München 2006 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 49: Kernphysik/Spektroskopie

HK 49.4: Talk

Thursday, March 23, 2006, 18:15–18:30, C

Dipole response of neutron-rich even-odd nuclei around ¹³²Sn — •Adam Klimkiewicz — Gesellschaft für Schwerionenforschung (GSI), D-64291 Darmstadt — Instytut Fizyki, Uniwersytet Jagielloński, PL-30-059 Kraków, Poland

The unstable neutron-rich nuclei ^129−133Sn and ^133,134Sb isotopes were produced by in-flight fission of a primary ²³⁸U beam (E_kin≈500 MeV/u) at GSI,Darmstadt, and were separated in flight from other reaction products by means of the fragment separator FRS. Coulomb excitation of these isotopes in a Pb target was measured at the LAND setup and the dipole strength distribution above the neutron separation threshold was deduced. Below the giant dipole resonance at around E^*≈15 MeV, a sizeable fraction of dipole strength is found in all isotopes. In case of the even-even ^130,132Sn isotopes, this strength was discussed in terms of a pygmy resonance in an earlier publication [1]. Dipole strength right at the neutron separation threshold appears in the isotopes with an odd neutron number being related to the unpaired neutron. An attempt was made to analyze this strength within the direct breakup model [2,3] which describes non-resonant dipole transitions into the continuum.

[1] P.Adrich et al.,Phys. Rev. Lett.95(2005)132501

[2] R.Palit et al.,Nucl. Phys. A731(2004)235-248

[3] S.Typel,G.Baur, Phys. Rev. C64(2001)024601