Using photons for non-destructive testing of thick materials: a simulation study

Positron annihilation spectroscopy using positron annihilation lifetimes has been successfully studied for non-destructive material testing. A positron inspection probe is annihilated with an electron at the front of the material. The application of the positron lifetime method is restricted to thin materials. A photon with energy exceeding 1.02 MeV reaches the materials' depth and can produce a positron through γ-conversion. Such a photon-produced positron is a probe for thick materials. The probability of γ-conversion, however, is low. The method of photon-produced positron annihilation lifetimes is restricted by statistics. We estimated the expected number of events and the statistical uncertainties of the lifetime measurements for a non-destructive test, such as an SUS316 fatigue monitoring, to construct a fatigue-monitoring system.