Neutron skin and signature of the N = 14 shell gap found from measured proton radii of [superscript 17−22] N

Bagchi, Soumya; Kanungo, Rituparna; Horiuchi, W.; Hagen, G.; Morris, T.D.; Stroberg, S.R.; Suzuki, T.; Ameil, F.; Atkinson, Joel; Ayyad, Y.; Cortina-Gil, D.; Dillmann, I.; Estradé, Alfredo; Evdokimov, A.; Farinon, F.; Geissel, H.; Guastalla, G.; Janik, R.; Kaur, Satbir; Knöbel, R.; Kurcewicz, J.; Litvinov, Yu.A.; Marta, M.; Mostazo, M.; Mukha, I.; Nociforo, C.; Ong, H.J.; Pietri, S.; Prochazka, A.; Scheidenberger, C.; Sitar, B.; Strmen, P.; Takechi, M.; Tanaka, J.; Tanaka, Yoshiki K.; Tanihata, I.; Terashima, S.; Vargas, J.; Weick, H.; Winfield, J.S.

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Neutron skin and signature of the N = 14 shell gap found from measured proton radii of [superscript 17−22] N

Bagchi, Soumya; Kanungo, Rituparna; Horiuchi, W.; Hagen, G.; Morris, T.D.; Stroberg, S.R.; Suzuki, T.; Ameil, F.; Atkinson, Joel; Ayyad, Y.; Cortina-Gil, D.; Dillmann, I.; Estradé, Alfredo; Evdokimov, A.; Farinon, F.; Geissel, H.; Guastalla, G.; Janik, R.; Kaur, Satbir; Knöbel, R.; Kurcewicz, J.; Litvinov, Yu.A.; Marta, M.; Mostazo, M.; Mukha, I.; Nociforo, C.; Ong, H.J.; Pietri, S.; Prochazka, A.; Scheidenberger, C.; Sitar, B.; Strmen, P.; Takechi, M.; Tanaka, J.; Tanaka, Yoshiki K.; Tanihata, I.; Terashima, S.; Vargas, J.; Weick, H.; Winfield, J.S.

Date: 2019-01-21

Type: Text

ISSN: 0370-2693

Source:

Physics Letters B 790, 251-256. (2019)

Abstract:

A thick neutron skin emerges from the first determination of root mean square radii of the proton distributions for ¹⁷⁻²²N from charge changing cross section measurements around 900A MeV at GSI. Neutron halo effects are signalled for ²²N from an increase in the proton and matter radii. The radii suggest an unconventional shell gap at N = 14 arising from the attractive proton–neutron tensor interaction, in good agreement with shell model calculations. Ab initio, in-medium similarity re-normalization group, calculations with a state-of-the-art chiral nucleon–nucleon and three-nucleon interaction reproduce well the data approaching the neutron drip-line isotopes but are challenged in explaining the complete isotopic trend of the radii.