[Triumf-seminars] TRIUMF Seminar today at 14:00

[postmaster at admin.triumf.ca]

Date/Time: Thu 2008-04-24 at 14:00

Location:  Auditorium          

Speaker:   Irina Stefanescu (Argonne National Laboratory)

Title:     Coulomb excitation of 68,70Cu with MINIBALL and REX-ISOLDE: first use of postaccelerated isomeric beams for nuclear structure investigations

Abstract: Neutron-rich Cu isotopes (Z=28) provide and excellent means for testing the impact of the N=40 subshell closure on the evolution of collectivity around 68Ni. Recent beta-decay studies and Coulomb excitation experiments with radioactive beams of even-even nuclei showed that the coupling of a few extra particles to the 68Ni core induces large polarization effects. The large collectivity observed experimentally was associated with the weakening of the Z=28 and N=40 gap with increasing the number of g9/2 neutrons, as predicted by Otsuka’s tensor force calculations for this mass-region.

The single-particle and collective properties in the odd-odd 68,70Cu were investigated recently by Coulomb excitation with radioactive beams produced at the ISOLDE facility at CERN. The selective laser ionization of RILIS-ISOLDE allowed for the separation of the isomeric states present at low excitation energies in the two copper isotopes. The isomeric beams obtained this way were postaccelerated by REX-ISOLDE to 2.83 MeV/u. Gamma-rays following the deexcitation of the levels populated by Coulomb excitation were detected with the highly segmented MINIBALL array. I will present the experimental technique and set-up and discuss the results obtained and their impact on the evolution of collectivity in this mass-region.

Stimulants available 15 minutes before the talk.

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