Microwave Instability and Impedance Measurements in the CERN SPS

The single bunch intensity of protons in the SPS is limited by the microwave instability. The main sources of the SPS impedance responsible for this instability have been determined by measurements of the spectrum of unstable single bunches injected into the machine. New experimental data and the improved impedance model have helped to explain some previously contradictory results concerning the microwave instability threshold - one of the critical parameters for the SPS as LHC injector. Ways of curing the instability are discussed

Material Damage Test with 450GeV LHC-type beam

The design of LHC protection elements is based on assumptions on damage levels, which are derived from simulations. A dedicated experiment was prepared and carried out to cross-check the validity of this approach by trying to damage material in a controlled way with beam. The impact of a 450 GeV beam extracted from the SPS on a specially designed high-Z target with a simple geometry, comprising several typical materials used for LHC equipment, was simulated. The beam intensities for the test were chosen to exceed the damage limits of parts of the target. Results of the simulations are presented and compared with test results

Effets combinés de l'enherbement et du porte-greffe sur le comportement agronomique du Cabernet Franc

International audienc

Effets combinés de l'enherbement et du porte-greffe sur le comportement agronomique du Chenin

International audienc

Extending the chemical space of CAZymes: how and why?

International audienc

X-ray spectroscopy characterization of Ar17+ produced by an ECRIS in the afterglow mode

International audienceAn electron–cyclotron–resonance ion source (ECRIS) operating in the afterglow mode allows to produce pulsed highly charged ion beams. We present a characterization of the first production of pulsed Ar17+ ions from an ECRIS using X-ray spectroscopy techniques. An ion current increase of a factor 3-4 compared to the continuous operating mode with a short rise time (< 100 µs) and a full width at half maximum of 500 µs has been obtained

Sub-picosecond dynamic of intense laser-clusters interaction : keV X-ray and highly charged ions production

International audienceWe have performed studies of keV X-ray production from (Ar)n , (Kr)n and (Xe)n rare gas clusters (with n between 104 and 106 atoms/cluster) submitted to intense (~10^18 W/cm2) infrared (800 nm) laser pulses. Up to 10^6 3 keV photons per pulse at a moderate (~10^15/cm3) atomic density have been observed. High resolution spectroscopy studies in the case of (Ar)n clusters have also been performed, giving unambiguous evidence of highly charged (up to heliumlike) ions with K vacancies production. We have determined the photon energies and the absolute photon emission yields as a function of several physical parameters governing the interaction : size and atomic number of the clusters, peak intensity of the laser. Unexpectedly low laser intensity thresholds (~10^15Wcm-2) have been measured. The results obtained indicate nevertheless that X-rays may be emitted before cluster explosion on a subpicosecond time scale, and that several mechanisms must be involved in the first stage of the production of the hot nanoplasma induced from each cluster

Interaction of slow HCI with gaseous targets: absolute x-ray emission cross sections and contribution of multi-capture processes

Expérience GANIL/ARIBEInternational audienceSynopsis Collisions of 15 keV/q Ar17+ ions with a gaseous jet have been studied by high-resolution x-ray spectroscopy techniques. Absolute x-ray emission cross sections and initial population mechanisms on singly and multiple excited states are extracted

Electronic sputtering of LiF by Krypton (10 MeV/u): size dependent energy distributions of Li+(LiF)n clusters

International audienc