# Vanishing N=20 Shell Gap: Study of Excited States in $^{27,28}$Ne

Abstract : This Letter reports on the 1H(28Ne,28Ne) and 1H(28Ne,27Ne) reactions studied at intermediate energy using a liquid hydrogen target. From the cross section populating the first 2+ excited state of 28Ne, and using the previously determined B(E2) value, the neutron quadrupole transition matrix element has been calculated to be Mn=13.8±3.7 fm2. In the neutron knockout reaction, two low-lying excited states were populated in 27Ne. Only one of them can be interpreted by the sd shell model while the additional state may intrude from the fp shell. These experimental observations are consistent with the presence of fp shell configurations at low excitation energy in 27,28Ne nuclei caused by a vanishing N=20 shell gap at Z=10.
Document type :
Journal articles

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Submitted on : Tuesday, December 5, 2006 - 9:37:35 AM
Last modification on : Wednesday, September 16, 2020 - 4:07:36 PM

### Citation

Zs. Dombrádi, Z. Elekes, A. Saito, N. Aoi, H. Baba, et al.. Vanishing N=20 Shell Gap: Study of Excited States in $^{27,28}$Ne. Physical Review Letters, American Physical Society, 2006, 96, pp.182501. ⟨10.1103/PhysRevLett.96.182501⟩. ⟨in2p3-00118340⟩

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