Experimental Observation of Proton Bunch Modulation in a Plasma at Varying Plasma Densities

We give direct experimental evidence for the observation of the full transverse self-modulation of a long, relativistic proton bunch propagating through a dense plasma. The bunch exits the plasma with a periodic density modulation resulting from radial wakefield effects. We show that the modulation is seeded by a relativistic ionization front created using an intense laser pulse copropagating with the proton bunch. The modulation extends over the length of the proton bunch following the seed point. By varying the plasma density over one order of magnitude, we show that the modulation frequency scales with the expected dependence on the plasma density, i.e., it is equal to the plasma frequency, as expected from theory

Experimental Observation of Plasma Wakefield Growth Driven by the Seeded Self-Modulation of a Proton Bunch

We measure the effects of transverse wakefields driven by a relativistic proton bunch in plasma with densities of 2.1 x 10(14) and 7.7 x 10(14) electrons/cm(3). We show that these wakefields periodically defocus the proton bunch itself, consistently with the development of the seeded self-modulation process. We show that the defocusing increases both along the bunch and along the plasma by using time resolved and time-integrated measurements of the proton bunch transverse distribution. We evaluate the transverse wakefield amplitudes and show that they exceed their seed value (< 15 MV/m) and reach over 300 MV/m. All these results confirm the development of the seeded self-modulation process, a necessary condition for external injection of low energy and acceleration of electrons to multi-GeV energy levels

[A severe side effect of antitubercular therapy: pyrazinamide induced thrombocytopenia].

International audienceThe haematological side effects of antitubercular drugs are not well known. We report the observation of a patient who received Rifater for the treatment of pulmonary tuberculosis. After one month of treatment, he developed an acute pulmonary infection, with neutropenia (1218/microl) and thrombocytopenia (109,000/microl), requiring suspension of his antitubercular drugs. After the reintroduction of he again developed thrombocytopenia (6,000/microl) associated with bleeding and required treatment with intravenous immunoglobulin. The introduction of a combination of moxifloxacin, isoniazid, pyrazinamide, and ethambutol was followed by a new relapse of the thrombocytopenia. Responsibility of pyrazinamide was then suspected and later confirmed by the evolution of platelet levels after stopping and reintroducing this antibiotic. This is the third reported case of pyrazinamide induced thrombocytopenia, whose frequency is probably underestimated because of the use of compound treatment

Sources and solutions for LHC transfer line stability issues

The LHC is filled through two 3 km long transfer lines from the last pre-injector, the SPS. During the LHC proton run 2011 large drifts, shot-by-shot and even bunch-bybunch trajectory variations were observed with the consequence of high losses at injection and frequent lengthy trajectory correction campaigns. The causes of these instabilities have been studied and will be presented in this paper. Based on the studies solutions have been proposed. The effect of the solutions will be shown and the remaining issues will be summarized

Tomography and imaging at the PSICHE beam line of the SOLEIL synchrotron

PSICHE (Pressure, Structure and Imaging by Contrast at High Energy) is the high-energy beam line of the SOLEIL synchrotron. The beam line is designed to study samples at extreme pressures, using diffraction, and to perform imaging and tomography for materials science and other diverse applications. This paper presents the tomograph and the use of the beam line for imaging, with emphasis on developments made with respect to existing instruments. Of particular note are the high load capacity rotation stage with free central aperture for installing large or complex samples and sample environments, x-ray mirror and filter optics for pink beam imaging, and multiple options for combining imaging and diffraction measurement. We describe how x-ray imaging techniques have been integrated into high-pressure experiments. The design and the specifications of the beam line are described, and several case studies drawn from the first user experiments are presented. Published by AIP Publishing

ELENA – An Updated Cost and Feasibility Study

To produce dense antiproton beams at very low energies (100 keV), it has been proposed to install a small decelerator ring between the existing AD ring and the experimental area. Phase-space blowup during deceleration is compensated by electron cooling such that the final emittances are comparable to the 5MeV beam presently delivered by the AD. An immediate consequence is a significant increase in the number of trapped antiprotons at the experiments as outlined in the proposal CERN/SPSC-2009-026; SPSC-P-338. This report describes the machine parameters and layout of the proposed ELENA (Extra Low ENergy Antiproton) ring and also gives an approximate estimate of cost and manpower needs. Since the initial estimate, published in 2007 (CERN-AB-2007-079), the ELENA design has evolved considerably. This is due to a new location in the AD hall to accommodate for the possibility of another experimental zone, as suggested by the SPSC, and also due to improvements in the ring optics and layout. The cost estimate that is presented is based on the initial document and has been updated according to the improvements in the design and layout. Where applicable, inflation has also been taken into account. The SPSC has recognized the substantial potential impact of ELENA on the AD experimental program and “strongly supports the ELENA proposal” (minutes of the meeting 29.09.2009) and the RB endorsed the conclusion from the SPSC concerning the strong scientific case for ELENA (minutes of the meeting 02.12.2009)

Extra Low ENergy Antiproton (ELENA) ring and its Transfer Lines: Design Report

This Report gives a full description of the ELENA Ring to be built within the circumference of the Antiproton Decelarator (AD) Ring, in Building 193 at CERN. The ELENA ring will further decelerate the antiprotons coming from the AD at the momentum of 100 MeV/c down to 13.7 MeV/c, which corresponds to the kinetic energy of 100 keV before extracting to the physics experiments in the same building. The history of such an extra low energy antiproton ring at CERN goes a long way back, and even to the Decelerator’s previous incarnation, the Low Energy Antiproton Ring (LEAR), which came into operation in 1983. Already at that time, there were physics’ requests to further decelerate the antiprotons expected from LEAR by proposals for ELENA. Appendix I illustrates the cover pages of two such CERN documents from 1982

AWAKE readiness for the study of the seeded self-modulation of a 400 GeV proton bunch

AWAKE is a proton-driven plasma wakefield acceleration experiment. We show that the experimental setup briefly described here is ready for systematic study of the seeded self-modulation of the 400 GeV proton bunch in the 10 m long rubidium plasma with density adjustable from 1 to 10 x 10(14) cm(-3). We show that the short laser pulse used for ionization of the rubidium vapor propagates all the way along the column, suggesting full ionization of the vapor. We show that ionization occurs along the proton bunch, at the laser time and that the plasma that follows affects the proton bunch