A study on La-doped PbWO4 scintillating crystal

The changes of defects in PbWO4 crystal caused by La dopant have been studi ed by means of positron annihilation lifetime and X-ray photoelectron spect rum (XPS). The results show that La dopant enhance the concentration of lea d vacancy (V-Pb) which can be described as the positron capture center in P bWO4 crystal,and lead vacancy will furthermore introduce low-valent oxygen center. We discuss the mechanism of La doped in PbWO4, and consider that ox ygen vacancy is restrained by doping of La, while lead vacancy density is i ncreased by La dopant.