Intensity distribution of scintillation produced by high-energy electrons

Abstract

As a basis of yttrium aluminum garnet (YAG)-TV image-recording systems scintillation properties of single-crystal phosphors (YAG (Y 2Al 5O 12)), yttrium compound (YAlO 3, Y 2SiO 5), powder phosphors and plastic scintillators have been studied in the electron energy range 40 keV – 1 MeV. The scintillation light is measured by a photomultiplier and a pulse height analyzer. All of the energy of 100 kV electrons is absorbed in a single crystal of 100 μm thick and the distribution of pulse heights of light outputs produced by many electrons shows a single peak. However, the distribution changes drastically as the accelerating voltage increases. At 300 kV two peaks appear in the pulse height distribution and at higher accelerating voltage such as 800 kV only one single peak with low pulse height remains. These distributions for high-energy electrons are due to the energy loss of electrons which penetrate the scintillator without much deflection. The variance of the pulse height distribution gives the detective quantum efficiencies which are about 0.9 for 100 kV and about 0.55 for 1000 kV. The energy conversion coefficient is estimated to be 0.01 for the YAG scintillator.