Recoil distance half-life measurements of the excited states in $^{145}$Sm

A.M. El-Badry; T. Kuroyanagi; S. Mitarai; A. Odahara; Y. Gono; S. Morinobu; K. Ogawa

doi:doi:10.1007/s100500050159

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2019 Impact factor 2.176

Hadrons and Nuclei

Eur. Phys. J. A 3, 133-138

Recoil distance half-life measurements of the excited states in ¹⁴⁵Sm

A.M. El-Badry¹ - T. Kuroyanagi¹ - S. Mitarai¹ - A. Odahara¹ - Y. Gono¹ - S. Morinobu¹ - K. Ogawa²

¹ Department of Physics,Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan
² Department of physics, Chiba University, Chiba 263, Japan

Received: 9 September 1997 / Revised version: 12 June 1998 Communicated by K. Nakai

Abstract
A recoil distance method was used to measure half-lives of the excited states of ¹⁴⁵Sm. The reaction used was ¹³⁹La(¹⁰B, 4n)¹⁴⁵Sm. A plunger system was used. Half-lives were determined for two excited states for the first time. The yrast 27/2⁺ state was found to have a half-life of 1.1 $\pm$ 0.2 ns corresponding to the retardation of 3.1 $\times$ 10^-4 comparing with the single particle estimate of M1. The excitation energy of this state was well reproduced by the shell model calculation having a mixed configuration of [ $\pi$ {h_11/2(g_7/2)^-2 (d_5/2)^-1 }₁₀-, $\nu$ f_7/2] + [ $\pi$ {h_11/2(g_7/2)^-1}₉-, $\nu$ h_9/2]. Another retarded E1 transition was also found in a decay of a 21/2⁺ state. Its retardation was 1.6 $\times$ 10^-4 comparing with the single particle value.