{beta} decay of the proton-rich nucleus {sup 24}Si and its mirror asymmetry

Journal Article · Thu Oct 15 04:00:00 EDT 2009 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.80.044302· OSTI ID:21293915

Ichikawa, Y; Sakurai, H ^[1]; Onishi, T K; Suzuki, D; Iwasaki, H; Nakao, T; Suzuki, H; Suzuki, M K ^[1]; Kubo, T; Aoi, N; Fukuda, N; Motobayashi, T; Yamada, K N ^[2]; Naik, V; Chakrabarti, A ^[3]; Brown, B A ^[4]; Kubono, S; Yamaguchi, H ^[5]; Nakabayashi, T; Nakamura, T ^[6]

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1. Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan)
2. RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
3. Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata-700 064 (India)
4. Department of Physics and Astronomy, and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824-1321 (United States)
5. Center for Nuclear Study, University of Tokyo, RIKEN Campus, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
6. Department of Physics, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro, Tokyo 152-8551 (Japan)

{beta}-decay spectroscopy of the proton-rich nucleus {sup 24}Si was performed. The decay scheme was reconstructed from results of delayed {gamma}-ray and proton measurements. We observed two {beta} branches to bound states in {sup 24}Al for the first time. The branching ratios were determined to be 31(4)% and 23.9(15)% for the 1{sub 1}{sup +} state at 0.426 MeV and the state at 1.090 MeV, respectively. The observation of an allowed transition to the 1.090-MeV state enabled us to firmly determine its spin-parity as 1{sup +}. In the proton measurements performed with the {delta}E-E method, we observed a new unbound level at 6.735 MeV. The branching ratios to three unbound states, including the new level, were also determined for the first time. Based on the decay scheme, the B(GT) values of {sup 24}Si were deduced. The B(GT) values were smaller than those of the mirror nucleus {sup 24}Ne by 22% and 10% for the 1{sub 1}{sup +} and 1{sub 2}{sup +} states, respectively. The mirror asymmetries of B(GT), observed in both the 1{sub 1}{sup +} and the 1{sub 2}{sup +} states, indicate changes in configuration in the wave function associated with the Thomas-Ehrman shift. To clarify the mechanism of this asymmetry, a comparison with shell-model calculations is also discussed. The calculations attribute the changes in configuration to the lowering of the 1s{sub 1/2} orbital.

• OSTI ID: 21293915
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 4 Vol. 80; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALUMINIUM 24
ASYMMETRY
BETA DECAY
BOUND STATE
BRANCHING RATIO
COMPARATIVE EVALUATIONS
CONFIGURATION
GAMMA RADIATION
MIRROR NUCLEI
NEON 24
PROTONS
SHELL MODELS
SILICON 24
SPECTROSCOPY
SPIN
WAVE FUNCTIONS