Experimental evidence for subshell closure in He-8 and indication of a resonant state in He-7 below 1 MeV (Journal article)

Skaza, F./ Lapoux, V./ Keeley, N./ Alamanos, N./ Pollacco, E. C./ Auger, F./ Drouart, A./ Gillibert, A./ Beaumel, D./ Becheva, E./ Blumenfeld, Y./ Delaunay, F./ Giot, L./ Kemper, K. W./ Nalpas, L./ Obertelli, A./ Pakou, A./ Raabe, R./ Roussel-Chomaz, P./ Sida, J. L./ Scarpaci, J. A./ Stepantsov, S./ Wolski, R.

The spectroscopy of the unstable He-8 and unbound He-7 nuclei is investigated via the p(He-8, d) transfer reaction with a 15.7A MeV He-8 beam from the SPIRAL facility. The emitted deuterons were detected by the telescope array MUST. The results are analyzed within the coupled-channels Born approximation framework, and a spectroscopic factor (CS)-S-2=4.4 +/- 1.3 for neutron pickup to the He-7(g.s.) is deduced. This value is consistent with a full p3/2 subshell for He-8. Tentative evidence for the first excited state of He-7 is found at E-*=0.9 +/- 0.5 MeV (width Gamma=1.0 +/- 0.9 MeV). The second one is observed at a position compatible with previous measurements, E-*=2.9 +/- 0.1 MeV. Both are in agreement with previous separate measurements. The reproduction of the first excited state below 1 MeV would be a challenge for the most sophisticated nuclear theories.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών
Keywords: model,scattering,nuclei
URI: https://olympias.lib.uoi.gr/jspui/handle/123456789/16188
ISSN: 0556-2813
Link: <Go to ISI>://000237157300013
Appears in Collections:Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά)

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