[en] The weak equivalence principle, a fundament of Einstein general relativity, states that gravitational mass and inertial mass are equal whatever the body. This equivalence principle has never been directly tested with antimatter. The GBAR (Gravitational Behaviour of Antimatter at Rest) experiment intends to test it by measuring the acceleration of ultra cold anti-hydrogens in free fall. The production of such anti-atoms requires a pulse of about 10¹⁰ positrons in a few tens of nanoseconds. This thesis focuses on the development of a new accumulation technique of positrons in a Penning-Malmberg trap in order to create this pulse. This new method is an improvement of the accumulation technique of Oshima et al.. This technique requires a non-neutral electron plasma to cool down positrons in the trap in order to confine them. A continuous beam delivers positrons and the trapping efficiency is about 0.4%. The new method needs a positron pulsed beam and the method efficiency is estimated at 80%. A part of this thesis was performed at Riken (Tokyo) on the trap of Oshima et al. to study the behavior of non-neutral plasmas in this type of trap and the first accumulation method. A theoretical model was developed to simulate the positron trapping efficiency. The description and the systematic study of the new accumulation technique with a pulsed positron beam are presented. They includes notably the optimization through simulation of the electromagnetic configuration of the trap and of the parameters of the used non-neutral plasmas. (author)

[en] The FORTE (Fast Onboard Recording of Transient Events) satellite was launched on 29 August 1997 and has been in continuous operation since that time. FORTE was placed in a nearly circular, 825-km-altitude, 70 degrees inclination orbit by a Pegasus rocket funded by Air Force Space Test Program. The Department of Energy funded the FORTE satellite, which was designed and built at Los Alamos. FORTE's successful launch and engineered robustness were a result of several years of dedicated work by the joint Los Alamos National Laboratory/Sandia National Laboratory project team, led through mission definition, payload and satellite development, and launch by Dr. Stephen Knox. The project is now led by Dr. Abram Jacobson. FORTE carries a suite of instruments, an optical system and a rf system, for the study of lightning and anthropogenic signals. As a result of this effort, new understandings of lightning events have emerged as well as a more complete understanding of the relationship between optical and rf lightning events. This paper will provide an overview of the FORTE satellite and will discuss the on orbit performance of the subsystems

[en] We have built a pulsed dye laser, pumped by the third harmonic of a pulsed Nd: YAG laser, the beam qualities of which (averaged resolution: 1.3 GHz (FWHM), obtained without the use of an intracavity etalon, low divergence < 1 mrad (FWHM), are essential. We have noted the possibility of a mono mode operating. We have used this laser to pump Tellurium molecule and we have observed that very numerous levels of the molecule give rise to laser transitions above 890 K quasi spontaneously for a pulse energy of about 40 μJ (pulse duration: 6 ns)

[en] Exotic nuclei currently not accessible will be delivered to the future DESIR facility for nuclear structure and astrophysics studies as well as for testing the Standard Model, using beta decay spectroscopy, laser spectroscopy and trap-based experiments. For most of the experiments, a high precision is needed and can be reached only if highly pure samples of exotic nuclei are delivered. Some particular physics cases will be presented. PIPERADE will be a system placed upstream the DESIR hall to purify the radioactive ion beam from undesired contaminants. It will consist of a radio-frequency quadrupole to bunch and cool the beam and of a double Penning-trap system to separate the isobaric species and accumulate the ions of interest. The purified beam will then be sent to the various experiments of the low-energy DESIR facility. The challenge for the present double Penning-trap system consists of being able to accumulate very large amounts of short-lived nuclei (10⁵-10⁶) while maintaining the resolving power necessary for isobar selection of at least 10⁵. For this purpose, studies of space charge effects and new excitation schemes are under investigation and are presented.

[en] We have installed in Saclay a facility for an intense positron source in November 2008. It is based on a compact 5.5 MeV electron linac and a reaction chamber with a tungsten target to produce positrons via pair production. The expected production rate for fast positrons is 4·10¹¹ per second. The study of moderation of fast positrons and the construction of a slow positron trap are underway. We have also developed an efficient positron-positronium convertor at CERN. These studies are parts of a project to demonstrate the feasibility of an experiment to produce the positively charged antihydrogen ion for a free fall measurement of neutral antihydrogen.

[en] We have installed in Saclay a facility for an intense positron source in November 2008. It is based on a compact 5.5 MeV electron linac connected to a reaction chamber with a tungsten target inside to produce positrons via pair production. The expected production rate for fast positrons is 5·10¹¹ per second. The study of moderation of fast positrons and the construction of a slow positron trap are underway. In parallel, we have investigated an efficient positron-positronium convertor using porous silica materials. These studies are parts of a project to produce positively charged antihydrogen ions aiming to demonstrate the feasibility of a free fall antigravity measurement of neutral antihydrogen.

[en] We are installing at CEA-Saclay a demonstration setup for an intense positron source. It is based on a compact 5.5 MeV electron linac used to produce positrons via pair production on a tungsten target. A relatively high current of 0.15 mA compensates for low positron efficiencies at low energy, which is below the neutron activation threshold. The expected production rate is 5·10¹¹ fast positrons per second. A set of coils is arranged to select the fast positrons from the diffracted electron beam in order to study the possibility of using a rare gas cryogenic moderator away from the main flux of particles. The commissioning of the linac is under way. This setup is part of a project to demonstrate the feasibility of an experiment to produce the H⁺ ions for a free fall measurement of neutral antihydrogen (H). Its small size and cost could be of interest for material science applications, after adaptation of the time structure.

[en] The ASACUSA collaboration aims at measuring the ground state hyperfine splitting of antihydrogen for probing fundamental symmetries. A cryogenic trap for mixing antiprotons and positrons serves as an antihydrogen source for in-flight spectroscopy. In order to be able to monitor the antihydrogen formation process, a dedicated Micromegas tracking detector has been designed and built to record the annihilation distribution in the trap. In this paper, we present the first results from antiproton annihilation data recorded with the Micromegas, together with a description of the event reconstruction algorithm.

[en] A Penning-trap isobar separator is currently under construction at CENBG (Bordeaux, France) and MPIK (Heidelberg, Germany) for a future installation at the SPIRAL2 /DESIR facility. This device aims at purifying the radioactive ion beams from undesired species, in order to deliver highly pure samples of exotic nuclei to the different set-ups which will be installed in the DESIR hall. The present manuscript describes the context and the motivations to build such a system, the targeted characteristics, and the studies to find an efficient purification method for large samples of isobaric species. (authors)

[en] The existence of a magnetic birefringence of vacuum is one of the most important predictions of quantum electrodynamics, which has not yet been verified. In this contribution, we present a new project, the BMV (Birefringence Magnetique du Vide) project, a collaboration between different Grenoble, Lyon and Toulouse institutes. The proposed experimental set-up, compared to previous attempts, should improve the signal level by about two orders of magnitude. Keystones of the proposed set-up are a very sensitive ellipsometer and a specially designed 1.5 m long 25 T pulsed magnet, which is under development in Toulouse, France