DSM (France)

We present continuum random phase approximation calculations (CRPA) for neutrino-induced quasielastic scattering off atomic nuclei. The validity of our formalism is checked by a careful confrontation of its results with semi-inclusive double-differential electron scattering data. We pay special attention to excitations in the giant resonance region. The CRPA is well-suited for the description of interactions in this energy range. We aim at providing a uniform description of one-nucleon knockout processes over the whole energy range from threshold to the quasielastic peak. Our calculations point to the fact that low-energy and giant-resonance excitations provide a non-negligible contribution to the interaction strength, especially at forward lepton-scattering angles.

The CaLIPSO project aims to develop a high precision brain-scanning PET device with time-of-flight capability. The proposed device uses an innovative liquid, the TriMethyl Bismuth, as the detection medium. It detects simultaneously the ionization and optical signals from the 511 keV gamma conversion. In this paper we present the design, the Monte Carlo simulation, and the tests results for the CaLIPSO optical prototype. In this prototype we demonstrated the ability to detect efficiently the low number of the optical photons produced by the relativistic electron from the gamma conversion through the Cherenkov effect. The time resolution of the current prototype is limited by the moderate time transition spread of the PMT, but should be improved to the level better than 100 ps (FWHM) by using micro-channel-plate PMT according to the Geant 4 simulation.

With the term microinstabilities, we indicate a class of plasma drift waves such as the ion temperature gradient (ITG) mode, the trapped electron mode (TEM), and the electromagnetic Alfvénic ion temperature gradient (AITG) mode. They are usually driven by spatial gradients in the plasma and they are held responsible for anomalous transport and enhanced heat flux in tokamaks. Their understanding is therefore crucial for the development of magnetically confined plasma fusion devices. Our approach is based on the gyrokinetic model (Hahm 1988) for particle dynamics. The gyrokinetic nonlinear Vlasov equation, in the presence of an electromagnetic perturbation (Brizard 1989, 1995), is derived using Lie perturbation theory (Cary and Littlejohn 1983) to average out the fast particle motion around the gyrocenter. We have linearized the gyrokinetic Vlasov equation and added the quasi‐neutrality equation and Ampère's law, providing closure to the system. A temporal spectral formulation is used, ensuring the absence of numerical instabilities due to high frequency modes. The equations are simplified with a large aspect ratio approximation for an axisymmetric toroidal configuration. The fields are expanded in a Fourier series in the three spatial directions (radial, poloidal, and toroidal) reducing the problem in a matrix form. The code EM‐GLOGYSTO (Brunner et al. 1998; Falchetto et al. 2003; Joint Varenna‐Lausanne International Workshop 2002) has been developed to look at its solutions. Recently, we have included in the model an electrostatic equilibrium potential in order to provide E×B sheared flow. The code has been optimized for running in a parallel environment using MPI routines, and it allows us to study frequencies, growth rates, and mode structures of electromagnetic microinstabilities. Results on an AITG mode are shown to illustrate these features.

This paper reports a study of the high-temperature stability of ion-implanted yttria-stabilized zirconia and magnesium aluminate spinel, which are foreseen as matrices for the transmutation of nuclear waste. Stable analogs of radiotoxic fission products (Cs) were implanted into both materials and the stability of the implanted systems was studied upon annealing at a high temperature. Rutherford backscattering spectrometry experiments with a macro- and a micro-ion-beam, scanning electron microscopy, and atomic force microscopy observations show that the annealing behavior strongly depends on the material. In zirconia Cs begins to desorb out of the crystal at 550°C in samples which remain homogeneous. On the contrary, the desorption of Cs is observed at 850°C in spinel by the exfoliation of the surface of the samples.

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