Electron pitch-angle diffusion: resonant scattering by waves vs.nonadiabatic effects

International audienceIn this paper we investigate the electron pitchanglediffusion coefficients in the night-side inner magnetospherearound the geostationary orbit (L 7) due to magneticfield deformation. We compare the effects of resonantwave–particle scattering by lower band chorus waves and theadiabaticity violation of electron motion due to the strongcurvature of field lines in the vicinity of the equator. Fora realistic magnetic field configuration, the nonadiabatic effectsare more important than the wave–particle interactionsfor high energy (> 1 MeV) electrons. For smaller energy,the scattering by waves is more effective than nonadiabaticone. Moreover, the role of nonadiabatic effects increases withparticle energy. Therefore, to model electron scattering andtransport in the night-side inner magnetosphere, it is importantto take into account the peculiarities of high-energy electrondynamics

Fragmentation and Multifragmentation of 10.6A GeV Gold Nuclei

We present the results of a study performed on the interactions of 10.6A GeV gold nuclei in nuclear emulsions. In a minimum bias sample of 1311 interac- tions, 5260 helium nuclei and 2622 heavy fragments were observed as Au projec- tile fragments. The experimental data are analyzed with particular emphasis of target separation interactions in emulsions and study of criticalexponents. Multiplicity distributions of the fast-moving projectile fragments are inves- tigated. Charged fragment moments, conditional moments as well as two and three -body asymmetries of the fast moving projectile particles are determined in terms of the total charge remaining bound in the multiply charged projectile fragments. Some differences in the average yields of helium nuclei and heavier fragments are observed, which may be attributed to a target effect. However, two and three-body asymmetries and conditional moments indicate that the breakup mechanism of the projectile seems to be independent of target mass. We looked for evidence of critical point observable in finite nuclei by study the resulting charged fragments distributions. We have obtained the values for the critical exponents gamma, beta and tau and compare our results with those at lower energy experiment (1.0A GeV data). The values suggest that a phase transition like behavior, is observed.Comment: latex, revtex, 28 pages, 12 figures, 3tables, submitted to Europysics Journal