Development of an alpha particle spectrometer based on a GPS scintillator plate based for high-reliable dust monitor

Morishita, Yuki   ; Kaneko, Junichi* ; Izaki, Kenji ; Yajima, Tatsuo*; Matsuura, Mitsugu*

For detecting airborne contamination of Pu and Pu released by the accident, a dust monitor with a silicon surface barrier detector (SSBD) is introduced at a site of nuclear fuel facility. However, SSBD frequently produces a false alarm triggered by an electromagnetic noise generator. For high-reliable dust monitoring, we developed an particle spectrometer based on the GPS scintillator plate with PMT. Our developed spectrometer consists of a cerium doped GdSiO (GPS) scintillator plate and a Photomultiplier Tube (PMT). The GPS scintillator plate was hexagonal in shape and 50 mm in diameter and a scintillator layer was approximately 40 um. An Am source with 5.5 MeV particle, Rn progeny collected air filter, and PuO particle were measured by developed spectrometer. The energy resolution for 5.5-MeV particles was 11.9% FWHM. The radon progeny nuclide reduction ratio (Rratio) was improved compared with ZnS(Ag) based spectrometer, so that Pu and Rn progeny can be effectively distinguished. Thus, our developed spectrometer will be high-reliable dust monitor for detecting Pu contamination.