136 research outputs found
Critical temperature for the nuclear liquid-gas phase transition (from multifragmentation and fission)
Critical temperature Tc for the nuclear liquid-gas phase transition is
stimated both from the multifragmentation and fission data. In the first
case,the critical temperature is obtained by analysis of the IMF yields in
p(8.1 GeV)+Au collisions within the statistical model of multifragmentation
(SMM). In the second case, the experimental fission probability for excited
188Os is compared with the calculated one with Tc as a free parameter. It is
concluded for both cases that the critical temperature is higher than 16 MeV.Comment: 15 pages, 8 figure
Recoil Studies in the Reaction of 12-C Ions with the Enriched Isotope 118-Sn
The recoil properties of the product nuclei from the interaction of 2.2
GeV/nucleon 12-C ions from Nuclotron of the Laboratory of High Energies (LHE),
Joint Institute for Nuclear Research (JINR) at Dubna with a 118-Sn target have
been studied using catcher foils. The experimental data were analyzed using the
mathematical formalism of the standard two-step vector model. The results for
12-C ions are compared with those for deuterons and protons. Three different
Los Alamos versions of the Quark-Gluon String Model (LAQGSM) were used for
comparison with our experimental data.Comment: 10 pages, 6 figures, submitted to Nucl. Phys.
Measurement of the complete nuclide production and kinetic energies of the system 136Xe + hydrogen at 1 GeV per nucleon
We present an extensive overview of production cross sections and kinetic
energies for the complete set of nuclides formed in the spallation of 136Xe by
protons at the incident energy of 1 GeV per nucleon. The measurement was
performed in inverse kinematics at the FRagment Separator (GSI, Darmstadt).
Slightly below the Businaro-Gallone point, 136Xe is the stable nuclide with the
largest neutron excess. The kinematic data and cross sections collected in this
work for the full nuclide production are a general benchmark for modelling the
spallation process in a neutron-rich nuclear system, where fission is
characterised by predominantly mass-asymmetric splits.Comment: 18 pages, 14 figure
High-resolution velocity measurements on fully identified light nuclides produced in 56Fe + hydrogen and 56Fe + titanium systems
New experimental results on the kinematics and the residue production are
obtained for the interactions of 56Fe projectiles with protons and (nat)Ti
target nuclei, respectively, at theincident energy of 1 A GeV. The
titanium-induced reaction serves as a reference case for multifragmentation.
Already in the proton-induced reaction, the characteristics of the isotopic
cross sections and the shapes of the velocity spectra of light residues
indicate that high thermal energy is deposited in the system during the
collision. In the 56Fe+p system the high excitation seems to favour the onset
of fast break-up decays dominated by very asymmetric partitions of the
disassembling system. This configuration leads to the simultaneous formation of
one or more light fragments together with one heavy residue.Comment: 24 pages, 21 figures, 1 table, this work forms part of the PhD thesis
of P.Napolitani, background information on http://www-w2k.gsi.de/kschmidt
Critical Temperature for the Nuclear Liquid-Gas Phase Transition
The charge distribution of the intermediate mass fragments produced in p (8.1
GeV) + Au collisions is analyzed in the framework of the statistical
multifragmentation model with the critical temperature for the nuclear
liquid-gas phase transition as a free parameter. It is found that
MeV (90% CL).Comment: 4 pages, 3 figures, published in Phys. Rev.
On the solution of a supersymmetric model of correlated electrons
We consider the exact solution of a model of correlated electrons based on
the superalgebra . The corresponding Bethe ansatz equations have an
interesting form. We derive an expression for the ground state energy at half
filling. We also present the eigenvalue of the transfer matrix commuting with
the Hamiltonian.Comment: Palin latex , 8 page
Lattice fermion models with supersymmetry
We investigate a family of lattice models with manifest N=2 supersymmetry.
The models describe fermions on a 1D lattice, subject to the constraint that no
more than k consecutive lattice sites may be occupied. We discuss the special
properties arising from the supersymmetry, and present Bethe ansatz solutions
of the simplest models. We display the connections of the k=1 model with the
spin-1/2 antiferromagnetic XXZ chain at \Delta=-1/2, and the k=2 model with
both the su(2|1)-symmetric tJ model in the ferromagnetic regime and the
integrable spin-1 XXZ chain at \Delta=-1/\sqrt{2}. We argue that these models
include critical points described by the superconformal minimal models.Comment: 28 pages. v2: added new result on mapping to XXZ chai
Phase Diagram of the Extended Hubbard Model with Correlated Hopping Interaction
A one-dimensional model of interacting electrons with on-site ,
nearest-neighbor , and correlated-hopping interaction is studied
at half-filling using the continuum-limit field theory approach. The ground
state phase diagram is obtained for a wide range of coupling constants. In
addition to the insulating spin- and charge-density wave phases for large
and , respectively, we identify bond-located ordered phases corresponding to
an enhanced Peierls instability in the system for ,
and to a staggered magnetization located on bonds between
sites for , . The general ground state phase
diagram including insulating, metallic, and superconducting phases is
discussed.Comment: 8 pages, 4 eps-figure
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