Detection of 10- to 100-MeV photons with lead-glass cherenkov counters

Abstract We describe the use of a 10 × 10 × 15cm 3 lead-glass Cherenkov counter as a detector of photons with energies as low as 10 MeV. A procedure for calibrating the efficiency of the counter without the use of tagged photons is presented. Using electron-beam measurements and a Monte Carlo calculation, we find that a normally-incident photon is detected with an efficiency of 62% at 15 MeV and 87% at 25 MeV.