Development of scintillator plates with high energy resolution for alpha particles made of GPS scintillator grains

Abstract

a b s t r a c tA scintillator plate with high energy resolution was developed to produce an alpha particle monitor used in nuclear fuel reprocessing plants and mixed plutonium-uranium oxide (MOX) fuel plants. Grains of a Gd 2 Si 2 O 7 (GPS) scintillator of several 10 to 550 μm were fixed on a glass substrate and were then mechanically polished. By increasing the size of scintillator grains and removing fine powders, the collected light yield and energy resolution for alpha particles were drastically improved. Energy resolution of 9.3% was achieved using average grain size of 91 μm. Furthermore, the ratios between counts in a peak and total counts were improved by more than 60% by the further increase of grain size and adoption of mechanically polished surfaces on both sides. Beta and gamma ray influences were suppressed sufficiently by the thin 100 μm scintillator plates.

Performance comparison of scintillators for alpha particle detectors

“…GAGG is a single-crystal structure. In contrast, since GPS has scintillator grains fixed on a glass plate [10], the scintillation light may be inflected or refracted on the border of the scintillator grains, causing a loss of scintillation light in the scintillator. Even though GPS suffered a loss of scintillation light in the scintillator, the energy resolution of GAGG and GPS showed no significant difference.…”

“…Recently, a cerium-doped Gd 2 Si 2 O 7 (GPS) has been developed that is suitable for alpha particle detectors because it has high light output to alpha particles [9][10] and improved performance [11]. Because light yield of GPS was reported to be 4.4 times higher than that of BGO scintillator [10] and the light yield of the BGO is 8200 photons/MeV [2], the light yield of the GPS would be about 36000 photons/MeV. We tested four kinds of scintillators for alpha particles including a GPS coupling them with photodetectors and evaluated the best combinations in term of response to alpha particles.…”

An alpha particle detector based on a GPS mosaic scintillator plate for continuous air monitoring in plutonium handling facilities

“…The authors have developed an alpha particle detector based on a Gd2Si2O7:Ce (ceriumdoped gadolinium pyro-silicate, GPS:Ce) scintillator [11][12][13][14][15] with high light yield instead of the ZnS:Ag scintillator [16]. The GPS scintillator achieved energy resolution of 4.6% and 1.4 times the light yield of a conventional NaI:Tl scintillator for 662 keV gamma rays [17].…”

“…The GPS scintillator achieved energy resolution of 4.6% and 1.4 times the light yield of a conventional NaI:Tl scintillator for 662 keV gamma rays [17]. For 5.5 MeV alpha particles, light yields of 4.4 and 2.0 times compared with those of BGO [18] and YAP scintillator [16] were reported, respectively. The central wavelength of scintillation light from a GPS was 395 nm.…”

“…Fabricating a large scintillator plate, i.e., a 5-cm-square with 100 m thick from a GPS single crystal is difficult. To solve this difficulty, a mosaic scintillator plate made of GPS single crystal grains of around 550 m was developed [16]. These grains were made by smashing a GPS polycrystal grown by a top seeded solution growth method.…”