Energy dependence of gamma detection efficiency for SED R-12

Superheated emulsion detector consists of droplets of two metastable states, one with a much shorter life-time (second metastable state) than the other (normal metastable state). The SED made from R-12 (CCl2F2) is sensitive to gamma rays near 40 °C. Gamma detection sensitivity of superheated R-12 increases monotonically beyond this threshold temperature. The radiation induced nucleation frequency of normal superheated drops of R-12 is studied in the temperature range 45–58 °C for gamma rays of energy 59.54 and 662 keV obtained from 241Am and 137Cs sources, respectively. It is observed that the radiation induced nucleation frequency and hence the gamma detection efficiency increase with temperature and with the energy of the gamma rays.