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A simplified scheme for the provision of antiprotons at 100 MeV/c based on fast extraction is described. The scheme uses the existing p~ production target area and the modified Antiproton Collector Ring in their current location. The physics programme is largely based on capturing and storing antiprotons in Penning traps for the production and spectroscopy of antihydrogen. The machine modifications necessary to deliver batches of 1/spl times/10/sup 7/ p~/min at 100 MeV/c are described. Details of the machine layout and the experimental area in the existing AAC Hall are given.

The LEAR electron cooler uses dense electron beams. Because of this high density the large space-charge potential induces significant drawbacks for the cooling process itself. As a consequence a space-charge neutralisation system has been implemented on the cooler. It consists of two positively polarised pairs of electrodes, placed on the outside of the drift space, which aim to store the ionised positive ions of charge Z. The major difficulty arises in the neutralisation instabilities. This paper reports on the technological aspects, the measurement techniques and the results.

For the preparation of dense bunches of ions for the LHC it has been proposed to accumulate in a small storage ring the beam from a linac with an ECR source. The scheme involves combined transverse and longitudinal multiturn injection and strong electron cooling to free phase space for the next injection. Successful experiments to determine the optimum parameters of a low-energy ion accumulator were performed at the Low Energy Antiproton Ring (LEAR) with Pb-ions of charge state 52+ to 55+ at an energy of 4.2 MeV/u. The reported measurements include: lifetime for different charge states as a function of the electron cooler current, cooling rates with different optical settings, efficiencies of the combined multiturn injection and results of accumulation. The transformation of LEAR into an accumulator ring for a wide range of ion species will be based on these results.

The LEAR machine is foreseen to be used as a lead ion accumulator in the injector chain for the LHC. Therefore, to test the principle of Pb54+ ion accumulation in LEAR, at 4.2 MeV/u, a number of studies and experiments have been made aimed at determining the improvements and modifications necessary to fulfill the LHC requirements. Amongst subjects studied we have investigated: a) The ion production and the injection line matching, b) The linac energy ramping in view of accumulation through combined longitudinal-transverse multi-turn injection, c) The ion beam lifetime and recombination processes, and finally d) The electron cooling time, as a function of the lattice parameters at the cooler. Recent experiments and measurements will be reported and commented in this paper. Also mentioned are some particular diagnostic methods.

Multi wire proportional chambers (MWPC's) are used in many transfer lines and experimental areas at CERN. These chambers are mostly used for beam steering but can also provide reliable profiles measurements. MWPC's, however, also present intrinsic limitations such as limited spatial resolution and gain drop at high rate. Experience shows that MWPCs are fragile and expensive both to produce and repair. Profile measurements from MWPC's can not always be trusted. This is the case with the chambers installed in CERN's low energy antiproton decelerator (AD) which are not only destructive for the beam, but also strongly perturb the profile measurement due to the low energy of the AD beam. For these reasons, we have developed a new, robust, low cost and high precision profile monitor based on gas electron multiplication (GEM). Our GEM detector is designed to be backward compatible as a direct replacement for our old MWPCs. The GEM detector performs simultaneous profile measurements in the both X and Y plane. This paper presents the two first prototypes of the GEM profile monitor and report on measurements from both low energy and high energy beams. Finally highlights and drawbacks of both detectors are discussed with a view to replace MWPC's with GEM's for many applications at CERN.