First observation of an isomeric state in proton drip-line nucleus ²⁶P

¹ 1Department of Physics, Tokyo University of Science, Noda 278-8510, Japan
² Department of Physics, Osaka University, Toyonaka 560-0043, Japan
³ Department of Physics, Niigata University, Niigata 950-2102, Japan
⁴ National Institute of Radiological Sciences, Chiba 263-8555, Japan
⁵ Department of Physics, Saitama University, Saitama 338-3570, Japan
⁶ RI center, Niigata University, Niigata 951-8510, Japan
⁷ Gesellschaft für Schwerionenforschung GSI, 64291 Darmstadt Germany

^a e-mail: dnishimura@rs.tus.ac.jp

Published online: 20 March 2014

Abstract

An isomeric state in the proton drip-line nucleus ²⁶P has been observed by the γ-ray spectroscopy. The γ-ray energy and the half-life are 164.4 ± 0.1 keV and 120 ± 9 ns, respectively. For the isomeric transition of the mirror nucleus ²⁶Na, the γ-ray energy of 82.40 ± 0.04 keV and the half-life of 4.35 ± 0.16 μs are also revised. Comparing the experimental reduced transition probabilities of ²⁶Na and ²⁶P with theoretical ones calculated by the shell model with the USDA interaction, the spin-parity (J^π) of the isomeric state in ²⁶P is most likely to be 1⁺.