Gamma-ray response
The typical energy spectra of the Ce doped SHO/SAO eutectic
sample excited by 137Cs gamma-ray and 241Am alpha-ray at room
temperature using the PMT are shown in Fig. 7. The pulse height
of Ce:(Lu,Y)2SiO5 (LYSO) crystal, which has a light output of
28,000 photons/MeV [18] was also measured as a reference. Light
yield was corrected by a quantum efficiency (QE) of the PMT at
the emission wavelength of LYSO (QE = 38%@420 nm) and Ce
doped SHO/SAO eutectic (QE = 39%@410 nm). 5.5 MeV alpha-ray
peak was observed by 241Am excitation and light yield of the eutectic
sample was around 300 photon/5.5 MeV alpha-ray. Photoabsorption
peak was not clearly observed by 137Cs gamma-ray
excitation. Scintillation decay curves were obtained by using the
PMT and digital oscilloscope and the sample was irradiated by
137Cs (Fig. 8). Scintillation decay is approximated by the sum of
two exponentials according to Eq. (1).
IðtÞ ¼XAi exp½t=si; i ¼ 1; 2: ð1Þ
Ratio (%) is calculated by 1s1/(A1s1 + A2s2) 100%. Scintillation
decay time of Ce doped SHO/SAO eutectic was 26.4 ns (45%) with