Physics Letters B (May 2017)
Observation of isoscalar and isovector dipole excitations in neutron-rich 20O
- N. Nakatsuka,
- H. Baba,
- T. Aumann,
- R. Avigo,
- S.R. Banerjee,
- A. Bracco,
- C. Caesar,
- F. Camera,
- S. Ceruti,
- S. Chen,
- V. Derya,
- P. Doornenbal,
- A. Giaz,
- A. Horvat,
- K. Ieki,
- T. Inakura,
- N. Imai,
- T. Kawabata,
- N. Kobayashi,
- Y. Kondo,
- S. Koyama,
- M. Kurata-Nishimura,
- S. Masuoka,
- M. Matsushita,
- S. Michimasa,
- B. Million,
- T. Motobayashi,
- T. Murakami,
- T. Nakamura,
- T. Ohnishi,
- H.J. Ong,
- S. Ota,
- H. Otsu,
- T. Ozaki,
- A. Saito,
- H. Sakurai,
- H. Scheit,
- F. Schindler,
- P. Schrock,
- Y. Shiga,
- M. Shikata,
- S. Shimoura,
- D. Steppenbeck,
- T. Sumikama,
- I. Syndikus,
- H. Takeda,
- S. Takeuchi,
- A. Tamii,
- R. Taniuchi,
- Y. Togano,
- J. Tscheuschner,
- J. Tsubota,
- H. Wang,
- O. Wieland,
- K. Wimmer,
- Y. Yamaguchi,
- K. Yoneda,
- J. Zenihiro
Affiliations
- N. Nakatsuka
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
- H. Baba
- RIKEN Nishina Center, Saitama 351-0198, Japan
- T. Aumann
- Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
- R. Avigo
- INFN Sezione di Milano, I-20133 Milano, Italy
- S.R. Banerjee
- Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Kolkata, 700064, India
- A. Bracco
- INFN Sezione di Milano, I-20133 Milano, Italy
- C. Caesar
- Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
- F. Camera
- INFN Sezione di Milano, I-20133 Milano, Italy
- S. Ceruti
- INFN Sezione di Milano, I-20133 Milano, Italy
- S. Chen
- School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China
- V. Derya
- Institut für Kernphysik, Universität zu Köln, D-50937 Köln, Germany
- P. Doornenbal
- RIKEN Nishina Center, Saitama 351-0198, Japan
- A. Giaz
- INFN Sezione di Milano, I-20133 Milano, Italy
- A. Horvat
- Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
- K. Ieki
- Department of Physics, Rikkyo University, Tokyo 171-8501, Japan
- T. Inakura
- Department of Physics, Niigata University, Niigata 950-2181, Japan
- N. Imai
- Center for Nuclear Study, The University of Tokyo, Tokyo 113-0033, Japan
- T. Kawabata
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
- N. Kobayashi
- Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
- Y. Kondo
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
- S. Koyama
- Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
- M. Kurata-Nishimura
- RIKEN Nishina Center, Saitama 351-0198, Japan
- S. Masuoka
- Center for Nuclear Study, The University of Tokyo, Tokyo 113-0033, Japan
- M. Matsushita
- Center for Nuclear Study, The University of Tokyo, Tokyo 113-0033, Japan
- S. Michimasa
- Center for Nuclear Study, The University of Tokyo, Tokyo 113-0033, Japan
- B. Million
- INFN Sezione di Milano, I-20133 Milano, Italy
- T. Motobayashi
- RIKEN Nishina Center, Saitama 351-0198, Japan
- T. Murakami
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
- T. Nakamura
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
- T. Ohnishi
- RIKEN Nishina Center, Saitama 351-0198, Japan
- H.J. Ong
- Research Center for Nuclear Physics, Osaka University, Osaka 567-0047, Japan
- S. Ota
- Center for Nuclear Study, The University of Tokyo, Tokyo 113-0033, Japan
- H. Otsu
- RIKEN Nishina Center, Saitama 351-0198, Japan
- T. Ozaki
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
- A. Saito
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
- H. Sakurai
- Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
- H. Scheit
- Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
- F. Schindler
- Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
- P. Schrock
- Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
- Y. Shiga
- Department of Physics, Rikkyo University, Tokyo 171-8501, Japan
- M. Shikata
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
- S. Shimoura
- Center for Nuclear Study, The University of Tokyo, Tokyo 113-0033, Japan
- D. Steppenbeck
- RIKEN Nishina Center, Saitama 351-0198, Japan
- T. Sumikama
- RIKEN Nishina Center, Saitama 351-0198, Japan
- I. Syndikus
- Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
- H. Takeda
- RIKEN Nishina Center, Saitama 351-0198, Japan
- S. Takeuchi
- RIKEN Nishina Center, Saitama 351-0198, Japan
- A. Tamii
- Research Center for Nuclear Physics, Osaka University, Osaka 567-0047, Japan
- R. Taniuchi
- Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
- Y. Togano
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
- J. Tscheuschner
- Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
- J. Tsubota
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
- H. Wang
- RIKEN Nishina Center, Saitama 351-0198, Japan
- O. Wieland
- INFN Sezione di Milano, I-20133 Milano, Italy
- K. Wimmer
- Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
- Y. Yamaguchi
- Center for Nuclear Study, The University of Tokyo, Tokyo 113-0033, Japan
- K. Yoneda
- RIKEN Nishina Center, Saitama 351-0198, Japan
- J. Zenihiro
- RIKEN Nishina Center, Saitama 351-0198, Japan
- DOI
- https://doi.org/10.1016/j.physletb.2017.03.017
- Journal volume & issue
-
Vol. 768,
no. C
pp. 387 – 392
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 (O20+Au) and a dominant isoscalar probe (O20+α) were compared and analyzed by the distorted-wave Born approximation to extract independently the isovector and isoscalar dipole strengths. Two known 1− states with large isovector dipole strengths at energies of 5.36(5) MeV (11−) and 6.84(7) MeV (12−) were also excited by the isoscalar probe. These two states were found to have different isoscalar dipole strengths, 2.70(32)% (11−) and 0.67(12)% (12−), respectively, in exhaustion of the isoscalar dipole-energy-weighted sum rule. The difference in isoscalar strength indicated that they have different underlying structures.
Keywords
