Backbending in 50Cr

The collective yrast band and the high spin states of the nucleus 50Cr are studied using the spherical shell model and the HFB method. The two descriptions lead to nearly the same values for the relevant observables. A first backbending is predicted at I=10\hbar corresponding to a collective to non-collective transition. At I=16\hbar a second backbending occurs, associated to a configuration change that can also be interpreted as an spherical to triaxial transition.Comment: ReVTeX v 3.0 epsf.sty, 5 pages, 5 figures included. Full Postscript version available at http://www.ft.uam.es/~gabriel/Cr50art.ps.g

Isobaric multiplet yrast energies and isospin non-conserving forces

The isovector and isotensor energy differences between yrast states of isobaric multiplets in the lower half of the $pf$ region are quantitatively reproduced in a shell model context. The isospin non-conserving nuclear interactions are found to be at least as important as the Coulomb potential. Their isovector and isotensor channels are dominated by J=2 and J=0 pairing terms, respectively. The results are sensitive to the radii of the states, whose evolution along the yrast band can be accurately followed.Comment: 4 pages, 4 figures. Superseeds second part of nucl-th/010404

Spur Pruning Leaving One Bud is an Interesting Viticultural Strategy to Control Bud Acrotony in Bolivian Vineyards

Bolivian viticulture is mostly found in the Central Valley of Tarija, which is characterised by a subtropicalclimate with high thermal oscillation in winter that results in low accumulation of chilling units. Suchclimatic conditions accentuate acrotony in vines, which affect budburst uniformity and, consequently,yield and bunch quality at harvest. The aim of this study was to evaluate the effect of different spur pruningstrategies on the percentage of budburst and fertility of buds located in different nodal positions in bothwine and table grape varieties growing in the Central Valley of Tarija. The results show that allocatingspurs with fewer buds improved the budding of most of the distal buds studied. This was noted in boththe wine and table grape cultivars, but mostly in the latter. Spur pruning leaving one bud improved thepercentage of budburst and the fertility of the distal buds in Cabernet Sauvignon, Cardinal and Ribier,thereby preventing bud acrotony, compared to spur pruning leaving two buds. Spur pruning leaving twobuds improved the budburst of latent buds in Cabernet Sauvignon. Therefore, to avoid acrotony patterns,viticulturists should perform pruning leaving one bud

Fission properties for r-process nuclei

We present a systematics of fission barriers and fission lifetimes for the whole landscape of super-heavy elements (SHE), i.e. nuclei with Z>100. The fission lifetimes are also compared with the alpha-decay half-lives. The survey is based on a self-consistent description in terms of the Skyrme-Hartree-Fock (SHF) approach. Results for various different SHF parameterizations are compared to explore the robustness of the predictions. The fission path is computed by quadrupole constrained SHF. The computation of fission lifetimes takes care of the crucial ingredients of the large-amplitude collective dynamics along the fission path, as self-consistent collective mass and proper quantum corrections. We discuss the different topologies of fission landscapes which occur in the realm of SHE (symmetric versus asymmetric fission, regions of triaxial fission, bi-modal fission, and the impact of asymmetric ground states). The explored region is extended deep into the regime of very neutron-rich isotopes as they are expected to be produced in the astrophysical r process

Full 0ℏω0\hbar\omega shell model calculation of the binding energies of the 1f7/21f_{7/2} nuclei

Binding energies and other global properties of nuclei in the middle of the $pf$ shell, such as M1, E2 and Gamow-Teller sum rules, have been obtained using a new Shell Model code (NATHAN) written in quasi-spin formalism and using a $j-j$-coupled basis. An extensive comparison is made with the recently available Shell Model Monte Carlo results using the effective interaction KB3. The binding energies for -nearly- all the $1f_{7/2}$ nuclei are compared with the measured (and extrapolated) results.Comment: 7 page

The Innermost Ejecta of Core Collapse Supernovae

We ensure successful explosions (of otherwise non-explosive models) by enhancing the neutrino luminosity via reducing the neutrino scattering cross sections or by increasing the heating efficiency via enhancing the neutrino absorption cross sections in the heating region. Our investigations show that the resulting electron fraction Ye in the innermost ejecta is close to 0.5, in some areas even exceeding 0.5. We present the effects of the resulting values for Ye on the nucleosynthesis yields of the innermost zones of core collapse supernovae.Comment: 4pages, 2figures; contribution to Nuclei In The Cosmos VIII, to appear in Nucl. Phys.

Spatially inhomogeneous condensate in asymmetric nuclear matter

We study the isospin singlet pairing in asymmetric nuclear matter with nonzero total momentum of the condensate Cooper pairs. The quasiparticle excitation spectrum is fourfold split compared to the usual BCS spectrum of the symmetric, homogeneous matter. A twofold splitting of the spectrum into separate branches is due to the finite momentum of the condensate, the isospin asymmetry, or the finite quasiparticle lifetime. The coupling of the isospin singlet and triplet paired states leads to further twofold splitting of each of these branches. We solve the gap equation numerically in the isospin singlet channel in the case where the pairing in the isospin triplet channel is neglected and find nontrivial solutions with finite total momentum of the pairs. The corresponding phase assumes a periodic spatial structure which carries a isospin density wave at constant total number of particles. The phase transition from the BCS to the inhomogeneous superconducting phase is found to be first order and occurs when the density asymmetry is increased above 0.25. The transition from the inhomogeneous superconducting to the unpaired normal state is second order. The maximal values of the critical total momentum (in units of the Fermi momentum) and the critical density asymmetry at which condensate disappears are $P_c/p_F = 0.3$ and $\alpha_c = 0.41$. The possible spatial forms of the ground state of the inhomogeneous superconducting phase are briefly discussed.Comment: 13 pages, including 3 figues, uses RevTeX; minor corrections, PRC in pres

Electron capture on iron group nuclei

We present Gamow-Teller strength distributions from shell model Monte Carlo studies of fp-shell nuclei that may play an important role in the pre-collapse evolution of supernovae. We then use these strength distributions to calculate the electron-capture cross sections and rates in the zero-momentum transfer limit. We also discuss the thermal behavior of the cross sections. We find large differences in these cross sections and rates when compared to the naive single-particle estimates. These differences need to be taken into account for improved modeling of the early stages of type II supernova evolution