Simulation study of non-destructive testing method for thick materials using positrons from muon decays

In this paper, we propose a non-destructive testing method with positron annihilation lifetimes for thick materials. The positron annihilation lifetime is sensitive to the defect density of atoms or dislocations. A positron from a radiation source is annihilated with an electron at the front surface of the materials under investigation. The application of the positron lifetime method is restricted to thin materials. A positive muon can readily penetrate thick materials and decay into a positron and two neutrinos. The positrons from the muon decays are annihilated with electrons in the materials. The positron annihilation method using muon decays can be applied to thick materials. We estimated the efficiencies and the statistical uncertainties of the lifetime measurements for this method using a GEANT simulation. Some technical issues pertaining to the estimation of the defect distribution with this method are discussed.