On a problem of assumed 232mPa isomer characteristicsE.F. Fomushkin, M.F. Andreev and S.N. Abramovich
All-Russia Scientific Research Institute of Experimental Physics, Sarov, Russia
Published online: 21 May 2008
To study fission characteristics of protactinium-232, the isotope under investigation was built up in the 232Th(p, n) reaction at a proton energy of Ep ≈ 11.5 MeV. At irradiating the layer by thermal and resonance neutrons the short-lived components with a half-decay period of ~ 6 hours were found in the yields of fission fragments. The totality of experimental data can be explained by the fact that at the thorium-232 bombardment by accelerated protons the protactinium-232 nuclei are formed in the isomer state with a half-life of T1/2 ≈ 2.3 hour. The isomer of 232mPa decays approximately with the similar probability by isomer transition to the ground state 232Pa and, as a result of α-decay, to the isotope 228Ac (T1/2 = 6.15 hour).
© CEA 2008