8,389 research outputs found
A Method to Calculate Fission-Fragment Yields versus Proton and Neutron Number in the Brownian Shape-Motion Model. Application to calculations of U and Pu charge yields
We propose a method to calculate the two-dimensional (2D) fission-fragment
yield versus both proton and neutron number, with inclusion of
odd-even staggering effects in both variables. The approach is to use Brownian
shape-motion on a macroscopic-microscopic potential-energy surface which, for a
particular compound system is calculated versus four shape variables:
elongation (quadrupole moment ), neck , left nascent fragment
spheroidal deformation , right nascent fragment deformation
and two asymmetry variables, namely proton and neutron
numbers in each of the two fragments. The extension of previous models 1)
introduces a method to calculate this generalized potential-energy function and
2) allows the correlated transfer of nucleon pairs in one step, in addition to
sequential transfer. In the previous version the potential energy was
calculated as a function of and of the compound system and its shape,
including the asymmetry of the shape. We outline here how to generalize the
model from the "compound-system" model to a model where the emerging fragment
proton and neutron numbers also enter, over and above the compound system
composition
Effect of stripe order strength for the Nernst effect in La_{2-x}Sr_xCu_4 single crystals
We have precisely measured the Nernst effect in Nd-doped
LaSrCuO single crystals with controlling the strength
(stability) of the stripe order. We found that the onset temperature
, where the Nernst signal starts increasing, does not change
conspicuously in spite of Nd-doping. At low temperatures, on the other hand,
the absolute value of the Nernst signal is strongly suppressed in accordance
with the strength of the stripe order. These results imply that the fluctuation
of (charge) stripe order enhances the Nernst signal below at high
temperatures, and then the stripe order enhanced by Nd-doping suppresses the
superconducting fluctuation to reduce the Nernst signal at low temperatures. We
also observed an increase of the Nernst signal below the charge order
temperature which is observed in diffraction measurement.Comment: 3pages, 2figure
Nuclear ground-state masses and deformations: FRDM(2012)
We tabulate the atomic mass excesses and binding energies, ground-state
shell-plus-pairing corrections, ground-state microscopic corrections, and
nuclear ground-state deformations of 9318 nuclei ranging from O to
. The calculations are based on the finite-range droplet macroscopic
model and the folded-Yukawa single-particle microscopic model. Relative to our
FRDM(1992) mass table in {\sc Atomic Data and Nuclear Data Tables} [{\bf 59}
185 (1995)], the results are obtained in the same model, but with considerably
improved treatment of deformation and fewer of the approximations that were
necessary earlier, due to limitations in computer power. The more accurate
execution of the model and the more extensive and more accurate experimental
mass data base now available allows us to determine one additional
macroscopic-model parameter, the density-symmetry coefficient , which was
not varied in the previous calculation, but set to zero. Because we now realize
that the FRDM is inaccurate for some highly deformed shapes occurring in
fission, because some effects are derived in terms of perturbations around a
sphere, we only adjust its macroscopic parameters to ground-state masses. The
values of ten constants are determined directly from an optimization to fit
ground-state masses of 2149 nuclei ranging from O to Sg
and Hs. The error of the mass model is 0.5595~MeV. We also
provide masses in the FRLDM, which in the more accurate treatments now has an
error of 0.6618 MeV. But in contrast to the FRDM, it is suitable for studies of
fission and has been extensively so applied elsewhere, with FRLDM(2002)
constants. The FRLDM(2012) fits 31 fission barrier heights from Se to
Cf with a root-mean-square deviation of 1.052 MeV.Comment: 233 pages, 41 figures. arXiv admin note: text overlap with
arXiv:nucl-th/930802
Pure Collective Precession Motion of High-Spin Torus Isomer
We investigate the precession motion of the exotic torus configuration in
high-spin excited states of Ca. For this aim, we use the
three-dimensional time-dependent Hartree-Fock (TDHF) method. Although the
high-spin torus isomer is a unique quantum object characterized by the
alignment of angular momenta of independent single-particle motions, we find
that the obtained moment of inertia for rotations about an axis perpendicular
to the symmetry axis is close to the rigid-body value. We also analyze the
microscopic structure of the precession motion using the random-phase
approximation (RPA) method for high-spin states. In the RPA calculation, the
precession motion of the torus isomer is generated by coherent superposition of
many one-particle-one-hole excitations across the sloping Fermi surface that
strongly violates the time-reversal symmetry. By comparing results of the TDHF
and the RPA calculations, we find that the precession motion obtained by the
TDHF calculation is a pure collective motion well decoupled from other
collective modes
Real-time simulation of jet engines with digital computer. 1: Fabrication and characteristics of the simulator
The fabrication and performance of a real time jet engine simulator using a digital computer are discussed. The use of the simulator in developing the components and control system of a jet engine is described. Comparison of data from jet engine simulation tests with actual engine tests was conducted with good agreement
Three triton states in 9Li
We focus on a characteristic non-alpha cluster structure in light
neutron-rich nuclei; three triton structure in 9Li. This is an analogy to the
case of three alpha state in 12C (Hoyle state). The alpha clusters behave as
bosons. however tritons have Fermionic nature, and how the three cluster
structure is different from 12C is an intriguing problem. For this purpose, we
introduce three triton wave functions. In addition, alpha+t+n+n wave functions
are prepared to describe other low-lying states of 9Li, and the coupling effect
between them is taken into account. The states with dominantly the three triton
components appear below the three triton threshold energy, where three triton
correlation is important, however the root mean square radius is not enhanced
contrary to the alpha gas states in 12C and 16O.Comment: 5 pages, 4 figure
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