Discovery of New Isotopes <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mrow><mml:mi>Os</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>160</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">W</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>156</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math>: Revealing Enhanced Stability of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>N</mml:mi><mml:mo>=</mml:mo><mml:mn>82</mml:mn></mml:mrow></mml:math> Shell Closure on the Neutron-Deficient Side
H. B. Yang, Z. G. Gan, Y. J. Li, M. L. Liu, S. Y. Xu, C. W. Liu, M. M. Zhang, Z.Y. Zhang, M. H. Huang, Cenxi Yuan, S. Y. Wang, Long Ma, J. G. Wang, Xiangna Han, Aman Rohilla, Shen Zuo, X. Xiao, X. B. Zhang, Long Zhu, Z.F. Yue, Y. L. Tian, Yonghong Wang, Chen Yang, Zihang Zhao, X. Y. Huang, Zichao Li, L. C. Sun, J. Y. Wang, Herun Yang, Zitong Lu, W. Q. Yang, Xin‐Hui Zhou, Wenxue Huang, Ning Wang, Shan-Gui Zhou, Z. Z. Ren, X. Xu
Abstract
Using the fusion-evaporation reaction ^{106}Cd(^{58}Ni,4n)^{160}Os and the gas-filled recoil separator SHANS, two new isotopes _{76}^{160}Os and _{74}^{156}W have been identified. The α decay of ^{160}Os, measured with an α-particle energy of 7080(26) keV and a half-life of 201_{-37}^{+58} μs, is assigned to originate from the ground state. The daughter nucleus ^{156}W is a β^{+} emitter with a half-life of 291_{-61}^{+86} ms. The newly measured α-decay data allow us to derive α-decay reduced widths (δ^{2}) for the N=84 isotones up to osmium (Z=76), which are found to decrease with increasing atomic number above Z=68. The reduction of δ^{2} is interpreted as evidence for the strengthening of the N=82 shell closure toward the proton drip line, supported by the increase of the neutron-shell gaps predicted in theoretical models.