Mainz 2012 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 32: Struktur und Dynamik von Kernen

HK 32.9: Vortrag

Mittwoch, 21. März 2012, 18:45–19:00, RW 3

Role of the momentum transfer in the quenching of the Gamow-Teller strength — •Tomislav Marketin^1,2, Gabriel Martínez-Pinedo¹, Nils Paar², and Dario Vretenar² — ¹Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany — ²Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia

A fully consistent calculation of the Gamow-Teller strength is presented, based on a microscopic theoretical framework. Nuclear ground state is determined using the relativistic Hartree-Bogoliubov (RHB) model with density dependent meson-nucleon coupling constants, and transition rates are calculated via proton-neutron relativistic quasiparticle RPA using the same interaction as in the RHB equations.

The (p,n) probe has a similar spin-isospin operator structure to the Gamow-Teller (GT) operator. However, they become comparable only if the GT cross section is measured at a very small momentum transfer q. At higher momentum transfer the isovector spin monopole (IVSM) mode occurs, with the r²στ transition operator. Unlike the Gamow-Teller operator which excites only the 0ℏ ω transitions, the isovector spin monopole operator can also excite 2ℏ ω transitions and can change the strength distribution at high excitation energies. We explore the strength beyond the resonance, examine the effect of momentum transfer on the total strength and compare the results with recent measurements.