CR-39 autoradiographic micromapping of rock sections of various alpha emitters content – calibration approach

The autoradiographic micromapping of rocks with various U and Th contents has been performed by means of CR-39 solid-state nuclear track detector (SSNTD). The optical track density was found to be highly correlated (r = 0.92) with total alpha emitters activity calculated on the basis of field gamma spectrometric measurements of rock outcrops. The method was tested not only for the wide range activities of alpha emitters but various types of surface distribution (including highly radioactive mineral grains) as well.