Broda, R. et al, & Gadea, A. (2010). Proton-hole states in the N=30 neutron-rich isotope K-49. Phys. Rev. C, 82(3), 034319–7pp.
Abstract: Excited states in the N = 30 neutron-rich isotope K-49 have been studied using multinucleon transfer reactions with thin targets and the PRISMA-CLARA spectrometer combined with thick-target gamma-coincidence data from Gammasphere. The d(3/2) proton-hole state is located 92 keV above the s(1/2) ground state, and the proton-particle f(7/2) state is suggested at 2104 keV. Three other levels are established as involving the coupling to 2(+) of two neutrons above the N = 28 shell. The measured or estimated lifetimes served to reinforce the interpretation of the observed level structure, which is found to be in satisfactory agreement with shell-model calculations.
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Bizzeti, P. G. et al, & Gadea, A. (2010). Transition probabilities in the X(5) candidate Ba-122. Phys. Rev. C, 82(5), 054311–10pp.
Abstract: To investigate the possible X(5) character of Ba-122, suggested by the ground-state band energy pattern, the lifetimes of the lowest yrast states of Ba-122 have been measured, via the recoil distance Doppler-shift method. The relevant levels have been populated by using the Cd-108(O-16,2n)Ba-122 and the Sn-112(C-13, 3n)Ba-122 reactions. The B(E2) values deduced in the present work are compared to the predictions of the X(5) model and to calculations performed in the framework of the IBA-1 and IBA-2 models.
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Ljungvall, J. et al, & Gadea, A. (2010). Onset of collectivity in neutron-rich Fe isotopes: Toward a new island of inversion? Phys. Rev. C, 81(6), 061301–4pp.
Abstract: The lifetimes of the first excited 2(+) states in Fe-62 and Fe-64 have been measured for the first time using the recoil-distance Doppler shift method after multinucleon transfer reactions in inverse kinematics. A sudden increase of collectivity from Fe-62 to Fe-64 is observed. The experimental results are compared with new large-scale shell-model calculations and Hartree-Fock-Bogolyubov-based configuration-mixing calculations using the Gogny D1S interaction. The results give a deeper understanding of the mechanism leading to an onset of collectivity near Ni-68, which is compared with the situation in the so-called island of inversion around Mg-32.
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Caballero, L., Rubio, B., Kleinheinz, P., Yates, S. W., Algora, A., Dewald, A., et al. (2010). Two-phonon octupole excitation in Gd-146. Phys. Rev. C, 81(3), 031301–4pp.
Abstract: Based on experimental evidence from the Sm-144(alpha,2n) reaction, the 3484.7- keV 6(+) state in Gd-146 is identified as the highest-spin member of the 3(-) circle times 3(-) two-phonon octupole quartet. A previously unknown gamma line of 1905.8 keV and E3 character feeding the 3(-) octupole state has been observed. These results represent the first observation of a 6(+) -> 3(-) -> 0(+) cascade of two E3 transitions in an even-even nucleus and provide strong support for the interpretation of the 6(+) state as a two-phonon octupole excitation.
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Soderstrom, P. A. et al, Algora, A., & Gadea, A. (2010). Spectroscopy of neutron-rich Dy-168,Dy-170: Yrast band evolution close to the NpNn valence maximum. Phys. Rev. C, 81(3), 034310–5pp.
Abstract: The yrast sequence of the neutron-rich dysprosium isotope Dy-168 has been studied using multinucleon transfer reactions following collisions between a 460-MeV Se-82 beam and an Er-170 target. The reaction products were identified using the PRISMA magnetic spectrometer and the gamma rays detected using the CLARA HPGe-detector array. The 2(+) and 4(+) members of the previously measured ground-state rotational band of Dy-168 have been confirmed and the yrast band extended up to 10(+). A tentative candidate for the 4(+) -> 2(+) transition in Dy-170 was also identified. The data on these nuclei and on the lighter even-even dysprosium isotopes are interpreted in terms of total Routhian surface calculations and the evolution of collectivity in the vicinity of the proton-neutron valence product maximum is discussed.
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