Nuclear Solid State Physics

In this project atomic defects are studied by positron annihilation spectroscopy. From the measurement of the positron lifetime one can get information on the type of defect (single vacancy or bigger vacancy complexes) and on the concentration of these defects. The sensitivity is in the range 10/-6/ to 10/-4/ defects cm/-3/. In polymers the size of the free volume can be estimated. The doppler broadening of the annihilation radiation, especially the 2-dimensional measurement, yields information on the chemical surrounding of the defect.