Photoexcitation of the stable tl isotopes below the neutron separation energy
Although the systematics of the Pygmy Dipole Resonance was established in several stable even-even nuclei, the collectivity of this mode, explained in a macroscopic picture as an oscillation of a neutron skin against an isospin symmetric proton-neutron core, is still not well understood. In order to guide the theoretical models, we investigated the heavy odd mass, stable isotopes 203;205Tl using unpolarized bremsstrahlung photon beams at the S-DALINAC facility at TU Darmstadt. The NRF experiments were complemented by measurements at the High Intensity -ray Source (HIS) at the Triangle Universities Nuclear Laboratory (TUNL) in Durham, NC, USA, with a fully linearly polarized quasi-monoenergetic photon beam. Between 4 and 7 MeV, a concentration of dipole strength is observed in the odd-mass nuclide 205Tl. For the 203Tl isotope, two ground-state transitions around 5 MeV could be resolved in the spectra. In this report, the obtained results will be presented. The results for the proton-odd nuclide 205Tl will be compared to the ones for the neighbouring even-even nucleus 206Pb.
Benouaret, N; Beller, J; Isaak, J; Kelley, JH; Pai, H; Pietralla, N; Ponomarev, VY; Raut, T; Romig, C; Rusev, G; Savran, D; Scheck, M; Schnorrenberger, L; Sonnabend, K; Tonchev, AP; Tornow, W; Weller, HR; Zweidinger, M
Volume / Issue
Start / End Page
International Standard Serial Number (ISSN)
Digital Object Identifier (DOI)