On a problem of assumed ^232mPa isomer characteristics

Abstract

Abstract. To study fission characteristics of protactinium-232, the isotope under investigation was built up in the 232 Th(p, n) reaction at a proton energy of E p ≈ 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 T 1/2 ≈ 2.3 hour. The isomer of 232m Pa decays approximately with the similar probability by isomer transition to the ground state 232 Pa and, as a result of α-decay, to the isotope 228 Ac (T 1/2 = 6.15 hour).

Measurement of the 242gAm (T1/2=16.02 hour) fission cross section

“…In the investigations of fission characteristics of short-lived odd-odd nuclei undertaken in VNIIEF the nuclides of 232 Pa and 238 Np were produced in (p,n) reactions; metal plates of 232 Th and 238 U were irradiated by accelerated protons [4]. The irradiated surface of plates was etched, and the corresponding nuclide was isolated using radiochemical methods.…”