| abstract |
A polycrystalline scintillator for detecting soft X-rays, which comprises Ce as a light-emitting element and at least Y, Gd, Al, Ga and O, and has a garnet crystal structure, and a composition represented by the general formula of (Y 1-x-z Gd x Ce z ) 3+a (Al 1-u Ga u ) 5-a O 12 , wherein 0≦a≦0.1, 0.15≦x≦0.3, 0.002≦z≦0.015, and 0.35≦u≦0.55, with 0.05-1 ppm by mass of Fe and 0.5-10 ppm by mass of Si by outer percentage, a ratio μ 50 /μ 100 of 3 or more, wherein μ 50 is an absorption coefficient of X-rays at 50 keV, and μ 100 is an absorption coefficient of X-rays at 100 keV, and afterglow of 800 ppm or less after 3 ms from the termination of X-ray irradiation. |