196 research outputs found
Microcanonical studies concerning the recent experimental evaluations of the nuclear caloric curve
The microcanonical multifragmentation model from [Al. H. Raduta and Ad. R.
Raduta, Phys. Rev. C 55, 1344 (1997); 56, 2059 (1997); 59, 323 (1999)] is
refined and improved by taking into account the experimental discrete levels
for fragments with and by including the stage of sequential decay of
the primary excited fragments. The caloric curve is reevaluated and the heat
capacity at constant volume curve is represented as a function of excitation
energy and temperature. The sequence of equilibrated sources formed in the
reactions studied by the ALADIN group (Au+Au at 600, 800 and
1000 MeV/nucleon bombarding energy) is deduced by fitting simultaneously the
model predicted mean multiplicity of intermediate mass fragments ()
and charge asymmetry of the two largest fragments () versus bound
charge () on the corresponding experimental data. Calculated HeLi
isotopic temperature curves as a function of the bound charge are compared with
the experimentally deduced ones.Comment: 13 pages, 4 figure
The optical potential of He in the eikonal approximation
The new data of the elastic scattering of He+C at about 40
MeV/nucleon are analyzed in the eikonal approximation. The He+C
phase-shift function is evaluated completely without any {\it ad hoc}
assumption by a Monte Carlo integration, which makes it possible to use a
realistic 6-nucleon wave function for a halo nucleus He. The effect of
the breakup of He on the elastic differential cross sections as well as the
optical potential is studied at different energies from 40 to 800 MeV/nucleon.
PACS number(s): 24.10.-i; 21.60.Ka; 25.60.Bx; 25.10.+s Keywords: Eikonal;
Glauber; Monte Carlo; Halo; BreakupComment: 13 pages, 9 figure
Effective Field Theory and Finite Density Systems
This review gives an overview of effective field theory (EFT) as applied at
finite density, with a focus on nuclear many-body systems. Uniform systems with
short-range interactions illustrate the ingredients and virtues of many-body
EFT and then the varied frontiers of EFT for finite nuclei and nuclear matter
are surveyed.Comment: 27 pages, 5 figure
Effects of deformation in the three-body structure of 11Li
11Li is studied within a three-body model 9Li+n+n where the core is allowed
to be deformed and/or excite. In particular, we include reorientation couplings
and couplings between the two bound states of 9Li. Contrary to the other
examples studied within this model, we find that core excitation does not
affect the structure of 11Li significantly. Reorientation couplings of the
deformed 9Li can change the ground state of 11Li from a predominantly two
neutron s1/2^2 configuration into a p1/2^2. In addition, we see no evidence for
the existence of significant d-wave strength in its ground state, as opposed to
the prediction by shell model. A comparison with shell model is presented.Comment: 13 pages, 9 figure
Energy Dependence of Breakup Cross Sections of Halo Nucleus 8B and Effective Interactions
We study the energy dependence of the cross sections for nucleon removal of
8B projectiles. It is shown that the Glauber model calculations with
nucleon-nucleon t-matrix reproduce well the energy dependence of the breakup
cross sections of 8B. A DWBA model for the breakup cross section is also
proposed and results are compared with those of the Glauber model. We show that
to obtain an agreement between the DWBA calculations, the Glauber formalism,
and the experimental data, it is necessary to modify the energy behavior of the
effective interaction. In particular, the breakup potential has a quite
different energy dependence than the strong absorption potential.Comment: 13 pages, 4 figure
Cross sections for Coulomb and nuclear breakup of three-body halo nuclei
All possible dissociation cross sections for the loosely bound three-body
halo nuclei He (n+n+) and Li (n+n+Li) are computed as
functions of target and beam energy. Both Coulomb and nuclear interactions are
included in the same theoretical framework. The measurements agree with the
calculations for energies above 100 Mev/nucleon. The largest cross sections
correspond to final states with zero or three particles for heavy and with two
neutrons for light targets.Comment: 5 pages, 3 figures, revte
MOMDIS: a Glauber model computer code for knockout reactions
A computer program is described to calculate momentum distributions in
stripping and diffraction dissociation reactions. A Glauber model is used with
the scattering wavefunctions calculated in the eikonal approximation. The
program is appropriate for knockout reactions at intermediate energy collisions
(30 MeV Enucleon MeV). It is particularly useful
for reactions involving unstable nuclear beams, or exotic nuclei (e.g.
neutron-rich nuclei), and studies of single-particle occupancy probabilities
(spectroscopic factors) and other related physical observables. Such studies
are an essential part of the scientific program of radioactive beam facilities,
as in for instance the proposed RIA (Rare Isotope Accelerator) facility in the
US.Comment: 22 pages. Accepted for publication in Computer Physics
Communications. Code available from CPC web sit
Monte Carlo integration in Glauber model analysis of reactions of halo nuclei
Reaction and elastic differential cross sections are calculated for light
nuclei in the framework of the Glauber theory. The optical phase-shift function
is evaluated by Monte Carlo integration. This enables us to use the most
accurate wave functions and calculate the phase-shift functions without
approximation. Examples of proton nucleus (e.g. p-He, p-Li) and
nucleus-nucleus (e.g. HeC) scatterings illustrate the effectiveness
of the method. This approach gives us a possibility of a more stringent
analysis of the high-energy reactions of halo nuclei.Comment: 20 pages, 8 figure
Projectile structure effects in the Coulomb breakup of one-neutron halo nuclei
We investigate the Coulomb breakup of neutron rich nuclei 11Be and
(19,17,15)C within a theory developed in the framework of Distorted Wave Born
Approximation. Finite range effects are included by a local momentum
approximation, which allows incorporation of realistic wave functions for these
nuclei in our calculations. Energy and angular as well as parallel momentum
distributions of the fragments emitted in the breakup of these nuclei on heavy
targets have been calculated using several structure models for their ground
state. Comparison with the available experimental data shows that the results
are selective about the ground state wave function of the projectile. Our
investigations confirm that the nuclei 11Be, 19C and 15C have a one-neutron
halo structure in their ground states. However, for 17C such a structure
appears to be less likely. Calculations performed within our method have also
been compared with those from an adiabatic model and the results are discussed.Comment: Minor corrections in a couple of references, Requires elsart.cls 33
pages including 16 figures, Nucl. Phys. A in Pres
Vortex nucleation as a case study of symmetry breaking in quantum systems
Mean-field methods are a very powerful tool for investigating weakly
interacting many-body systems in many branches of physics. In particular, they
describe with excellent accuracy trapped Bose-Einstein condensates. A generic,
but difficult question concerns the relation between the symmetry properties of
the true many-body state and its mean-field approximation. Here, we address
this question by considering, theoretically, vortex nucleation in a rotating
Bose-Einstein condensate. A slow sweep of the rotation frequency changes the
state of the system from being at rest to the one containing one vortex. Within
the mean-field framework, the jump in symmetry occurs through a turbulent phase
around a certain critical frequency. The exact many-body ground state at the
critical frequency exhibits strong correlations and entanglement. We believe
that this constitutes a paradigm example of symmetry breaking in - or change of
the order parameter of - quantum many-body systems in the course of adiabatic
evolution.Comment: Minor change
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