GSO: Ce³⁺ scintillator with a high energy resolution

Abstract

It is known that in case of registration of the scintillation light using photomultiplier energy resolution of the scintillation detector can be written as sum of three components, each of them is statistically independent of others: Rin - the value describing the dispersion of the light quantity which is formed in the process of radioluminescence and depends on the scintillator material; Rph - the value describing statistic variations of the number of photoelectrons knocked out from the photocathode by the scintillation photons, it is reversely proportional to the scintillator light output; Rt - the value corresponding to the non-uniformity of the light collection coefficient in different parts of the scintillator volume. In this paper the authors made an attempt to improve energy resolution of GSO(Ce) detector owing to lowering the latter two terms by varying the bulk optical properties and reflection characteristics of the surface by means of annealing. Energy resolution 8.5% by γ-line 662 keV from ¹³⁷Cs was achieved due to improvement of transparency and especially selected surface roughness of the cylindrical Gd₂SiO₅:Ce scintillator 27 mm in diameter and 90 mm long.