1. Observation of isoscalar and isovector dipole excitations in neutron-rich 20 O
- Author
-
K. Yoneda, Ryo Taniuchi, Susumu Shimoura, H. Baba, T. Murakami, J. Tsubota, R. Avigo, Hideaki Otsu, Yosuke Kondo, Agnese Giaz, Noritsugu Nakatsuka, C. Caesar, Takeo Kawabata, F. Camera, S. Ceruti, Y. L. Yamaguchi, Hooi Jin Ong, Kathrin Wimmer, A. Horvat, Juzo Zenihiro, J. Tscheuschner, T. Ozaki, Toshiyuki Sumikama, Takashi Nakamura, B. Million, H. Wang, F. Schindler, Hiroyuki Takeda, A. Bracco, Heiko Scheit, Hiroyoshi Sakurai, Tsuyoshi Ohnishi, Shoko Koyama, M. Shikata, I. Syndikus, N. Imai, T. Motobayashi, Kazuo Ieki, T. Inakura, Yoshiaki Shiga, V. Derya, Shuichi Ota, P. Doornenbal, Shoichiro Masuoka, Yasuhiro Togano, P. Schrock, Masafumi Matsushita, S. Michimasa, Oliver Wieland, Shao-Long Chen, David Steppenbeck, Atsumi Saito, Satoshi Takeuchi, S.R. Banerjee, Thomas Aumann, M. Kurata-Nishimura, Atsushi Tamii, and Nagao Kobayashi
- Subjects
O20 ,Nuclear and High Energy Physics ,Inelastic α scattering ,Isoscalar ,Nuclear Theory ,Inelastic alpha scattering ,01 natural sciences ,Nuclear physics ,0103 physical sciences ,ddc:530 ,Neutron ,Born approximation ,010306 general physics ,Physics ,Isovector ,010308 nuclear & particles physics ,Inelastic α scattering ,Low-energy dipole excitation ,Virtual-photon excitation ,lcsh:QC1-999 ,Dipole ,O-20 ,Isospin ,Excited state ,(20)O ,Sum rule in quantum mechanics ,Atomic physics ,lcsh:Physics - Abstract
The isospin characters of low-energy dipole excitations in neutron-rich unstable nucleus 20O were investigated, for the first time in unstable nuclei. Two spectra obtained from a dominant isovector probe (View the MathML sourceO20+Au) and a dominant isoscalar probe (View the MathML sourceO20+α) were compared and analyzed by the distorted-wave Born approximation to extract independently the isovector and isoscalar dipole strengths. Two known 1−1− states with large isovector dipole strengths at energies of 5.36(5) MeV (View the MathML source11−) and 6.84(7) MeV (View the MathML source12−) were also excited by the isoscalar probe. These two states were found to have different isoscalar dipole strengths, 2.70(32)% (View the MathML source11−) and 0.67(12)% (View the MathML source12−), respectively, in exhaustion of the isoscalar dipole-energy-weighted sum rule. The difference in isoscalar strength indicated that they have different underlying structures. ispartof: Physics Letters B vol:768 pages:387-392 status: published
- Published
- 2017
- Full Text
- View/download PDF