Stirling cycle cryogenic cooler used with accelerator for radiation effects in thin films

A new approach is presented relating to the adaptation of a miniature closed cycle cooler and its associated control equipment to accelerator produced low temperature radiation effects in solids. The cooler is capable of operating between 20°K and 300°K with temperature control of 0.02°K within this interval. The system has been used with beams of 150 keV protons on thin films of oxygen and nitrogen doped tantalum, where changes in film conductance are used as a measure of the damage effects. A description of the cryogenic system is presented along with operational characteristics. Typical results are also presented for conductivity-fluence measurements, isochronal annealing, and radiation effects on temperature coefficient of resistivity.