21 research outputs found
Heavy Residue Formation in 20 MeV/nucleon 197Au + 90Zr collisions
The yields and velocity distributions of heavy residues and fission fragments
from the reaction of 20 MeV/nucleon 197Au + 90Zr have been measured using the
MSU A1200 fragment separator. A bimodal distribution of residues is observed,
with one group, resulting from peripheral collisions, having fragment mass
numbers A=160-200, while the other group, resulting from ``hard'' collisions,
has A=120-160. This latter group of residues can be distinguished from fission
fragments by their lower velocities. A model combining deep-inelastic transfer
and incomplete fusion for the primary interaction stage and a statistical
evaporation code for the deexcitation stage has been used to describe the
properties of the product distributions.Comment: 19 pages, 6 figures, preprint submitted to Nucl. Phys.
Fusion and Binary-Decay Mechanisms in the Cl+Mg System at E/A 8 MeV/Nucleon
Compound-nucleus fusion and binary-reaction mechanisms have been investigated
for the Cl+Mg system at an incident beam energy of E= 282
MeV. Charge distributions, inclusive energy spectra, and angular distributions
have been obtained for the evaporation residues and the binary fragments.
Angle-integrated cross sections have been determined for evaporation residues
from both the complete and incomplete fusion mechanisms. Energy spectra for
binary fragment channels near to the entrance-channel mass partition are
characterized by an inelastic contribution that is in addition to a fully
energy damped component. The fully damped component which is observed in all
the binary mass channels can be associated with decay times that are comparable
to, or longer than the rotation period. The observed mass-dependent cross
sections for the fully damped component are well reproduced by the fission
transition-state model, suggesting a fusion followed by fission origin. The
present data cannot, however, rule out the possibility that a long-lived
orbiting mechanism accounts for part or all of this yield.Comment: 41 pages standard REVTeX file, 14 Figures available upon request -
OSS (Outer Solar System): A fundamental and planetary physics mission to Neptune, Triton and the Kuiper Belt
The present OSS mission continues a long and bright tradition by associating
the communities of fundamental physics and planetary sciences in a single
mission with ambitious goals in both domains. OSS is an M-class mission to
explore the Neptune system almost half a century after flyby of the Voyager 2
spacecraft. Several discoveries were made by Voyager 2, including the Great
Dark Spot (which has now disappeared) and Triton's geysers. Voyager 2 revealed
the dynamics of Neptune's atmosphere and found four rings and evidence of ring
arcs above Neptune. Benefiting from a greatly improved instrumentation, it will
result in a striking advance in the study of the farthest planet of the Solar
System. Furthermore, OSS will provide a unique opportunity to visit a selected
Kuiper Belt object subsequent to the passage of the Neptunian system. It will
consolidate the hypothesis of the origin of Triton as a KBO captured by
Neptune, and improve our knowledge on the formation of the Solar system. The
probe will embark instruments allowing precise tracking of the probe during
cruise. It allows to perform the best controlled experiment for testing, in
deep space, the General Relativity, on which is based all the models of Solar
system formation. OSS is proposed as an international cooperation between ESA
and NASA, giving the capability for ESA to launch an M-class mission towards
the farthest planet of the Solar system, and to a Kuiper Belt object. The
proposed mission profile would allow to deliver a 500 kg class spacecraft. The
design of the probe is mainly constrained by the deep space gravity test in
order to minimise the perturbation of the accelerometer measurement.Comment: 43 pages, 10 figures, Accepted to Experimental Astronomy, Special
Issue Cosmic Vision. Revision according to reviewers comment
Novel integrated polarization analyzer sensor made by ion-exchange in glass
International audienc
Novel integrated polarization analyzer sensor made by ion-exchange in glass
International audienceIn this paper, we propose a novel integrated polarization analyzer sensor (IPAS) made by ion exchange on a glass substrate. It is capable to determine the polarization state of a light beam: elliptical, circular or linear. Furthermore, in the first case, the sensor measures the ellipse's eccentricity and the angle between its major axis and the x-axis of the IPAS (parallel to the glass' top surface). Also, for linear polarization, the angle between polarization direction and the x-axis of the IPAS is measured. The IPAS consists in two Y-junctions that gives three different outputs. The first one is directly one of the two output waveguides of the first Y-junction. The two other outputs are the waveguides following the second Y-junction. Before the latter, a piezoelectric plate creates an artificial anisotropy when it is excited electrically. For each one of the three output signals, a polarizer is inserted between the waveguide's end and a photo-detector. It is demonstrated here that, with adequate signal processing, it is possible to obtain all the information on the polarization state of a light beam
Applications of the Acousto-Optic Effect on Glass Integrated Optic Devices
International audienc
Applications of the Acousto-Optic Effect on Glass Integrated Optic Devices
International audienceWe present in this paper a study of acousto-optic interactions with guided waves on glass substrate. A beam of elastic of waves in the Megahertz range, generated with a PZT ceramic, crosses a waveguide realised by ion-exchange in a glass substrate. Elastic waves modify locally the refractive index of glass. We make use of this effect to propose novel integrated sensors like a polarization analyzer sensor and to improve devices like optical modulators and displacement sensor
Towards an optical measurement of the Boltzmann constant at the 10
We present a new method for direct determination of the
Boltzmann constant by laser spectroscopy. The principle consists in
recording the linear absorption in a vapour of an atomic or molecular line
at a controlled temperature around 273.15 K. By eliminating the pressure
broadening, we deduced the pure Doppler width which gives a first optical
measurement of the Boltzmann constant kB. The present determination
should be significantly improved in the near future and contribute to a new
definition of kelvin