Göttingen 1997 – scientific programme
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HK: Hadronen und Kerne
HK 13: Kernspektroskopie, leichte Kerne I
HK 13.5: Talk
Monday, March 24, 1997, 18:15–18:30, HS E
New region of deformation: the neutron-rich sulfur isotopes — •M. Hellström1, H. Scheit2, T. Glasmacher2, B. A. Brown2, J. A. Brown2, P. D. Cottle3, P. G. Hansen2, R. Harkewicz2, R. W. Ibbotson2, J. K. Jewell3, K. Kemper3, D. J. Morrissey2, M. Steiner2, P. Thirolf2, and M. Thoennessen2 — 1Gesellschaft für Schwerionenforschung, Darmstadt, Germany — 2National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan, USA — 3Florida State University, Tallahassee, Florida, USA
The energies, lifetimes and B(E2;0g.s.+→ 21+) values of the 21+ states of 38,40,42S and 44,46Ar have been measured at the National Superconducting Cyclotron Laboratory at Michigan State University using intermediate-energy (35-40 A MeV) Coulomb excitation. The nuclei were produced via fragmentation of up to 80 A MeV 48Ca and 40Ar beams from the K1200 cyclotron and isotopically separated using the A1200 projectile fragment separator before interacting with a Au target. Gamma-rays following the excitation of the secondary beams were detected in an array of position-sensitive NaI detectors surrounding the Au target, allowing Doppler-shift correction of the transition energies. The results show that 40,42S have |β2| values around 0.3, indicating the presence of a new region of deformed nuclei near N=28. The data on the 21+ state in 46Ar demonstrate that the N=28 major shell gap persists at Z=18. Both mean field calculations and shell model calculations using empirical interactions can approximately reproduce the behavior of the 21+ states of 40,42S.