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 35^{35}Cl+24^{24}Mg System at E/A ≈\approx 8 MeV/Nucleon

Compound-nucleus fusion and binary-reaction mechanisms have been investigated for the $^{35}$Cl+$^{24}$Mg system at an incident beam energy of E$_{Lab}$= 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

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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

Simulations of impurity transport with TERESA and GYSELA codes

International audienceWe analyze properties of the radial turbulent transport of light to heavy impurities based on global gyrokinetic simulations. We describe how transport depends on impurity concentration, charge, mass, gradients, poloidal asymmetry, rotation, and on the nature of the underlying dominant instability – either Ion Temperature Gradient (ITG) or Trapped Electron Mode (TEM). We used the GYSELA-X code for ITG simulations with a realistic collision operator [1] and improved boundary conditions, and TERESA code for collisionless TEM simulations with impurities [2]. GYSELA-X describes the 5D distribution of gyrocenters, while TERESA describes the 4D distribution of gyro-bounce-centers (banana centers).TERESA simulations indicate that the validity of the usual passive treatment of impurities is limited to a concentration C of W40+ tungsten below 2x10-4. We describe the impact of C on linear growth rate, turbulence intensity, and impurity density flux. A transition centered around C Z^2 = 1.1 is significantly steeper for the flux. This is due to a mechanism of phase-synchronization between impurity density and potential fluctuations, which quenches impurity transport [3].Treating trace impurities self-consistently, we observe how diffusive impurity transport increases (resp. decreases) with charge number Z for TEM (TIM) turbulence. Mass number is less impacting [4]. The direction of thermo-diffusion depends on the nature of turbulence as expected from quasilinear theory, and on the impurity temperature profile. Curvature pinch is inward except in some negative magnetic shear cases.GYSELA-X simulations confirm that turbulent (resp. neoclassical) transport dominates for light (heavy) impurity leading to hollow (peaked) density profile. Pfirsch-Schlüter flux dominates for tungsten. Behavior of intermediate-mass impurity (argon) is more subtle, but banana-plateau flux dominates in the core. Turbulence generates 20% up-down asymmetry for high-Z impurities, impacting neoclassical transport [5]. Toroidal rotation increases in-out asymmetry and central tungsten accumulation.[1] D. Estève, et al., Nucl. Fusion 58 (2018) 036013[2] M. Idouakass et al., Phys. Plasmas 25 (2018) 062307[3] M. Lesur et al., Nucl. Fusion 60 (2020) 036016[4] E. Gravier et al., Phys. Plasmas 26 (2019) 082306[5] K. Lim et al., Nucl. Fusion 61 (2021) 046037[6] C. Angioni et al., Nucl. Fusion 52 (2012) 11400