The CERN Antiproton Decelerator (AD) Operation, Progress and Plans for the Future

The CERN Antiproton Decelerator (AD) is a simplified source providing low energy antiprotons for experiments, replacing four machines: AC (Antiproton Collector), AA (Antiproton Accumulator), PS and LEAR (Low Energy Antiproton Ring), shut down in 1996. The former AC was modified to include deceleration, electron cooling and ejection lines into the new experimental area. The AD started physics operation in July 2000 and has since delivered cooled beams at 100 MeV/c (kinetic energy of 5.3 MeV) to 3 experiments (ASACUSA, ATHENA and ATRAP). Problems encountered during the commissioning and the physics runs will be outlined as well as progress during 2001 and possible future developments

LEIR lattice

The Low Energy Ion Ring (LEIR) is a low energy ion cooling and accumulation ring and serves to compress long ion pulses from Linac3 into high density bunches suitable for LHC ion operation. Issues of the LEIR lattice are to fulfil all constraints with a small number of quadrupoles and compensations of perturbations due to an electron cooler and gradients seen by the beam in the bending magnets during the ramp. Furthermore, experimental investigations via orbit response measurements will be reported

Beam optics issues for the antiproton decelerator

The deceleration of the beam down to 0.1 GeV/c in the ring previously used as Antiproton Collector (AC) at 3.5 GeV/c, requires a number of modifications to the lattice. The insertion of the electron cooling, needed to cool the antiproton beam at low energy, implies the re-arrange-ment of quadrupoles. The optical functions then need to be readjusted in order to keep the large acceptance and to cope with the electron and stochastic cooling environ-ment. Calculations of the linear optics and of the accep-tance are reported. Tests of beam deceleration in the AC show the need for closed-orbit correction at low momentum in addition to the static correction by the movement of the quadrupoles available in the present configuration. The deceleration tests will be discussed and a correction system, which includes trim supplies on the main bending magnets, will be described

Hadron Coolers at CERN

To provide efficient deceleration and to produce antiproton beam with the required characteristics two different cooler systems (stochastic and electron) are used in operation on the AD (Antiproton Decelerator) machine. In a near future, an electron cooling system will be used in LEIR (Low Energy Ion Ring) to accumulate ions for LHC. This system will be used for a fast ion beam cooling and stacking. These cooling systems are described

Two years of AD operation: Experience and progress

The antiproton decelerator (AD) has been running successfully for physics for the past two years. After the end of the commissioning period [1] that finished in 2000, the machine has gradually been improved. The main efforts were concentrated on increasing the beam intensity, reducing the cycle length and improving the machine stability. The intensity of the injected beam has been significantly increased due to a higher beam intensity from the PS complex and also due to increased transverse acceptances in the AD machine. The beam losses during deceleration were reduced from 30-40 % down to a few percent, mainly due to improvements of the operation of the deceleration RF cavity. Altogether these improvements increased the intensity of the ejected beam by a factor of two. Improvements of the electron cooling were followed by a reduction of emittances and cycle duration (about 15%). Progress in beam diagnostics now allows the monitoring of the machine performance during the whole cycle. The stability of the machine at the ejection momentum 100 MeV/c remains a crucial point and the identification of the causes of fluctuations in the ejected beam parameters are now under investigation

LEIR Commissioning

The Low Energy Ion Ring (LEIR) is a central piece of the injector chain for LHC ion operation, transforming long Linac 3 pulses into high density bunches needed for LHC. LEIR commissioning is scheduled to be completed at the time of the conference. A review of LEIR commissioning highlighting expected and unexpected problems and actions to tackle them will be given

ELENA, a preliminary cost and feasibility study

To produce dense pbar beams at very low energies (100-200 keV), a small decelerator ring could be built and installed between the existing AD ring and the experimental area. Phase-space blowup during deceleration would be compensated by electron cooling in order to obtain final emittances comparable to the 5MeV beam presently delivered by the AD. This report describes preliminary machine parameters and layout of ELENA and also gives an approximate estimate of cost and manpower needs

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´105pbars /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 107 pbars, will be reviewed. Possible future developments will be sketche

Ions for LHC: Towards Completion of the Injector Chain

The commissioning of CERN's ion injector complex [1] to allow 1.1 PeV collisions of ions in LHC is well under way. After the Low Energy Ion Ring (LEIR) in 2005 [2] and the Proton Synchrotron (PS) in 2006 [3], the Super Proton Synchrotron (SPS) has now been commissioned with the 'Early' ion beam, which should give a luminosity of $5×10^{25}cm^{-2}s^{-1}$ in the LHC. This paper summarizes the operation in 2007 of all the machines involved in the ion injection chain

ELENA project status

The Extra Low Energy Antiproton ring (ELENA) is a small ring at CERN which will be built to increase substantially the number of usable antiprotons delivered to the experiments for studies with antihydrogen and antiprotonic nuclei. The project is now at stage of finishing the technical design. This presentation reviews the major features of ELENA: the ring, transfer lines and experimental area layout, the choice of the basic machine parameters and the main challenges. Electron cooling plays a key role in ELENA both for efficient deceleration as well as for preparing extracted beam with parameters defined by the experiments. The choice of machine optics as a tool for achieving the required parameters and fitting the available space is discussed. The important systems like the magnets, vacuum, beam instrumentations and others are reviewed as well