646 research outputs found
Study of the transition from pairing vibrational to pairing rotational regimes between magic numbers N=50 and N=82, with two-nucleon transfer
Absolute values of two-particle transfer cross sections along the Sn-isotopic
chain from closed shell to closed shell (100Sn,132Sn) are calculated taking
properly into account nuclear correlations, as well as the successive,
simultaneous and non-orthogonality contributions to the differential cross
sections. The results are compared with systematic, homogeneous bombarding
conditions (p, t) data. The observed agreement, almost within statistical
errors and without free parameters, testify to the fact that theory is able to
be quantitative in its predictions
On globally defined semianalytic sets
In this work we present the concept of -semianalytic subset of a real
analytic manifold and more generally of a real analytic space. -semianalytic
sets can be understood as the natural generalization to the semianalytic
setting of global analytic sets introduced by Cartan (-analytic sets for
short). More precisely is a -semianalytic subset of a real analytic
space if each point of has a neighborhood such
that is a finite boolean combinations of global analytic equalities
and strict inequalities on . By means of paracompactness -semianalytic
sets are the locally finite unions of finite boolean combinations of global
analytic equalities and strict inequalities on .
The family of -semianalytic sets is closed under the same operations as
the family of semianalytic sets: locally finite unions and intersections,
complement, closure, interior, connected components, inverse images under
analytic maps, sets of points of dimension , etc. although they are defined
involving only global analytic functions. In addition, we characterize
subanalytic sets as the images under proper analytic maps of -semianalytic
sets.
We prove also that the image of a -semianalytic set under a proper
holomorphic map between Stein spaces is again a -semianalytic set. The
previous result allows us to understand better the structure of the set
of points of non-coherence of a -analytic subset of a real analytic
manifold . We provide a global geometric-topological description of
inspired by the corresponding local one for analytic sets due to
Tancredi-Tognoli (1980), which requires complex analytic normalization. As a
consequence it holds that is a -semianalytic set of dimension
.Comment: 32 pages, 3 figure
Direct observation of the glue pairing the halo of the nucleus 11Li
With the help of a unified description of the nuclear structure and of the
direct reaction mechanism we show that a recent 1H(11Li,9Li)3H experiment
provides, for the first time in nuclear physics, direct evidence of phonon
mediated pairing.Comment: 9 pages, 4 figures. Major change
Structure and reactions of 11Be: many-body basis for single-neutron halo
The exotic nucleus 11Be has been extensively studied and much experimental
information is available on the structure of this system. Treating, within the
framework of empirically renormalised nuclear field theory in both
configuration and 3D-space, the mixing of bound and continuum single-particle
states through the coupling to collective particle-hole (p,h) and pairing
vibrations of the 10Be core, as well as Pauli principle acting not only between
the particles explicitly considered and those participating in the collective
states, but also between fermions involved in two-phonon virtual states it is
possible, for the first time, to simultaneously and quantitatively account for
the energies of the 1/2+,1/2- low-lying states, the centroid and line shape of
the 5/2+ resonance, the one-nucleon stripping and pickup absolute differential
cross sections involving 11Be as either target or residual nucleus, and the
dipole transitions connecting the 1/2+ and 1/2- parity inverted levels as well
as the charge radius, thus providing a unified and exhaustive characterisation
of the many-body effects which are at the basis of this paradigmatic
one-neutron halo system.Comment: Supplemental materials include
Characterization of vorticity in pygmy resonances and soft-dipole modes with two-nucleon transfer reactions
The properties of the two-quasiparticle-like soft E1-modes and PDR have been
and are systematically studied with the help of inelastic and electromagnetic
experiments which essentially probe the particle-hole components of these
vibrations. It is shown that further insight in their characterisation can be
achieved with the help of two-nucleon transferreactions, in particular
concerning the particle-particle components of the modes, in terms of absolute
differential cross sections which take properly into account successive and
simultaneous transfer mechanisms corrected for non-orthogonality, able to
reproduce the experimental findings at the 10% level. The process
LiLi(1) is discussed, and absolute cross sections
predicted.Comment: Typo corrected with respect to previous versio
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