Helda

Helsingin yliopisto

Helsingfors universitet

University of Helsinki

Browsing by Subject "SHAPE COEXISTENCE"

Now showing items 1-2 of 2

Collectivity in Pb-196,Pb-198 isotopes probed in Coulomb-excitation experiments at REX-ISOLDE

Pakarinen, J.; Grahn, T.; Gaffney, L. P.; Algora, A.; Bauer, C.; Blazhev, A.; Bree, N.; Cocolios, T. E.; De Witte, H.; Diriken, J.; Fernier, P.; K, Hadynska-Kle K.; Herzan, A.; Huyse, M.; Iwanicki, J.; Jakobsson, Ulrika; Jenkins, D.; Kesteloot, N.; Konki, J.; Lannoo, B.; Papadakis, P.; Peura, P.; Rahkila, P.; Rainovski, G.; Rapisarda, E.; Reiter, P.; Sambi, S.; Scheck, M.; Seibeck, B.; Seidlitz, M.; Stora, T.; Van Duppen, P.; Warr, N.; Wenander, F.; Vermeulen, M. J.; Voulot, D.; Wrzosek-Lipska, K.; Zielinska, M. (2017)

The neutron-deficient Pb-196,Pb-198 isotopes have been studied in Coulomb-excitation experiments employing the Miniball gamma-ray spectrometer and radioactive ion beams from the REX-ISOLDE post-accelerator at CERN. The reduced transition probabilities of the first excited 2(+) states in Pb-196 and Pb-198 nuclei have been measured for the first time. Values of B (E2) = 18.2(-4.1)(+4.8) W. u. and B (E2) = 13.1(-3.5)(+4.9) W. u., were obtained, respectively. The experiment sheds light on the development of collectivity when moving from the regime governed by the generalised seniority scheme to a region, where intruding structures, associated with different deformed shapes, start to come down in energy and approach the spherical ground state.
Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes : Coulomb excitation of Hg-182, Hg-184, Hg-186 and Hg-188

Wrzosek-Lipska, K.; Rezynkina, K.; Bree, N.; Zielinska, M.; Gaffney, L. P.; Petts, A.; Andreyev, A.; Bastin, B.; Bender, M.; Blazhev, A.; Bruyneel, B.; Butler, P. A.; Carpenter, M. P.; Cederkall, J.; Clement, E.; Cocolios, T. E.; Deacon, A. N.; Diriken, J.; Ekstrom, A.; Fitzpatrick, C.; Fraile, L. M.; Fransen, Ch.; Freeman, S. J.; Garcia-Ramos, J. E.; Geibel, K.; Gernhauser, R.; Grahn, T.; Guttormsen, M.; Hadinia, B.; Hadynska-Klek, K.; Hass, M.; Heenen, P. -H.; Herzberg, R. -D.; Hess, H.; Heyde, K.; Huyse, M.; Ivanov, O.; Jenkins, D. G.; Julin, R.; Kesteloot, N.; Kroell, Th.; Kruecken, R.; Larsen, A. C.; Lutter, R.; Marley, P.; Napiorkowski, P. J.; Orlandi, R.; Page, R. D.; Pakarinen, J.; Patronis, N.; Peura, P. J.; Piselli, E.; Prochniak, L.; Rahkila, P.; Rapisarda, E.; Reiter, P.; Robinson, A. P.; Scheck, M.; Siem, S.; Chakkal, K. Singh; Smith, J. F.; Srebrny, J.; Stefanescu, I.; Tveten, G. M.; Van Duppen, P.; Van de Walle, J.; Voulot, D.; Warr, N.; Wiens, A.; Wood, J. L. (2019)

The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass 182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of 0 + 1,2, 2(1,2)(+) and 4(1)(+) states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.