RESPONSE OF NE213 LIQUID SCINTILLATION DETECTORS TO HIGH-ENERGY PHOTONS (E-GAMMA-GREATER-THAN 3 MEV)

Three different liquid scintillation detectors NE213 with volumes vary ing by a factor of 32 were investigated for their response to high-ene rgy photons. Experimental data were taken in the 4.44 MeV and 6-7 MeV calibration fields at the PTB accelerator facility. Comparison with re sponse functions simulated with the EGS4 code including the PRESTA rou tine showed excellent agreement in shape, indicating that the wall eff ects which strongly increase with the increasing photon energy and dec reasing dimensions of the detector are properly taken into account. Th e photon fluence determined on the basis of these calculations agreed reasonably well with the reference data obtained with a calibrated Ge detector. In addition, a significant nonlinearity of the light output as a function of the energy deposited was observed for all detector si zes, and in future this should be included in the calculations. Furthe r investigations are required for even higher photon energies.