S. Maury

Measurement of the lifetime of Pb52+, Pb53+ and Pb54+ beams at 4.2 MeV per nucleon subject to electron cooling

Abstract By measuring the lifetime of stored beams, the recombination of the ions with cooling electrons was investigated. Rates found are larger than expected for radiative electron capture and significantly higher for Pb53+ than for Pb54+ and Pb52+. These results are important for the design of the lead ion injection system for the Large Hadron Collider and for recombination theories.

The antiproton decelerator: AD

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 CERN antiproton decelerator (AD) in 2002: status, progress and machine development results

After 3 years of operation, the antiproton decelerator performance is close to the design specifications. A review of the improvements over the years is given, along with results of machine development sessions that have taken place at regular intervals. An outlook for 2003 with details of planned and possible changes is also presented.

Commissioning and first operation of the Antiproton Decelerator (AD)

The Antiproton Decelerator (AD) is a simplified source of antiprotons which provides low energy antiprotons for experiments, replacing four machines: AC (Antiproton Collector), AA (Antiproton Accumulator); PS and LEAR (Low Energy Antiproton Ring), shutdown in 1996. The former AC was modified to include deceleration and electron cooling. The AD started operation in July 2000 and has since delivered cooled beam at 100 MeV/c (kinetic energy of 5.3 MeV) to 3 experiments (ASACUSA, ATHENA and ATRAP) for 1500 h. The flux (up to 2.5 /spl times/ 10 pbar /s delivered in short pulses of 330 ns every 110 s) and the quality of the ejected beam are not far from the design specifications. A linear RF quadrupole decelerator (RFQD) was commissioned in November 2000 to post-decelerate the beam for ASACUSA from 5.3 MeV to about 15 keV. Problems encountered in converting the fixed energy AC into a decelerating machine will be outlined, and the present status of the AD, including the performance of the cooling systems and the special diagnostics to cope with beams of less than 10/sup 7/ pbars, will be reviewed. Possible future developments will be sketched.

Status of the antiproton decelerator: AD

A simplified scheme for the provision of antiprotons at 100 MeV/c in fast extraction is described. The scheme uses the existing p production target area and the modified Antiproton Collector Ring in their current location. Some modifications necessary to deliver batches of 1 × 10 7 antiprotons every minute at 100 MeV/c are described, details of the machine layout and the experimental area in the existing AAC Hall are given.

Production of MeV antiprotons

In view of a future antihydrogen programme at CERN, the options for producing MeV antiprotons are revisited. The current limitations, operational performances and foreseen improvements are detailed. An alternative scheme using a dedicated machine for production and deceleration is also discussed.

Overview of the recent operation of the AAC and LEAR for the low-energy antiproton physics programme

This paper reviews the recent performance of the AAC and LEAR. Activities on the AAC include the successful exploitation of a magnetic horn as an antiproton collector lens and an energy-saving mode of operation, which has been possible since 1992, when LEAR became the only client of the AAC. LEAR worked in its full momentum range between 100 MeV/c and 2 GeV/c, with performance (intensities, ejection modes and spill length) exceeding the design specifications. Improvements are described, which contributed to the quality of the beam delivered to experiments. The reliability and availability of the antiproton machines are also discussed.

Optics for the Antiproton Decelerator at CERN

The former Antiproton Collector (AC) at CERN has been transformed into an Antiproton Decelerator (AD) to supply high quality antiproton beams with a momentum of 100 MeV/c (kinetic energy of 5.3 MeV). As in AC, antiprotons are injected at 3.57 GeV/c and cooled by stochastic cooling system. To facilitate the deceleration and to prepare a small emittance beam for the experiments, stochastic cooling at 2 GeV/c and electron cooling at 300 MeV/c and 100 MeV/c has been incorporated. The required optics modifications are described and the results of machine commissioning are discussed.

Equilibrium beam in the Antiproton Decelerator (AD)

Abstract In order to evaluate the beam quality obtained with beam cooling applied, it is important to consider possible sources of beam heating. In this paper, a theoretical study is presented of the influence of the residual gas, intra beam scattering, and other heating mechanisms, on the circulating antiprotons in the Antiproton Decelerator (AD) (S. Maury, CERN Internal Note PS/AR 96-43, 1996). From this study it has been possible to evaluate the cooling, the vacuum quality, and the control of other heating sources, necessary to achieve the design goal of a two sigma transverse emittance of 1π mm mrad at a momentum of 100 MeV /c . The calculations are compared to previous experimental studies made in the AC, and good agreement is found.

RECENT RESULTS ON LEAD-ION ACCUMULATION IN LEAR FOR THE LHC

Abstract To prepare dense bunches of lead ions for the LHC it has been proposed to accumulate the 4.2 MeV/u linac beam in a storage ring with electron cooling. A series of experiments is being performed in the low-energy ring LEAR to test this technique. First results were already reported at the Beam Crystallisation Workshop in Erice in November 1995. Two more recent runs to complement these investigations were concerned with: further study of the beam lifetime; the dependence of the cooling time on optical settings of the storage ring and on neutralization of the electron beam; and tests in view of multiturn injection. New results obtained in these two runs in December 1995 and in April 1996 will be discussed in this contribution.