Soumya Bagchi
(GSI Helmholtzzentrum)
With large neutron-to-proton ratios far from the line of stability, nuclei develop exotic structures such as neutron skin and halo. Charge radius which is a fundamental nuclear ground-state property, seems to be changing with the increase of valence neutrons. As an example, the charge radius of $^{11}$Li, where there are two valence neutrons in addition to the core $^{9}$Li nucleus, is larger than that of $^9$Li [1]. Therefore, to understand the structure of neutron-rich nuclei, it is important to know how the proton distribution of a nucleus is affected with large neutron-to-proton ratios. A new tool to determine the point-proton root-mean-square radii in exotic nuclei is to measure the charge-changing cross section. It can be used as a probe to measure the extent of the proton distribution in exotic nuclei through the framework of Glauber model analysis [2] of the reaction. Measurements to determine the charge-changing cross section have been done previously for neutron-rich Li, Be, B and C isotopes. Here, we focus on similar systematic studies for neutron-rich nitrogen isotopes. Charge-changing cross sections of stable $^{14,15}$N isotopes and unstable $^{17-22}$N isotopes on a carbon target at relativistic beam energy of around 900 MeV/u have been measured precisely using the FRS fragment separator at GSI [3]. Neutron halo effects are signaled for $^{22}$N as seen from the increase in the proton and matter radii. The radii indicate an unconventional shell gap for neutron number N = 14. In this presentation, the new data on proton distribution radii of neutron-rich nitrogen isotopes will be discussed along with theoretical predictions.
References
[1] R. Sánchez, et al., Phys. Rev. Lett. 96, 033002 (2006).
[2] Y. Suzuki, et al., Phys. Rev. C 94, 011602(R) (2016).
[3] S. Bagchi et al., accepted in Phys. Lett. B.
Soumya Bagchi
(GSI Helmholtzzentrum)
A Estrade
(Department of Physics, Central Michigan University, Mount Pleasant, MI 48859, USA.)
A Evdokimov
(GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt, Germany)
A Prochazka
(GSI)
B Sitar
(Faculty of Mathematics and Physics, Comenius University, 84215 Bratislava, Slovakia)
Chiara Nociforo
(GSI)
Christoph Scheidenberger
(GSI Helmholtzzentrum fuer Schwerionenforschung GmbH)
Dolores Cortina-Gil
(Universidad Santiago Compostela)
Dr
F Ameil
(GSI)
F Farinon
(GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt, Germany)
G Guastalla
(GSI)
G Hagen
(Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA)
Hans Geissel
(GSI)
Helmut Weick
(GSI, Darmstadt)
Dr
Hui.- Jin Ong
(RCNP, Osaka University)
I Mukha
(GSI)
Iris Dillmann
(TRIUMF)
Isao Tanihata
(RCNP, Osaka Univ. and School of Physics, Beihang Univ)
J Atkinson
(Astronomy and Physics Department, Saint Mary’s University, Halifax, NS B3H 3C3, Canada)
J Kurcewicz
(GSI)
J Tanaka
(RCNP, Osaka University, Mihogaoka, Ibaraki, Osaka 567 0047, Japan)
J Vargas
(Universidad de Santiago de Compostela, E-15706 Santiago de Compostela, Spain)
J. S. Winfield
(GSI)
M Marta
(GSI)
M Mostazo
(Universidad de Santiago de Compostela, E-15706 Santiago de Compostela, Spain)
M Takechi
(Department of Physics, Niigata University, Niigata 950-2181, Japan)
P Strmen
(Faculty of Mathematics and Physics, Comenius University, 84215 Bratislava, Slovakia)
R Janik
(Faculty of Mathematics and Physics, Comenius University, 84215 Bratislava, Slovakia)
R Knöbel
(GSI)
Prof.
Rituparna Kanungo
(Saint Mary's University)
S Kaur
(Astronomy and Physics Department, Saint Mary’s University, Halifax, NS B3H 3C3, Canada)
S. R. Stroberg
(TRIUMF, Vancouver, BC V6T 4A3, Canada)
Dr
Satoru Terashima
(Beihang university)
Stephane Pietri
(GSI)
T. D. Morris
(Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA)
Toshio Suzuki
(Nihon University)
Wataru Horiuchi
(Hokkaido University)
Y Tanaka
(GSI, Germany and Saint Mary's University, Halifax, Canada)
Yassid Ayyad
(USC)
Yuri Litvinov
(GSI Helmholtzzentrum für Schwerionenforschung)
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