New β-delayed proton decays in the rare-earth region near the proton drip line

• Published in: Science China. Mathematics Vol. 43; no. 8; pp. 885 - 891
• Main Authors: Xu, Shuwei, Li, Zhankui, Xie, Yuanxiang, Yu, Yong, Pan, Qiangyan, Wang, Chunfang, Xing, Jianping, Ma, Ruichang, Ge, Yuanxiu, Zhang, Tianmei
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer Nature B.V 01.08.2000; Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
• Subjects: Energy spectra; Protons; Rare earth elements; Statistical models; Transportation systems; proton-drip line; β-delayed proton decay; β-delayed proton precursors; ground-state spin and parity
• ISSN: 1006-9283; 1674-7283; 1862-2763; 1869-1862
• DOI: 10.1007/BF02884188

The β-delayed proton precursors125Nd128Pm129Sm,137Gd and139Dy near the proton drip line were produced by the irradiation of92Mo,96Ru and106Cd with an36Ar beam, and conclusively identified for the first time by using proton-gamma coincidence in combination with a He-jet tape transport system. Their half-lives were determined to be 0.60(15)s,1.0(3)s,O.55(10)s,2.2(2)s and 0.6 (2)s, respectively. The measured energy spectra of β-delayed protons and estimated proton branching ratios to the final states in “daughter” nuclei for the precursors125Nd,129Sm,137Gd and139Dy, as well as the previously reported ones for the precursors135Gd and121Ce, were fitted by a statistical model calculation. The ground-state spins and parities of121Ce,125Nd,129Sm,139Gd,137Gd and139Dy were then assigned as 5/2±,5/2±, 1/2± (or 3/2+), 5/2+,7/2+- and 7/2, respectively. The consistency between the experimental spin-parity assignment and the predicted Nilsson diagrams indirectly indicates that the ground states of121Ce,125Nd,129Sm,135Gd,137Gd and139Dy are highly deformed with β2, - 0.3.