Alpha-recoil track formation on muscovite and measurement of recoil-range using 252Cf-sources

Abstract Registration of alpha-recoil tracks on a muscovite detector was examined using thin 252 Cf-sources, prepared by an electroplating technique from an isopropanol medium. The mica detectors, exposed to alpha-recoil atoms ( 248 Cm) and fission fragments arising from the 252 Cf-source in a vacuum, were chemically etched with an HF solution to reveal shallow pits due to alpha-recoil atoms in addition to the ordinary fission tracks. The ratios (Rt) of alpha-recoil tracks to fission tracks in a fixed area were measured to determine the registration efficiency of alpha-recoil atoms, which has previously been ambiguous despite its very important and basic nature. By comparing the highest Rt-value among the results from various 252 Cf-source thicknesses with a theoretical Rt-value from known nuclear data of 252 Cf, the registration efficiency of alpha-recoil atoms was estimated to be over 57% for the singly recoiled atom 248 Cm, which has a recoil energy of 398 eV/nucleon. Subsequently, the change of Rt-values with increasing thickness of a gold film on a 252 Cf-source was utilized to determine the recoil range of 248 Cm in gold. The extrapolated thickness that yields no recoil-tracks on mica detector gives the recoil range in gold as 138 A, which agrees wellewith the calculated result from the LSS-theoretical equation.