α decay of the new isotope 204Ac

• DOI: 10.1016/j.physletb.2022.137484
• Publication Date: 2022-10-04T23:35:06Z
• Authors: M.H. Huang; Z.G. Gan; Z.Y. Zhang; L. Ma; J.G. Wang; M.M. Zhang; H.B. Yang; C.L. Yang; X.Y. Huang; Z. Zhao; S.Y. Xu; L.X. Chen; X.J. Wen; Y.F. Niu; C.X. Yuan; Y.L. Tian; Y.S. Wang; J.Y. Wang; M.L. Liu; Y.H. Qiang; W.Q. Yang; H.B. Zhang; Z.W. Lu; S. Guo; W.X. Huang; Y. He; Z.Z. Ren; S.G. Zhou; X.H. Zhou; H.S. Xu; V.K. Utyonkov; A.A. Voinov; Yu.S. Tsyganov; A.N. Polyakov
• Keywords: Physics; QC1-999; Neutron-deficient; 0103 physical sciences; α-particle energy; Gas-filled recoil separator; Excitation function; New isotope; Half-life; 01 natural sciences

A new proton-unbound isotope 204Ac was produced in the fusion-evaporation reaction Tm(40169Ca,5n)204Ac and identified via the recoil-α correlation at the gas-filled recoiled separators SHANS2 and SHANS. The excitation function for producing 204Ac was measured and the optimal beam energy was evaluated to be 212 MeV. Nineteen ER - α1 - α2 - α3 decay chains were observed for this isotope. Based on these chains, the α-particle energy and half-life of 204Ac were determined to be 7948(15) keV and 7.4−1.4+2.2 ms, respectively. Both are consistent with the theoretical prediction. The reduced α-decay width was deduced to be 49−15+10 keV, which indicates a favored α decay for 204Ac. In addition, more precise decay properties of Eα = 7883(15) keV and T1/2 = 7.7−1.6+2.7 ms were obtained for 205Ac.