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Engineering topics

Sarriguren, P

Publications and source records attributed to Sarriguren, P.

5 records

All sources NASA NTRS DOE OSTI

DOE OSTI2012

Nuclear shape transitions in neutron-rich medium-mass nuclei

We study the isotopic evolution of the ground-state nuclear shapes in neutron-rich Kr, Rb, Sr, Y, Zr, Nb, and Mo isotopic chains. Both even-even and odd-A nuclei are included in the analysis. For the latter we also study the systematics of their one-quasiparticle low-lying configurations. The theoretical approach is based on a selfconsistent Hartree-Fock-Bogoliubov formalism with finite range Gogny energy density functionals. Neutron separation energies, charge radii, and the spin-parity of the ground states are calculated and compared with available data. Shape-transition signatures are identified around N= 60 isotones as discontinuities in both charge radii isotopic shifts and spin-parities of the ground states. The nuclear deformation including triaxiality is shown to play a relevant role in the understanding of the bulk and spectroscopic features of the ground and low-lying one-quasiparticle states.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2011

Weak decay rates for neutron-deficient Kr isotopes relevant for the rp process

Weak interaction rates under stellar density and temperature conditions relevant for the rp process are studied in neutron-deficient Kr isotopes. The nuclear structure part of the problem is described within the deformed Skyrme Hartree-Fock+BCS+QRPA, which reproduces not only the beta-decay half-lives but also the available Gamow-Teller strength distributions, measured under terrestrial conditions. The various sensitivities of the decay rates to both density and temperature are discussed. In particular, we study the contributions coming from excited states in the parent nucleus, which are thermally populated, and the competition between beta-decays and continuum electron captures.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2011

Selected Topics on Nuclear Structure in Electroweak Processes

We study electroweak processes in complex nuclei within the framework of self-consistent mean field theories including pairing and RPA correlations. We review the adiabatic time dependent Hartree-Fock (HF) theory and its ability to simultaneously handle large and small amplitude modes. We apply the formalism to the study of single and double beta decay as normal modes of the system, allowing for collective deformation, using Skyrme density-dependent two-body interactions. We also apply the formalism to the study of parity-violating electron scattering. We highlight nuclear structure issues that are crucial for the correct analysis of these processes, namely neutron densities and spectroscopic factors, whose proper knowledge and interpretation in stable nuclei is required to get reliable predictions on exotic nuclei.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2011

Signatures of structural changes in neutron-rich Sr, Zr and Mo isotopes

The evolution of the ground-state nuclear shapes in neutron-rich Sr, Zr, and Mo isotopes, including both even-even and odd-A nuclei, is discussed within the mean-field approximation based on the Gogny-D1S Gogny Energy Density Functional. Calculations for neutron separation energies and charge radii are presented and compared with available data. A correlation between a shape transition and a discontinuity in those observables is found within our microscopic framework. It is shown that, while in Sr and Zr isotopes the steep behavior observed in the isotopic dependence of the charge radii is a consequence of a sharp prolate-oblate transition, the smooth behavior found in Mo isotopes has its origin in an emergent region of triaxiality.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2011

Surface properties of neutron-rich exotic nuclei: A source for studying the nuclear symmetry energy

We study the correlation between the thickness of the neutron skin in finite nuclei and the nuclear symmetry energy for isotopic chains of even-even Ni, Sn, and Pb nuclei in the framework of the deformed self-consistent mean-field Skyrme HF + BCS method. The symmetry energy, the neutron pressure, and the asymmetric compressibility in finite nuclei are calculated within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy density functional. The mass dependence of the nuclear symmetry energy and the neutron-skin thickness are also studied together with the role of the neutron-proton asymmetry. A correlation between the parameters of the equation of state (symmetry energy and its density slope) and the neutron skin is suggested in the isotopic chains of Ni, Sn, and Pb nuclei.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗