J.G. Wang, Z.C. Li, Z.Y. Zhang, Z.G. Gan, A.N. Andreyev, M.H. Huang, L. Ma, M.M. Zhang, H.B. Yang, C.L. Yang, Y.H. Qiang, Z.H. Li, X.Y. Huang, G. Xie, L. Z. Zhu, H. Zhou, X. Zhang, J.H. Zheng, S.Y. Xu, Z. -C. Zhao, L.C. Sun, F. Guan, X.L. Wu, W.X. Huang, Y.L. Tian, Y.S. Wang, J.Y. Wang, Z.W. Lu, Y. He, L.T. Sun, Z.Z. Ren, SG Zhou, V.K. Utyonkov, A.A. Voinov, Yu. S. Tsyganov, A.V. POLYAKOV
The new isotopes, 235 Bk and its α -decay daughter 231 Am, were investigated using the gas-filled recoil separator SHANS2. They were identified by measuring radioactive decay chains originating from 235 Bk, which was produced via the 197 Au( 40 Ar, 2n) 235 Bk reaction. Three correlated α -decay chains were assigned to 235 Bk, from which the α -particle energy of 235 Bk was measured to be 7632(17) keV. For 231 Am, the α -particle energy and half-life were determined to be 7109(18) keV and 75 − 30 + 137 s, respectively. The α -decay branching ratio of 231 Am was evaluated as 17 − 15 + 65 % . A systematic analysis reveals significant discrepancies between the experimental data and the WS4+RBF theoretical predictions for the isotopes of Bk and Am, which warrant further investigation.