Search for low lying dipole strength in the neutron rich nucleus $^{26}$Ne

J. Gibelin; D. Beaumel; T. Motobayashi; N. Aoi; H. Baba; Y. Blumenfeld; Z. Elekes; S. Fortier; N. Frascaria; N. Fukuda; T. Gomi; K. Ishikawa; Y. Kondo; T. Kubo; V. Lima; T. Nakamura; A. Saito; Y. Satou; E. Takeshita; S. Takeuchi; T. Teranishi; Y. Togano; A. M. Vinodkumar; Y. Yanagisawa; K. Yoshida

doi:10.1016/j.nuclphysa.2007.01.076

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arXiv · 0705.1753

Search for low lying dipole strength in the neutron rich nucleus $^{26}$Ne

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Abstract

Coulomb excitation of the exotic neutron-rich nucleus $^{26}$Ne on a $^{nat}$Pb target was measured at 58 A.MeV in order to search for low-lying E1 strength above the neutron emission threshold. Data were also taken on an $^{nat}$Al target to estimate the nuclear contribution. The radioactive beam was produced by fragmentation of a 95 A.MeV $^{40}$Ar beam delivered by the RIKEN Research Facility. The set-up included a NaI gamma-ray array, a charged fragment hodoscope and a neutron wall. Using the invariant mass method in the $^{25}$Ne+n channel, we observe a sizable amount of E1 strength between 6 and 10 MeV. The reconstructed $^{26}$Ne angular distribution confirms its E1 nature. A reduced dipole transition probability of B(E1)=0.49$\pm$0.16 $e^2fm^2$ is deduced. For the first time, the decay pattern of low-lying strength in a neutron-rich nucleus is obtained. The results are discussed in terms of a pygmy resonance centered around 9 MeV.

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J. Gibelin, D. Beaumel, T. Motobayashi, N. Aoi, H. Baba, Y. Blumenfeld, Z. Elekes, S. Fortier, N. Frascaria, N. Fukuda, T. Gomi, K. Ishikawa, Y. Kondo, T. Kubo, V. Lima, T. Nakamura, A. Saito, Y. Satou, E. Takeshita, S. Takeuchi, T. Teranishi, Y. Togano, A. M. Vinodkumar, Y. Yanagisawa, K. Yoshida. 2007-05-12. Search for low lying dipole strength in the neutron rich nucleus $^{26}$Ne. https://doi.org/10.1016/j.nuclphysa.2007.01.076

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