3,825 research outputs found
Neutrinoless decay nuclear matrix elements in an isotopic chain
We analyze nuclear matrix elements (NME) of neutrinoless double beta decay
calculated for the Cadmium isotopes. Energy density functional methods
including beyond mean field effects such as symmetry restoration and shape
mixing are used. Strong shell effects are found associated to the underlying
nuclear structure of the initial and final nuclei. Furthermore, we show that
NME for two-neutrino double beta decay evaluated in the closure approximation,
, display a constant proportionality with respect to
the Gamow-Teller part of the neutrinoless NME, . This
opens the possibility of determining the matrix
elements from Gamow-Teller strength functions. Finally, the
interconnected role of deformation, pairing, configuration mixing and shell
effects in the NMEs is discussed
Collective and Single-particle Motion in Beyond Mean Field Approaches
We present a novel nuclear energy density functional method to calculate
spectroscopic properties of atomic nuclei. Intrinsic nuclear quadrupole
deformations and rotational frequencies are considered simultaneously as the
degrees of freedom within a symmetry conserving configuration mixing framework.
The present method allows the study of nuclear states with collective and
single-particle character. We calculate the fascinating structure of the
semi-magic 44S nucleus as a first application of the method, obtaining an
excellent quantitative agreement both with the available experimental data and
with state-of-the-art shell model calculations.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. Let
Systematic study of infrared energy corrections in truncated oscillator spaces
We study the convergence properties of nuclear binding energies and
two-neutron separation energies obtained with self-consistent mean-field
calculations based on the Hartree-Fock-Bogolyubov (HFB) method with Gogny-type
effective interactions. Owing to lack of convergence in a truncated working
basis, we employ and benchmark one of the recently proposed infrared energy
correction techniques to extrapolate our results to the limit of an infinite
model space. We also discuss its applicability to global calculations of
nuclear masses.Comment: 12 pages, 12 figure
Large amplitude pairing fluctuations in atomic nuclei
Pairing fluctuations are self-consistently incorporated on the same footing
as the quadrupole deformations in present state of the art calculations
including particle number and angular momentum conservation as well as
configuration mixing. The approach is complemented by the use of the finite
range density dependent Gogny force which, with a unique source for the
particle-hole and particle-particle interactions, guarantees a self-consistent
interplay in both channels.
We have applied our formalism to study the role of the pairing degree of
freedom in the description of the most relevant observables like spectra,
transition probabilities, separation energies, etc. We find that the inclusion
of pairing fluctuations mostly affects the description of excited states,
depending on the excitation energy and the angular momentum. transition
probabilities experiment rather big changes while 's are less affected.
Genuine pairing vibrations are thoroughly studied with the conclusion that
deformations strongly inhibits their existence. These studies have been
performed for a selection of nuclei: spherical, deformed and with different
degree of collectivity.Comment: 23 pages, 23 Figures, To be published in Phys. Rev.
CLIC Overview
The CLIC study is exploring the scheme for an electronpositron collider with a centre-of-mass energy of 3 TeV in order to make the multi-TeV range accessible for lepton physics. The current goal of the project is to demonstrate the feasibility of the technology by the year 2010. Recently, important progress has been made concerning the high-gradient accelerating structure tests and the experiments with beam in the CLIC test facility, CTF3. On the organizational side, the CLIC international collaborations have significantly gained momentum considerably boosting the CLIC study
Normal form of particle motion under the influence of an AC dipole
AC dipoles in accelerators are used to excite coherent betatron oscillations at a drive frequency close to the tune. These beam oscillations may last arbitrarily long and, in principle, there is no significant emittance growth if the AC dipole is adiabatically turned on and off. Therefore the AC dipole seems to be an adequate tool for non-linear diagnostics provided the particle motion is well described in presence of the AC dipole and non-linearities. Normal Forms and Lie algebra are powerful tools to study the non-linear content of an accelerator lattice. In this article a way to obtain the Normal Form of the Hamiltonian of an accelerator with an AC dipole is described. The particle motion to first order in the non-linearities is derived using Lie algebra techniques. The dependence of the Hamiltonian terms on the longitudinal coordinate is studied showing that they vary differently depending on the AC dipole parameters. The relation is given between the lines of the Fourier spectrum of the turn-by-turn motion and the Hamiltonian terms
Triaxial Angular Momentum Projection and Configuration Mixing calculations with the Gogny force
We present the first implementation in the plane of the
generator coordinate method with full triaxial angular momentum and particle
number projected wave functions using the Gogny force. Technical details about
the performance of the method and the convergence of the results both in the
symmetry restoration and the configuration mixing parts are discussed in
detail. We apply the method to the study of Mg, the calculated energies
of excited states as well as the transition probabilities are compared to the
available experimental data showing a good overall agreement. In addition, we
present the RVAMPIR approach which provides a good description of the ground
and gamma bands in the absence of strong mixing.Comment: 40 pages,14 figure
Una articulación metodológica: desde textos del Socio-analisis, I(A)P, F. Praxis, Evelyn F. Keller, Boaventura S. Santos, etc.
This text makes a review, following the contributions of the last decades, from different theoretical currents and practices that make the bases for participative methodologies. It revise texts from socioanalytic, participative investigation action, philosophy of praxis, a debate between constructionisms, aportations from ecofeminism, from ecology of knowledge, etc. and articulate many of this positions in a explicative diagram (of 12 positions) who try to make a differentiation and relation between practice and theory proposition showed in this pages
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