A two-neutron halo is unveiled in $^{29}$F

S. Bagchi; R. Kanungo; Y. K. Tanaka; H. Geissel; P. Doornenbal; W. Horiuchi; G. Hagen; T. Suzuki; N. Tsunoda; D. S. Ahn; H. Baba; K. Behr; F. Browne; S. Chen; M. L. Cortés; A. Estradé; N. Fukuda; M. Holl; K. Itahashi; N. Iwasa; G. R. Jansen; W. G. Jiang; S. Kaur; A. O. Macchiavelli; S. Y. Matsumoto; S. Momiyama; I. Murray; T. Nakamura; S. J. Novario; H. J. Ong; T. Otsuka; T. Papenbrock; S. Paschalis; A. Prochazka; C. Scheidenberger; P. Schrock; Y. Shimizu; D. Steppenbeck; H. Sakurai; D. Suzuki; H. Suzuki; M. Takechi; H. Takeda; S. Takeuchi; R. Taniuchi; K. Wimmer; K. Yoshida

doi:10.1103/physrevlett.124.222504

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arXiv · 2005.09492

A two-neutron halo is unveiled in $^{29}$F

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Abstract

We report the measurement of reaction cross sections ($\sigma_R^{\rm ex}$) of $^{27,29}$F with a carbon target at RIKEN. The unexpectedly large $\sigma_R^{\rm ex}$ and derived matter radius identify $^{29}$F as the heaviest two-neutron Borromean halo to date. The halo is attributed to neutrons occupying the $2p_{3/2}$ orbital, thereby vanishing the shell closure associated with the neutron number $N = 20$. The results are explained by state-of-the-art shell model calculations. Coupled-cluster computations based on effective field theories of the strong nuclear force describe the matter radius of $^{27}$F but are challenged for $^{29}$F.

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S. Bagchi, R. Kanungo, Y. K. Tanaka, H. Geissel, P. Doornenbal, W. Horiuchi, G. Hagen, T. Suzuki, N. Tsunoda, D. S. Ahn, H. Baba, K. Behr, F. Browne, S. Chen, M. L. Cortés, A. Estradé, N. Fukuda, M. Holl, K. Itahashi, N. Iwasa, G. R. Jansen, W. G. Jiang, S. Kaur, A. O. Macchiavelli, S. Y. Matsumoto, S. Momiyama, I. Murray, T. Nakamura, S. J. Novario, H. J. Ong, T. Otsuka, T. Papenbrock, S. Paschalis, A. Prochazka, C. Scheidenberger, P. Schrock, Y. Shimizu, D. Steppenbeck, H. Sakurai, D. Suzuki, H. Suzuki, M. Takechi, H. Takeda, S. Takeuchi, R. Taniuchi, K. Wimmer, K. Yoshida. 2020-05-19. A two-neutron halo is unveiled in $^{29}$F. https://doi.org/10.1103/physrevlett.124.222504

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