Mean-field studies of time reversal breaking states in super-heavy nuclei with the Gogny force

Recent progress on the description of time reversal breaking (odd mass and multi-quasiparticle excitation) states in super-heavy nuclei within a mean field framework and using several flavors of the Gogny interaction is reported. The study includes ground and excited states in selected odd mass isotopes ofnobelium and mendelevium as well as high K isomeric states in 254No. These are two and four-quasiparticle excitations that are treated in the same self-consistent HFB plus blocking framework as the odd mass statesThis work has been supported in part by the MINECO (Spain) grants Nos. FPA2012-34694 and FIS2012-34479, and by the Consolider-Ingenio 2010 program MULTIDARK CSD2009-0006

Evidence for a smooth onset of deformation in the neutron-rich Kr isotopes

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMThe neutron-rich nuclei 94,96Kr were studied via projectile Coulomb excitation at the REX-ISOLDE facility at CERN. Level energies of the first excited 2+ states and their absolute E2 transition strengths to the ground state are determined and discussed in the context of the E(21+) and B(E2; 21+ → 01+) systematics of the krypton chain. Contrary to previously published results no sudden onset of deformation is observed. This experimental result is supported by a new proton-neutron interacting boson model calculation based on the constrained Hartree-Fock-Bogoliubov approach using the microscopic Gogny-D1M energy density functionalThis work was supported by the BMBF under Contracts No. 06KY9136 and No. 06MT238, by ENSAR, by the DFG Cluster of Excellence Origin and Structure of the Universe, and by the grant-in-aid for scientific research for JSPS Fellows (Grant No. 217368). One of the authors (J. D.) would like to acknowledge the support of FWO-Vlaanderen (Belgium

Cluster radioactivity in superheavy nuclei

Cluster radioactivity is an exotic nuclear decay observed in actinides where a light nucleus is emitted while the remaining heavy mass residue is the doubly magic Pb208 or a nucleus in its neighborhood. We have investigated this type of decay in heavier nuclei up to Lv (Z=116) within a microscopic theory. It has been found that the cluster radioactivity known in the light actinides may become the dominant decay channel in some superheavy nuclei. This superasymmetric fission channel is distinct from typical asymmetric fission in actinides. We predict a sharp fission fragment mass distribution with the heavy fragment close to Pb208.This work was partly supported by the Polish National Science Centre under Contracts No. 2016/21/B/ST2/01227 and No. 2017/24/T/ST2/00396. The work of L.M.R. was supported by Spanish Grants No. FPA2015-65929-P MINECO and No. FIS2015-63770-P MINEC

Do nuclei go pear-shaped? Coulomb excitation 220Rn and 224Ra at REXISOLDE (CERN)

Artículo escrito por muchos autores, sólo se referencian el primero, los autores que firman como Universidad Autónoma de Madrid y el grupo de colaboración en el caso de que aparezca en el artículoThe IS475 collaboration conducted Coulomb-excitation experiments with post-accelerated radioactive 220Rn and 224Ra beams at the REX-ISOLDE facility. The beam particles (Ebeam: 2.83 MeV/u) were Coulomb excited using 60Ni, 114Cd, and 120Sn scattering targets. De-excitation γ-rays were detected employing the Miniball array and scattered particles were detected in a silicon detector. Exploiting the Coulomb-excitation code GOSIA for each nucleus several matrix elements could be obtained from the measured γ-ray yields. The extracted {3-∥E3∥0+} matrix element allows for the conclusion that, while 220Rn represents an octupole vibrational system, 224Ra has already substantial octupole correlations in its ground state. This finding has implications for the search of CP-violating Schiff moments in the atomic systems of the adjacent odd-mass nucleiThis work was supported by the following Research Councils: STFC (UK), BMBF (Germany; 05P12RDCIA, 06DA9036I, 06KY9136I and 06KY205I), HIC for FAIR (Germany), FWO-Vlaanderen (Belgium), Belgian Science Policy Office (IAP-BriX network P7/12), Academy of Finland (contract no. 131665), DOE (US; DE-AC52-07NA27344 and DEFG02- 04ER41331), NSF (US), MICINN (Spain; FPA2009-08958 and FIS2009-07277), Consolider-Ingenio 2010 Programmes (Spain; CPAN CSD2007-00042 and MULTIDARK CSD2009-00064), Polish Ministry for Science and Higher Education (grant no. 589/N-G-POOL/2009/0), EC via I3-EURONS (FP6 contract no. RII3-CT-2004-506065), MC Fellowship scheme (FP7 contract PIEF-GA-2008-219175) and IAENSAR (FP7 contract 262010

New Gogny interaction suitable for astrophysical applications

The D1 family of parametrizations of the Gogny interaction commonly suffers from a rather soft neutron matter equation of state that leads to maximal masses of neutron stars well below the observational value of two solar masses. We propose a reparametrization scheme that preserves the good properties of the Gogny force but allows one to tune the density dependence of the symmetry energy, which, in turn, modifies the predictions for the maximum stellar mass. The scheme works well for D1M, and leads to a new parameter set, dubbed D1M⁎. In the neutron-star domain, D1M⁎predicts a maximal mass of two solar masses and global properties of the star in harmony with those obtained with the SLy4 Skyrme interaction. By means of a set of selected calculations in finite nuclei, we check that D1M⁎performs comparably well to D1M in several aspects of nuclear structure in nucleiThe work of LMR was supported by Spanish Ministry of Economy and Competitiveness (MINECO) Grants No.FPA2015-65929-P and FIS2015-63770-P. C.G., M.C., and X.V. were partially sup-ported by Grant FIS2014-54672-P from MINECO and FEDER, Grant 2014SGR-401 from Generalitat de Catalunya, and Project MDM-2014-0369 of ICCUB (Unidad de Excelencia María de Maeztu) from MINECO. C.G. also acknowledges Grant BES-2015-074210 from MINEC

Separable approximation to two-body matrix elements

Two-body matrix elements of arbitrary local interactions are written as the sum of separable terms in a way that is well suited for the exchange and pairing channels present in mean-field calculations. The expansion relies on the transformation to center of mass and relative coordinate (in the spirit of Talmi's method) and therefore it is only useful (finite number of expansion terms) for harmonic oscillator single particle states. The converge of the expansion with the number of terms retained is studied for a Gaussian two body interaction. The limit of a contact (delta) force is also considered. Ways to handle the general case are also discussed.Comment: 10 pages, 5 figures (for high resolution versions of some of the figures contact the author