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2nd International Conference on Nuclear Physics in Astrophysics, Debrecen : Hongrie
Study of the N = 28 shell closure in the Ar isotopic chain A SPIRAL experiment for nuclear astrophysics
L. Gaudefroy1, O. Sorlin2, D. Beaumel1, Y. Blumenfeld1, Z. Dombrádi, S. Fortier1, S. Franchoo1, M. Gélin2, J. Gibelin1, S. Grévy2, F. Hammache1, F. Ibrahim1, K. Kemper, K. L. Kratz, S. M. Lukyanov, C. Monrozeau1, L. Nalpas3, F. Nowacki4, A. N. Ostrowski, Yu. -E. Penionzhkevich, E. Pollacco3, P. Roussel-Chomaz2, E. Rich1, J. A. Scarpaci1, M.G. Saint Laurent2, T. Rauscher, D. Sohler, M. Stanoiu1, E. Tryggestad1, D. Verney1
SPIRAL Collaboration(s)

The structure of the neutron-rich nucleus $^{47}$Ar has been investigated through the d( $^{46)$Ar, $^{47)$Ar)p transfer reaction. The radioactive beam of $^{46}$Ar at 10A·MeV was provided by the SPIRAL facility at GANIL. The protons corresponding to a neutron pick-up on bound or unbound states mechanism in $^{47}$Ar nuclei were detected at backward angles by the position-sensitive Si array-detector MUST. The transfer-like ejectiles were detected in the SPEG spectrometer. Level scheme, spin assignments and spectroscopic factors have been deduced for $^{47}$Ar and compared to shell model predictions. They suggest a slight erosion of the N = 28 shell gap from the weakening of the spin-orbit interaction arising from the f and p orbitals. These spectroscopic information are subsequently used to infer (n,$\gamma$) reaction rates in the Ar isotopic chain to understand the origin of the $^{48}$Ca/ $^{46}$Ca abnormal isotopic ratio observed in certain inclusions of meteorites.
1 :  IPNO - Institut de Physique Nucléaire d'Orsay
2 :  GANIL - Grand Accélérateur National d'Ions Lourds
3 :  DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
4 :  IReS - Institut de Recherches Subatomiques
Physique/Physique Nucléaire Expérimentale
Spin – parity – and isobaric spin – Spectroscopic factors – Transfer reactions – Nucleosynthesis in novae – supernovae and other explosive environments