1,422 research outputs found
Interpretation of Coulomb breakup of 31Ne in terms of deformation
The recent experimental data on Coulomb breakup of the nucleus Ne are
interpreted in terms of deformation. The measured large one-neutron removal
cross-section indicates that the ground state of Ne is either s- or
p-halo. The data can be most easily interpreted as the spin of the ground state
being 3/2 coming from either the Nilsson level [330 1/2] or [321 3/2]
depending on the neutron separation energy . However, the possibility of
1/2 coming from [200 1/2] is not excluded. It is suggested that if the
large ambiguity in the measured value of of Ne, 0.29 MeV,
can be reduced by an order of magnitude, say to be 100 keV, one may get a
clear picture of the spin-parity of the halo ground state.Comment: 8 pages, 4 figure
Dominance of Nuclear Processes in the Dissociation of 8B
We study the break-up of 8B in collisions with heavy-ions. The process is
described in terms of inelastic excitations leading to states in the continuum.
The effects of the nuclear and coulomb fields are included on the same
footing in the microscopic construction of the transition matrix elements. The
interplay between coulomb and nuclear excitation processes differs
significantly from the situation encountered in reactions involving systems
close to the stability line. In particular, nuclear excitation is found to
remain predominant at energies well below the coulomb barrier,Comment: TEX file + 11 postscript figure
The Yrast Spectra of Weakly Interacting Bose-Einstein Condensates
The low energy quantal spectrum is considered as a function of the total
angular momentum for a system of weakly interacting bosonic atoms held together
by an external isotropic harmonic potential. It is found that besides the usual
condensation into the lowest state of the oscillator, the system exhibits two
additional kinds of condensate and associated thermodynamic phase transitions.
These new phenomena are derived from the degrees of freedom of "partition
space" which describes the multitude of different ways in which the angular
momentum can be distributed among the atoms while remaining all the time in the
lowest state of the oscillator
Phytohaemagglutinin on maternal and umbilical leukocytes
Almost all the umbilical lymphocytes showed more extensive blast cell formation
than that of their mother's lymphocytes with PHA. Pathological conditions of mother in pregnancy and labor such as anemia, gestational toxicosis,
difficult labor and asphyxia of babies, inhibited the normal response of both maternal and umbilical lymphocytes to PHA.</p
Change of shell structure and magnetic moments of odd-N deformed nuclei towards neutron drip line
Examples of the change of neutron shell-structure in both weakly-bound and
resonant neutron one-particle levels in nuclei towards the neutron drip line
are exhibited. It is shown that the shell-structure change due to the weak
binding may lead to the deformation of those nuclei with the neutron numbers 8, 20, 28 and 40, which are known to be magic numbers in stable
nuclei. Nuclei in the "island of inversion" are most easily and in a simple
manner understood in terms of deformation. As an example of spectroscopic
properties other than single-particle energies, magnetic moments of some
weakly-bound possibly deformed odd-N nuclei with neutron numbers close to those
traditional magic numbers are given, which are calculated using the wave
function of the last odd particle in deformed Woods-Saxon potentials.Comment: 21 pages, 6 figure
Rotations of nuclei with reflection asymmetry correlations
We propose a collective Hamiltonian which incorporates interactions capable
to generate rotations in nuclei with simultaneous presence of octupole and
quadrupole deformations. It is demonstrated that the model formalism could be
applied to reproduce the staggering effects observed in nuclear octupole bands.
On this basis we propose that the interactions involved would provide a
relevant handle in the study of collective phenomena in nuclei and other
quantum mechanical systems with reflection asymmetry correlations.Comment: LaTeX, 9 pages plus 3 figures given in separate .ps files. To appear
in the proceedings of the International Conference on Nuclear Structure and
Related Topics (Dubna, Russia, 6-10/6/2000), ed. R. Jolos, V. Voronov, et a
Nilsson diagrams for light neutron-rich nuclei with weakly-bound neutrons
Using Woods-Saxon potentials and the eigenphase formalism for one-particle
resonances, one-particle bound and resonant levels for neutrons as a function
of quadrupole deformation are presented, which are supposed to be useful for
the interpretation of spectroscopic properties of some light neutron-rich
nuclei with weakly-bound neutrons. Compared with Nilsson diagrams in text books
which are constructed using modified oscillator potentials, we point out a
systematic change of the shell structure in connection with both weakly-bound
and resonant one-particle levels related to small orbital angular momenta
. Then, it is seen that weakly-bound neutrons in nuclei such as
C and Mg may prefer to being deformed as a result of
Jahn-Teller effect, due to the near degeneracy of the 1d-2s
levels and the 1f-2p levels in the spherical potential,
respectively. Furthermore, the absence of some one-particle resonant levels
compared with the Nilsson diagrams in text books is illustrated.Comment: 12 pages, 5 figure
Superconformal Symmetry, The Supercurrent And Non-BPS Brane Dynamics
The Noether currents associated with the non-linearly realized
super-Poincare' symmetries of the Green-Schwarz (Nambu-Goto-Akulov-Volkov)
action for a non-BPS p=2 brane embedded in a N=1, D=4 target superspace are
constructed. The R symmetry current, the supersymmetry currents, the
energy-momentum tensor and the scalar central charge current are shown to be
components of a world volume supercurrent. The centrally extended
superconformal transformations are realized on the Nambu-Goldstone boson and
fermion fields of the non-BPS brane. The superconformal currents form
supersymmetry multiplets with the world volume conformal central charge current
and special conformal current being the primary components of the supersymmetry
multiplets containing all the currents. Correspondingly the superconformal
symmetry breaking terms form supersymmetry multiplets the components of which
are obtainable as supersymmetry transformations of the primary currents'
symmetry breaking terms.Comment: 27 pages, LaTeX, Summary Tables Adde
Cranked Hartree-Fock-Bogoliubov Calculation for Rotating Bose-Einstein Condensates
A rotating bosonic many-body system in a harmonic trap is studied with the
3D-Cranked Hartree-Fock-Bogoliubov method at zero temperature, which has been
applied to nuclear many-body systems at high spin. This method is a variational
method extended from the Hartree-Fock theory, which can treat the pairing
correlations in a self-consistent manner. An advantage of this method is that a
finite-range interaction between constituent particles can be used in the
calculation, unlike the original Gross-Pitaevskii approach. To demonstrate the
validity of our method, we present a calculation for a toy model, that is, a
rotating system of ten bosonic particles interacting through the repulsive
quadrupole-quadrupole interaction in a harmonic trap. It is found that the
yrast states, the lowest-energy states for the given total angular momentum,
does not correspond to the Bose-Einstein condensate, except a few special
cases. One of such cases is a vortex state, which appears when the total
angular momentum is twice the particle number (i.e., ).Comment: accepted to Phys. Rev.
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