John E. Esterl

Confirmed proton radioactivity of 53Com

Abstract Proton-induced reactions on 54Fe produce a proton activity [1.57±0.03 MeV; 242±15 ms] with a threshold of 26.3±0.4 MeV which can only arise from 53Com. Failure to detect positron-proton coincidences in the decay of this isomer establishes its direct proton radioactivity.

Further results on the proton radioactivity of 53mCo

Abstract Additional studies on the proton radioactivity of the 247 ± 12 msec isomer 53m Co lead to an improved estimate of ≈ 17 sec for its partial half-life for emission of 1.59 ± 0.03 MeV protons to the 52 Fe ground state. An upper limit of 1 250 for the ratio of direct proton decay to the 52 Fe ∗ (2 + , 0.84 MeV) state relative to decay to the 52 Fe(g.s.) can be set.

Beta-delayed proton decay of 13O: A violation of mirror symmetry☆

Beta-delayed protons, Elab > 1.2 MeV, were observed following the decay of 13O, τ12 = 8.95±0.20 ms. Comparison of 13O decay-rates with those of the mirror nuclide 13B indicates a 15% deviation from mirror symmetry.

A HIGH-RESOLUTION DETECTION SYSTEM FOR SHORT-LIVED GASEOUS ACTIVITIES

Abstract A fast gas-sweeping system has been developed which enables activities to be transported up to 5 m from the target position in 50–100 ms. It has been used along with a cooled semiconductor-counter telescope to obtain delayed-proton spectra in which the energy resolution was limited to 45 keV by kinematic effects. The remote counting location also permits use of a Ge(Li) detector without fear of radiation damage. Several different high-yield target configurations are described, including a sulfur target that is useful for prolonged high-intensity bombardments.