92,963 research outputs found
Asymmetry and the Neutron Skin in Heavy Nuclei
In heavy nuclei the spatial distribution of protons and neutrons is
different. At CERN SPS energies production of and differs for
, , and scattering. These two facts lead to an impact
parameter dependence of the to ratio in
collisions. A recent experiment at CERN seems to confirm qualitatively these
predictions. It may open a possibility for determination of neutron density
distribution in nuclei.Comment: 6 pages and 2 figures, a talk by A.Szczurek at the international
conference MESON2004, June 4-8, Cracow, Polan
Quality control of microelectronic wire bonds
Report evaluates ultrasonic bonding of small-diameter aluminum wire joined to ceramic substrates metalized with thin-film and thick-film gold. Quick testing technique for nondestructive location of poor wire bonds is also presented
Antenna simulator permits preinstallation system checkout
Antenna simulator provides for evaluation checkout of corporate feeds, monopulse sum-and-difference networks, etc., in a shielded environment prior to system checkout on an antenna pattern range. This technique is useful wherever simulation of monopulse antenna element characteristics is desired for checkout of ancillary equipment in a controlled environment
Monopulse system with an electronic scanner
Electronic and mechanical scanning control system for monopulse tracking antenn
A model for orientation effects in electron‐transfer reactions
A method for solving the single‐particle Schrödinger equation with an oblate spheroidal potential of finite depth is presented. The wave functions are then used to calculate the matrix element T_BA which appears in theories of nonadiabatic electron transfer. The results illustrate the effects of mutual orientation and separation of the two centers on TBA. Trends in these results are discussed in terms of geometrical and nodal structure effects. Analytical expressions related to T_BA for states of spherical wells are presented and used to analyze the nodal structure effects for T_BA for the spheroidal wells
Fundamental-measure density functional for the fluid of aligned hard hexagons: New insights in fundamental measure theory
In this article we obtain a fundamental measure functional for the model of
aligned hard hexagons in the plane. Our aim is not just to provide a functional
for a new, admittedly academic, model, but to investigate the structure of
fundamental measure theory. A model of aligned hard hexagons has similarities
with the hard disk model. Both share "lost cases", i.e. admit configurations of
three particles in which there is pairwise overlap but not triple overlap.
These configurations are known to be problematic for fundamental measure
functionals, which are not able to capture their contribution correctly. This
failure lies in the inability of these functionals to yield a correct low
density limit of the third order direct correlation function. Here we derive
the functional by projecting aligned hard cubes on the plane x+y+z=0. The
correct dimensional crossover behavior of these functionals permits us to
follow this strategy. The functional of aligned hard cubes, however, does not
have lost cases, so neither had the resulting functional for aligned hard
hexagons. The latter exhibits, in fact, a peculiar structure as compared to the
one for hard disks. It depends on a uniparametric family of weighted densities
through a new term not appearing in the functional for hard disks. Apart from
studying the freezing of this system, we discuss the implications of the
functional structure for new developments of fundamental measure theory.Comment: 10 pages, 9 figures, uses RevTeX
Soft core fluid in a quenched matrix of soft core particles: A mobile mixture in a model gel
We present a density-functional study of a binary phase-separating mixture of
soft core particles immersed in a random matrix of quenched soft core particles
of larger size. This is a model for a binary polymer mixture immersed in a
crosslinked rigid polymer network. Using the replica `trick' for
quenched-annealed mixtures we derive an explicit density functional theory that
treats the quenched species on the level of its one-body density distribution.
The relation to a set of effective external potentials acting on the annealed
components is discussed. We relate matrix-induced condensation in bulk to the
behaviour of the mixture around a single large particle. The interfacial
properties of the binary mixture at a surface of the quenched matrix display a
rich interplay between capillary condensation inside the bulk matrix and
wetting phenomena at the matrix surface.Comment: 20 pages, 5 figures. Accepted for Phys. Rev.
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