A method for obtaining the pure annihilation peak of 22Na radioisotope

By means of pulse separation technique, the annihilation gamma ray peak, which has great importance for positron annihilation lifetime spectroscopy (PALS), was discriminated from the superimposed photon spectrum generated by Compton effect, backscattering, and background in the 0.5 MeV energy region. Energy resolution of 4.5% was obtained for the discriminated annihilation peak of 22Na positron emitter radioisotope.