Penetration of gamma-rays

Abstract

The variation of pulse-height spectra was observed under the consecutive treatment of CsI:Tl plane scintillators by different abrasives – with increase of the abrasive grain size the double peaks of the total absorption transferred into the single peaks with acceptable resolution. The light collection simulation of the differently treated surfaces was performed to interpret the experimental results. In simulation the surface relief was represented as a set of micro-facets with slope distribution functions extracted from the experimentally measured reflectance distribution functions. The behavior of the simulated pulse-height spectra in the vicinity of the total absorption peak under the assumption of uniform scintillation distribution in the scintillator volume was in a good agreement with experimental results for different surface treatment conditions. From pulse-height spectrum simulations for different positions of the point light source it was determined that the double peaks in experimental and simulated spectra had been caused by the scintillations in different scintillator areas. The decrease of the light output and the resolution improvement occurred under the input surface treatment of the plane scintillator by the larger abrasive was caused by the increase of the average pass length of light to the output detector window and by the decrease of the difference of this value for the various scintillator areas, respectively.