A Detection technique for low-energy gamma rays from alpha emitters in background radiation environment

Morishita, Yuki   ; Yamada, Tsutomu*; Nakasone, Takamasa*; Kanno, Marina*; Sasaki, Miyuki  ; Sanada, Yukihisa   ; Torii, Tatsuo*  

The Fukushima Daiichi Nuclear Power Station's decommissioning requires thorough inspection of piping for contamination, including alpha nuclides. External alpha particle measurements are impossible, necessitating gamma-ray detection methods. A phoswich detector for low-energy gamma-ray detection was developed and validated experimentally at a nuclear fuel facility. The detector was designed considering energy deposition characteristics. The detector comprises YAlO:Ce and BiGeO scintillators with a photomultiplier tube for signal amplification. Measurement and simulation results show correlation between scintillator energy depositions for different gamma-ray energies. Pulse Shape Discrimination (PSD) plots distinguish alpha particles and gamma-rays, confirming simulation predictions. Nuclear fuel facility measurements exhibit higher energy deposition in the first scintillator layer. This suggests potential for developing a sensitive low-energy gamma-ray detector using scintillator combinations. Future work aims to optimize detector design and conduct field tests for validation.