New <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi></mml:math>-Emitting Isotope <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">U</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>214</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> and Abnormal Enhancement of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi></mml:math>-Particle Clustering in Lightest Uranium Isotopes
Z.Y. Zhang, H. B. Yang, M. H. Huang, Z. G. Gan, Cenxi Yuan, Chong Qi, A. N. Andreyev, M. L. Liu, Long Ma, M. M. Zhang, Y. L. Tian, Y. S. Wang, J. G. Wang, Chen Yang, G. S. Li, Yi Qiang, W. Q. Yang, R. F. Chen, H. B. Zhang, Zitong Lu, X. X. Xu, Luming Duan, Haiyan Yang, Wenxue Huang, Zhong Liu, Xianming Zhou, Yihang Zhang, Han‐Shu Xu, Ning-Xiang Wang, Haoxin Zhou, Xianfei Wen, Siyu Huang, W. Hua, Long Zhu, X. Wang, Yunlong Mao, Xiao-Tao He, S. Y. Wang, W. Z. Xu, Hongjuan Li, Z. Z. Ren, Shan-Gui Zhou
Abstract
A new α-emitting isotope ^{214}U, produced by the fusion-evaporation reaction ^{182}W(^{36}Ar,4n)^{214}U, was identified by employing the gas-filled recoil separator SHANS and the recoil-α correlation technique. More precise α-decay properties of even-even nuclei ^{216,218}U were also measured in the reactions of ^{40}Ar, ^{40}Ca beams with ^{180,182,184}W targets. By combining the experimental data, improved α-decay reduced widths δ^{2} for the even-even Po-Pu nuclei in the vicinity of the magic neutron number N=126 are deduced. Their systematic trends are discussed in terms of the N_{p}N_{n} scheme in order to study the influence of proton-neutron interaction on α decay in this region of nuclei. It is strikingly found that the reduced widths of ^{214,216}U are significantly enhanced by a factor of two as compared with the N_{p}N_{n} systematics for the 84≤Z≤90 and N<126 even-even nuclei. The abnormal enhancement is interpreted by the strong monopole interaction between the valence protons and neutrons occupying the π1f_{7/2} and ν1f_{5/2} spin-orbit partner orbits, which is supported by the large-scale shell model calculation.