"Investigating The Light Collection From Lead Tungstate (PWO) Scintillators at Low Temperatures"
The light collection of scintillation light in crystals of PWO for different locations of radiation on the crystal and at temperatures between 21 degrees Celsius and -23 degrees Celsius has been investigated for two crystals of different shapes. The number of photons reaching the PM tube varied with point of interaction in the crystal and with the temperature of the crystal. The average increase in number of photoelectrons between the temperatures 21 degrees Celsius and -23 degrees Celsius was 80(4)% for a tapered crystal and 97(4)% for a straight crystal. The average increase in number of photoelectrons at different positions in the crystal was 4.9(5)% for the tapered crystal and 7.9(5)% for the straight crystal. A simulation of the light yield in the material was performed for gamma ray energies between 10 MeV and 2 GeV and the width contributions of light non-uniformity in the crystal and energy leakage from the crystal were investigated. The contribution from light non-uniformity was less than the energy leakage from the crystal for all energies. Both contributions were larger than the statistical contribution at energies above 500 MeV.
