24 research outputs found
Phase space factors and half-life predictions for Majoron emitting decay
A complete calculation of phase space factors (PSF) for Majoron emitting
decay modes is presented. The calculation makes use of
exact Dirac wave functions with finite nuclear size and electron screening and
includes life-times, single electron spectra, summed electron spectra, and
angular electron correlations. Combining these results with recent interacting
boson nuclear matrix elements (NME) we make half-life predictions for the the
ordinary Majoron decay (spectral index =1). Furthermore, comparing
theoretical predictions with the obtained experimental lower bounds for this
decay mode we are able to set limits on the effective Majoron-neutrino coupling
constant
Occupation probabilities of single particle levels using the microscopic interacting boson model: Application to some nuclei of interest in neutrinoless double- β
We have developed a new method to calculate the occupancies of single particle levels in atomic nuclei.
This method has been developed in the context of the microscopic interacting boson model, in which neutron
and proton degrees of freedom are treated explicitly. The energies of the single particle levels constitute a very
important input for the calculation of the occupancies in this method. In principle these energies can be considered
as input parameters that can be fitted to reproduce the experimental occupancies. Instead of fitting, in this study
we have extracted the single particle energies from experimental data on nuclei with a particle more or one particle
less than a shell closure. We provide the sets of these single particle energies suitable for several major shells and
apply our method to calculate the occupancies of several nuclei of interest in neutrinoless double-β decay using
these sets. Our results are compared with other theoretical calculations and experimental occupancies, when
available.peerReviewe
New supersymmetric quartet of nuclei in the A=190 mass region
We present evidence for a new supersymmetric quartet in the A=190 region of
the nuclear mass table. New experimental information on transfer and neutron
capture reactions to the odd-odd nucleaus 194 Ir strongly suggests the
existence of a new supersymmetric quartet, consisting of the 192,193 Os and
193,194 Ir nuclei. We make explicit predictions for the odd-neutron nucleus 193
Os, and suggest that its spectroscopic properties be measured in dedicated
experiments.Comment: 5 pages, 4 figures, updated figures and revised text, Physical Review
C, Rapid Communication, in pres
Relationship between X(5)-models and the interacting boson model
The connections between the X(5)-models (the original X(5) using an infinite
square well, X(5)-, X(5)-, X(5)-, and
X(5)-), based on particular solutions of the geometrical Bohr
Hamiltonian with harmonic potential in the degree of freedom, and the
interacting boson model (IBM) are explored. This work is the natural extension
of the work presented in [1] for the E(5)-models. For that purpose, a quite
general one- and two-body IBM Hamiltonian is used and a numerical fit to the
different X(5)-models energies is performed, later on the obtained wave
functions are used to calculate B(E2) transition rates. It is shown that within
the IBM one can reproduce well the results for energies and B(E2) transition
rates obtained with all these X(5)-models, although the agreement is not so
impressive as for the E(5)-models. From the fitted IBM parameters the
corresponding energy surface can be extracted and it is obtained that,
surprisingly, only the X(5) case corresponds in the moderate large N limit to
an energy surface very close to the one expected for a critical point, while
the rest of models seat a little farther.Comment: Accepted in Physical Review