[Triumf-seminars] TRIUMF Seminar today at 11:00

[postmaster at admin.triumf.ca]

Date/Time: Thu 2010-01-14 at 11:00

Location:  Auditorium          

Speaker:   Jörg Leske (Technical University of Darmstadt)

Title:     Isospin structure of short-lived excited nuclear states from lifetimes and magnetic moment measurements

Abstract: In the vicinity of the Z = 50 and N = 82 magic shell closures unexpected findings in the behaviour of the electric quadrupole transition probabilities of excited nuclear states, e.g. the surplus of B(E2) strengths in neutron deficient Sn isotopes or the surprisingly small B(E2, 0+_1 -> 2+_1 ) in 136Te, have triggered many theoretical investigations and further experiments. However, model predictions could only partially explain the observed behaviour and the isospin structure of the excitations in the nuclear valence shell is discussed controversially, e.g. in 136Te where results from calculations differ significantly. Due to their unique sensitivity to the different role of protons and neutrons in the structure of nuclei and their excited states magnetic dipole moments are along with lifetime information indispensable tools for nuclear structure research. For short lifetimes in the range of ~100 femtoseconds to 10 picoseconds the measurement of magnetic moments is challenging and solely the technique of Transient Magnetic Fields (TF) and Recoil-In-Vacuum (RIV) can be applied. Lifetimes and magnetic moments grant access to the missing experimental information and provide new insights into the nuclear structure phenomena mentioned above. Experimental aspects and developments will be presented and achievements and results from stable as well as radioactive beam experiments will be discussed for the mass region around A = 40 and for Sn, Xe, Te and Ba isotopes together with their impact on partially very basic and fundamental concepts as seniority.

Stimulants available 15 minutes before the talk.

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