Darmstadt 2008 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 50: Kernphysik / Spektroskopie II
HK 50.5: Talk
Friday, March 14, 2008, 15:15–15:30, 2G
Highly excited sharp states in 9B observed in a high-resolution (3He,t) measurement — •Clemens Scholl1, Yoshitaka Fujita2, Tatsuya Adachi2, Peter von Brentano1, Hisanobu Hashimoto3, Kichiji Hatanaka3, Hiroaki Matsubara3, Kohsuke Nakanishi4, Yasuhiro Sakemi3, Yoshihiro Shimbara5, Yukio Shimizu3, Yuji Tameshige3, Atsushi Tamii3, Masaru Yosoi3, and Remco Zegers5,6 — 1Institut für Kernphysik, Universität zu Köln, Deutschland — 2Department of Physics, Osaka University, Japan — 3Research Center for Nuclear Physics, Osaka, Japan — 4CNS, Tokyo University, RIKEN Campus, Wako, Japan — 5NSCL, Michigan State University, East Lansing, USA — 6Department of Physics and Astronomy, MSU, East Lansing, USA
A high energy-resolution 9Be(3He,t)9B experiment was performed at 0∘ and an intermediate incident energy of 140 MeV/nucleon at RCNP Osaka. This setup is a sensitive tool for Gamow-Teller transition strengths. The 2 α + p channel is open even for the ground state of 9B, and thus some of the strongly excited low-lying states have decay widths in the order of 1 MeV. With a high sensitivity obtained by the high-resolution of the (3He,t) reaction however, several weak but sharp states were observed at excitation energies higher than 14 MeV. The weak excitations of these states suggest that they have a different shape structure from the ground state which has a well-developed cluster structure, while the narrow decay widths of these states suggest that a proton decay is prohibited by the isospin selection rule.