Eur. Phys. J. A (2009) 42: 375-378
https://doi.org/10.1140/epja/i2008-10761-8

Regular Article - Experimental Physics

Beta-decay study of T_z = - 2 proton-rich nucleus ²⁴Si

¹ Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, 113-0033, Tokyo, Japan
² RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako, 351-0198, Saitama, Japan
³ Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, 700 064, Kolkata, India
⁴ Center for Nuclear Study, University of Tokyo, 7-3-1 Hongo, Bunkyo, 113-0033, Tokyo, Japan
⁵ Department of Physics, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro, 152-8551, Tokyo, Japan
⁶ Department of Physics, Kyushu University, 6-10-1 Hakozaki, Higashi, 812-8581, Fukuoka, Japan

^* e-mail: ichikawa@ribf.riken.jp

Received: 10 December 2008
Revised: 12 February 2009
Accepted: 27 February 2009
Published online: 29 March 2009

Abstract

-decay spectroscopy on a T _z = - 2 proton-rich nucleus ²⁴Si was performed. The decay scheme of ²⁴Si was reconstructed by the -delayed -ray and proton measurements. Two branches to the bound 1₁ ⁺ and 1₂ ⁺ states in ²⁴Al were observed for the first time. The observation of the allowed transition firmly established the spin-parity assignment for the 1₂ ⁺ states. The branching ratios to the 1₁ ⁺ and 1₂ ⁺ states were determined to be 31(4)% and 23.9(15)%, respectively. The branching ratios to three unbound states in ²⁴Al including a new level at 6.735MeV were also determined for the first time. The level structure of ²⁴Al was compared with its mirror nucleus ²⁴Na . The Thomas-Ehrman shift on the 1₂ ⁺ state indicates s -wave dominance in the state as well as a characteristic behavior of the weakly bound s -wave proton in ²⁴Al .