The silver-activated zinc sulfide, ZnS(Ag), sensor to detect alpha-particles is normally fabricated by means of heat-melting or epoxy mixing spread. However, the fabrication process is very complicated so that it creates high costs and requires special high-tech equipment to manufacture the detector. For this reason, we have developed a new fabrication method which has the advantages of process simplicity and also high efficiency. The alpha particle response of the detector manufactured by the new spreading method was evaluated at varied thicknesses of ZnS(Ag) and the detection efficiency was better than for other methods like liquid brush method with an Am-241 alpha radiation source. Compared to conventional ZnS(Ag) detectors, the new detector shows a good detection efficiency, and its simple and low cost design makes it an economical and commercial alternative to more expensive alpha survey instruments.

A ZnSe crystal based on a -compound semiconductor has various physical properties: electroluminescent, photoelectric, luminescent and scintillation. Activated ZnSe crystals are highly-efficient scintillators, and they are already being applied to the detecting units of a X-ray introscopy and a dosimetric system. ZnSe-based scintillators have a high absolute light output, and their radiation spectra matches well with the Si-photodiode spectral sensitivity.The present study was performed by using a polished ZnSe and CsI(Tl). ZnSe is a low-density crystal(5.42 g/cm 3). The emission wavelength of ZnSe(Te) is 610 nm and ZnSe(O) is 592 nm. We have fabricated 10x10x1 mm and 10x10x2 mm ZnSe crystals in which the activators were doped with tellurium and oxygen. ZnSe and CsI crystals were mounted on a S3590-08 HAMAMATSU PIN photodiode and an R3479 HAMAMATSU PMT. Teflon tape as a reflector for the PIN photodiode and PMT. Gamma-ray spectrum measurements were performed by using Cs radio isotopes. We have compared the measured spectra of ZnSe and CsI under the same conditions.

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Gadolinium oxyorthsilicate doped with cerium, Gd 2SiO 5 :Ce (GSO:Ce), is a scintillator crystal discovered in 1983, which has excellent properties, high light yield, fast decay time, and good radiation hardness. The Gd 2SiO 5 (GSO) and GSO:Ce (0.5 mole%) single crystals were grown by Czochralski method under argon atmosphere. After the growth, thermal treatment of the GSO crystals was carried out at 1780K for 3 hours under argon atmosphere. The maximum wavelength of the emission spectrum of the GSO:Ce scintillator was 430 nm. The energy resolution of the GSO:Ce scintillator was 9.1 % with PMT, when it was exposed to 137 Cs -ray. The luminescence decay time of the GSO:Ce scintillator has two exponential components with 68.7 ns and 754 ns time constant.