Annealing Studies of Irradiated Platinum

A field-ion microscope operated at 4.2°K has been used to study defects introduced into 99.9998% pure platinum by fast-neutron irradiation. Damaged or depleted zones have been identified and their concentration and size have been studied as a function of dose and annealing temperature. Direct observations indicate a distribution of zone sizes up to approximately 40 Å in diameter. The density of these zones is linear with dose in the range from ${10}^{16}$-${10}^{18}$ n/${\mathrm{cm}}^2$ ($E>\mathrm{}1.45\mathrm{}$ MeV). Field-ion-microscope studies also reveal that upon annealing through stage-IV recovery, the small depleted zones (