Eur. Phys. J. A (2005) 23: 395-400
https://doi.org/10.1140/epja/i2004-10096-6

Proton-neutron configurations in ^{236g, m}Am and its EC-decay daughter ²³⁶Pu

¹ Advanced Science Research Center, Japan Atomic Energy Research Institute, 319-1195, Tokai, Japan
² Department of Radiologic Science and Engineering, The University of Tokushima, 770-8509, Tokushima, Japan
³ Cyclotron Center, The Institute of Physical and Chemical Research (RIKEN), 351-0198, Wako, Japan
⁴ Department of Chemistry, Niigata University, 950-2181, Niigata, Japan
⁵ Graduate School of Engineering, Hiroshima University, 739-8527, Higashi-Hiroshima, Japan
⁶ Department of Chemistry, Tokyo Metropolitan University, 192-0397, Hachioji, Japan
⁷ Department of Energy Engineering and Science, Nagoya University, 464-8603, Nagoya, Japan

^* e-mail: asai@tandem.tokai.jaeri.go.jp

Received: 4 October 2004
Accepted: 22 October 2004
Published online: 14 December 2004

Abstract

The EC decay of ²³⁶Am has been studied using a gas-jet coupled on-line isotope separator. A half-life analysis revealed that there are two EC-decaying states in ²³⁶Am: the 5^- state with T _1/2 = 3.6(2) min and the (1^-) state with T _1/2 = 2.9(2) min. The 1185.5 keV level in ²³⁶Pu was found to be the K isomer with K ^π = 5^- and t _1/2 = 1.2(3) μs. EC transitions from ^{236g, m}Am to the 1185.5, 1311.5, and 1340.8 keV levels in ²³⁶Pu show small log ft values of 4.9, 5.3, and 4.8, respectively, indicating that the π5/2⁺[642] → ν5/2⁺[633] transition largely contributes to these transitions, and thus, the populated levels should be the π5/2^-[523]π5/2⁺[642] two-quasiparticle states. The K ^π = 0^- octupole band established in ²³⁶Pu is located at higher energy than those in ^238,240Pu, which implies that the octupole correlations become weak at ²³⁶Pu.