claim 1 ,
wherein the linear transmittance at the wavelength of 680 nm is 20% or more.
3. The solid scintillator according to claim 1 ,
wherein α satisfies 0.1≦α≦0.5, β satisfies 0.01≦β≦0.5, and x satisfies 0.01<x≦0.8.
4. The solid scintillator according to claim 1 ,
wherein the total amount of α, β, and γ satisfies α+β+γ≦0.9.
5. The solid scintillator according to claim 1 ,
wherein a content of barium is 400 mass ppm or less, including zero.
6. The solid scintillator according to claim 1 ,
wherein a content of fluorine is 300 mass ppm or less, including zero.
7. The solid scintillator according to claim 1 ,
wherein a ratio (I P /I G ) of a maximum peak intensity I P of a perovskite phase to a maximum peak intensity I G of a garnet phase by X-ray diffraction is 0.01 or less, including zero.
8. The solid scintillator according to claim 1 ,
wherein a maximum light emission peak when the solid scintillator is excited by an X-ray exists in a range of from 530 to 560 nm.
9. The solid scintillator according to claim 1 ,
wherein a decay time until an afterglow becomes 5% is 5 ms or less.
10. The solid scintillator according to claim 1 ,
wherein an average crystal grain diameter of the polycrystal body is in a range of from 2 to 50 μm.
11. The solid scintillator according to claim 1 ,
wherein a relative density of the polycrystal body is 99.5% or more.
12. The solid scintillator according to claim 1 ,
wherein a diffuse transmittance at a wavelength of 680 nm is 50% or more.
13. A radiation detector comprising the solid scintillator according to claim 1 .
14. A radiation examination device comprising the radiation detector according to claim 13 .