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Phys. Rev. Lett. 80, 2081–2084 (1998)

Quadrupole Collectivity in 32,34,36,38Si and the N = 20 Shell Closure

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R. W. Ibbotson1, T. Glasmacher1,2, B. A. Brown1,2, L. Chen1,2, M. J. Chromik1,*, P. D. Cottle3, M. Fauerbach1,2,†, K. W. Kemper3, D. J. Morrissey1,4, H. Scheit1,2, and M. Thoennessen1,2
1National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824
2Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824
3Department of Physics, Florida State University, Tallahassee, Florida, 32306
4Department of Chemistry, Michigan State University, East Lansing, Michigan 48824

Received 13 August 1997; published in the issue dated 9 March 1998

The β-unstable nuclei 32,34,36,38Si have been produced by projectile fragmentation and studied by in-beam Coulomb excitation. Excited states at 1399±25 keV and 1084±20 keV have been identified for the first time in 36Si and 38Si, respectively, and tentatively assigned Jπ = 2+. The B(E2;01+→21+) values leading to these states and the previously identified 21+ states in 32,34Si have been measured, and are compared to shell model calculations. Our results indicate that the 21+ state in 34Si has a large fp-shell intruder component, and that the 21+ states in the N>20 silicon isotopes can be reproduced assuming an N = 20 shell closure.

© 1998 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.80.2081
DOI:
10.1103/PhysRevLett.80.2081
PACS:
23.20.Js, 21.60.Cs, 25.70.De, 27.30.+t

*Present address: Ludwig Maximilians Universität München, Garching, Germany.

Present address: Department of Physics, Florida State University, Tallahassee, FL 32306.