[en] We study theoretically and experimentally the population dynamics of the internal state of 60 MeV/u Kr³⁵⁺ ions traversing amorphous carbon foils. A quantum transport theory is developed that incorporates the state mixing induced by the wake field of the ion as well as all the coherences generated by the collisional and radiative redistribution of states. We show that the internal state of the ion is sensitive to collisional coherences and the wake field. The results of the full simulations are found to be in good agreement with experimental data

[en] We investigate the heating of the quasifree electrons in large rare-gas clusters (N exceeding 10⁵ atoms) by short laser pulses at moderate intensities (I≅10¹⁵ W cm^-2). We identify elastic large-angle backscattering of electrons at ionic cores in the presence of a laser field as an efficient heating mechanism. Its efficiency as well as the effect of collective electron motion, electron-impact ionization, and cluster charging are studied employing a mean-field classical transport simulation. Results for the absolute x-ray yields are in surprisingly good quantitative agreement with recent experimental results

[en] Although reliable models may predict the detection efficiency of semiconductor detectors, measurements are needed to check the parameters supplied by the manufacturers, namely, the thicknesses of dead layer, beryllium window, and crystal active area. The efficiency of three silicon detectors has been precisely investigated in their entire photon energy range of detection. In the zero to a few keV range, we developed a new method based on the detection of the 2E1 decay of the metastable Ar¹⁷⁺ 2s→1s transition. Very good theoretical knowledge of the energetic distribution of the 2E1 decay mode enables precise characterization of the absorbing layers in front of the detectors. In the high-energy range (>10 keV), the detector crystal thickness plays a major role in the detection efficiency and has been determined using a ²⁴¹Am source.

[en] A complete experimental study of the production and transport of long-lifetime excited states has been done for Ar¹⁸⁺ on solid C targets, at a velocity of 23 a.u., and for a range of thickness allowing us to vary the transport conditions from single collision to equilibrium (3.5 to 201 μg/cm²). A systematic determination of Ar¹⁷⁺ Rydberg l- and 2s-state populations has been performed using the x-ray spectroscopy technique. Results are compared with predictions of different transport simulations (developed on either a quantum or a classical phase space), which take into account multiple collisions and the strong polarization induced by the incoming ion (the wakefield). Using the continuum distorted-wave approximation for modeling the initial capture process, very good agreement is found between experimental Rydberg-state populations and theoretical approaches limited to the effect of multiple collisions. On the contrary, the transport of the metastable 2s state exhibits strong sensitivity to Stark mixing induced by the wakefield. The limitation of each theoretical approach is discussed with respect to the different experimental observables

[en] During experiments conducted on CEA-Saclay's Ultra Short Tuneable Laser, X-radiation has been studied both qualitatively (spectroscopy and average photon energy) and quantitatively (absolute rates and evolution laws), issued during the interaction of an effusive jet of rare gas aggregates (Ar, Kr, Xe comprising between 10⁴ and 10⁶ atom/aggregate) with a femtosecond power laser (illuminance up to a few 10¹⁷ W/cm²) The results presented in this paper are only dedicated to the Ar aggregates for which X-radiation was observed from strongly multicharged ions (up to Ar¹⁶⁺) having gaps in the K layers. The X-ray spectroscopy technique made it possible to determine for the first time absolute levels and the laws of evolution of the X emission as a function of all the parameters governing the interaction (intensity, polarization, wavelength and duration of the laser pulse as well as size, density and atomic number of aggregates). (author)

No abstract available

[en] The population dynamics of the internal state of 60 MeV/u Kr³⁵⁺ ions traversing amorphous carbon foils is studied theoretically and experimentally. This system is of particular interest as the times scales for collisional distribution, mixing due to the wake field, and radiative processes are comparable to each other. A transport theory based on a quantum-trajectory Monte Carlo method is developed, which treats the collisional and radiative redistribution of states on the same footing. The simulations exhibit clear signatures for the interplay between radiative decay and collisional mixing. Good agreement with experimental data is found

[en] We present a joint theoretical and experimental study of the time evolution of electronic states of highly charged hydrogenic ions formed by capture during transmission through solids as they undergo multiple collisions and radiative decay. For this transport problem we have developed an inhomogeneous nonunitary Lindblad master equation that allows for a description of open quantum systems with both sinks (electron loss) and source (capture) present. We apply this theoretical framework to study transient coherences created in electron capture by 13.6 MeV/amu Ar¹⁸⁺ ions transmitted through amorphous carbon foils and decoherence during subsequent interaction with the foil. In the limit of thin targets we can directly probe electron capture cross sections under single collision conditions, while for thicker targets we follow the partially coherent dynamics of the open quantum system in interaction with the solid as a function of interaction time. The calculated results are in close agreement with experimental data obtained at the LISE facility in GANIL. Photon intensities from excited argon ions were determined through high resolution x-ray spectroscopy in which individual fine structure components were resolved. Measurements were performed for a wide range of carbon foil thickness to study the time development of the excited state populations