Improvement of lifetime of long lasting phosphor using quantum beams

To, Kentaro  ; Sakasai, Kaoru  ; Nakamura, Tatsuya  ; Soyama, Kazuhiko  ; Nagata, Shinji*; Tsuchiya, Bun*; Shikama, Tatsuo*

Lon-lasting phosphor (LLP) emits photons for a long period after the cessation of irradiation, without requiring any external excitation. This persistent luminescence after the cessation of irradiation is called as a long-lasting emission. Here, the decay time of the long-lasting emission mainly depends on the release rate of electrons in electron trap center, and this rate in turn depends on the energy level of the trap center in the host material. This study examines the properties of long-lasting emission under some kinds of radiation which cause a change of the structure in the host materials by its strong nuclear effects. The decay time of the long-lasting emission is different for different irradiation fluence under proton irradiation, and the emission with fluences of 6.8 10 p/m is strongest in our conditions. The change of the decay time is also observed under fast neutron irradiation.