CERN Visits Thursday 13 October PM
CERN visit 1: Antiproton Decelerator (AD) [Guides: Flemming Pedersen and Tommy Eriksson]
CERN’s Antiproton Decelerator became operational in July 2000. This machine decelerates an antiproton beam of about 3 107 antiprotons from a momentum of 3.57 GeV/c to 100 MeV/c. During deceleration the beam is cooled with stochastic and electron cooling. The facility is currently in shut-down and will be restarted in 2006. The AD is also indirectly referred to in Dan Brown's best-seller 'Angels and Demons'- you can find some comments and clarifications from CERN here.
CERN visit 2: Low Energy Ion Ring (LEIR) and PS Low Level RF
LEIR [Guides: Maria Elena Angoletta and Alfred Blas]
CERN’s Low Energy Ion Ring is part of the ions-for-LHC chain. The role of LEIR is to transform a series of long (~200 μs), low-intensity ion pulses from Linac3 into short (~200 ns), high-brightness bunches using multi-turn injection, electron cooling and accumulation. From an RF viewpoint, LEIR will be equipped with two new large-bandwidth cavities based on FinemetŪ high-permeability magnetic alloy, built in collaboration with KEK. LEIR is the first CERN accelerator to be equipped with an all-digital beam control and cavity servoing system for the low-level RF, developed in collaboration with BNL.
PS Low Level RF [Guides: Jean-Luc Vallet and Stephen Hancock]
CERN's PS accelerator has been in operation for more than 45 years, and has continuously been upgraded throughout its life. It plays a central role amongst CERN's injector synchrotron as most beams used at CERN passes through the PS: protons for LHC, ions for LHC, protons for SPS for fixed target physics at the SPS, protons for East Hall near PS, protons for nTOF, protons for antiproton production. Each type of beam has particular requirements. The current generations of low level RF systems in the PS central building has been developed over the last 15 years and is permanently being upgraded to satisfy the needs of the CERN users.
CERN visit 3: LHC RF test setup in SM18 (France) [Guides: Philippe Baudrenghien and Pierre Maesen]
A facility has been set-up for testing the LHC RF. This includes a 400 MHz superconducting cavity, powered by a 300 kW klystron via a waveguide and a circulator. The nominal accelerating field is 2 MV. The klystron is driven by a prototype Low-Level RF system responsible for tuning and RF cavity feedback. Beam loading and suppression of RF phase noise from the klystrons, require sophisticated RF cavity feedback loops. The performance of these loops is limited by the open loop group delay of cables, waveguides and klystron, and the delays in the test stand are close to the delays anticipated in the final installation (~ 600 ns).