• M. Gyr, W. Bartmann, M. Benedikt, B. Goddard, M. Meddahi
  CERN, Geneva
• A. Koschik
  ETH, Zürich
• D. Mayani Parás
  UNAM, México, D.F.

For the proposed PS2 accelerator several extraction systems are needed, including a slow third-integer resonant extraction. The requirements are presented together with the conceptual considerations for the sextupole locations and strengths, the separatrices at the extraction elements and the aperture implications for the overall machine. Calculations of the phase space separatrices have been computed with a new code for the physics of slow resonant extraction, which is briefly reviewed. Implications for the extraction equipment design and for the injection-extraction straight section optics are discussed.

• B. Goddard, W. Bartmann
  CERN, Geneva
• V.V. Danilov
  ORNL, Oak Ridge, Tennessee
• D.E. Johnson
  Fermilab, Batavia

Laser stripping for an H^- injection system into the proposed PS2 accelerator could provide an attractive alternative to the use of a conventional stripping foil. In this paper possible concepts for a 4 GeV laser stripping system are outlined and compared, using either laser or magnetic initial stripping steps and a resonant excitation of the intermediate H0 atom, followed by a final magnetic stripping. Issues of laser power, overall efficiency and emittance growth are discussed.

• J.A. Uythoven, W. Bartmann, J. Borburgh, T. Fowler, B. Goddard, M. Meddahi
  CERN, Geneva

The conceptual considerations of a fast injection system for protons and ions in the proposed PS2 accelerator are presented. Initial design parameters of the injection septum and kicker systems are derived, taking into account rise and fall times, apertures and machine optics. The requirements for an injection dump used for failures are described. Possible limitations and technical issues are outlined.

• J. Barranco
  UPC, Barcelona
• W. Bartmann, M. Benedikt, Y. Papaphilippou
  CERN, Geneva

A main concern in high intensity rings is the evaluation of uncontrolled losses and their minimization using collimation systems. A two-stage systemis foreseen for the PS2. The fundamental design strategy for the collimation design is presented, including machine apertures and collimator materials. The dependence of the collimator system efficiency on the primary scraper length and the impact parameter of the particle is evaluated for different collimator locations. Beam loss maps are finally produced displaying the detailed power load deposited around the ring.

• W. Bartmann, J. Barranco, M. Benedikt, B. Goddard, T. Kramer, Y. Papaphilippou, H. Vincke
  CERN, Geneva

Control of beam losses is an important aspect of the H^- injection system for the PS2, a proposed replacement of the CPS in the CERN injector complex. H^- ions may pass the foil unstripped or be partially stripped to excited H0 states which may be stripped in the subsequent strong-field chicane magnet. Depending on the choice of the magnetic field, atoms in the ground and first excited states can be extracted and dumped. The conceptual design of the waste beam handling is presented, including local collimation and the dump line, both of which must take into account the divergence of the beam from stripping in fringe fields. Beam load estimates and activation related requirements of the local collimators and dump are briefly discussed.

• Y. Papaphilippou, J. Barranco, W. Bartmann, M. Benedikt, C. Carli
  CERN, Geneva
• R. De Maria, S. Peggs, D. Trbojevic
  BNL, Upton, Long Island, New York

The effect of magnet misalignments in the beam orbit and linear optics functions are reviewed and correction schemes are applied to the negative momentum compaction lattices of PS2. Chromaticity correction schemes are also proposed and tested with respect to off-momentum optics properties. The impact of the correction schemes in the dynamic aperture of the different lattices is finally evaluated.

• Y. Papaphilippou, J. Barranco, W. Bartmann, M. Benedikt, C. Carli, B. Goddard
  CERN, Geneva
• R. De Maria, S. Peggs, D. Trbojevic
  BNL, Upton, Long Island, New York

In view of the CERN Proton Synchrotron proposed replacement with a new ring (PS2), a detailed optics design as been undertaken following the evaluation of several lattice options. The basic arc module consists of cells providing negative momentum compaction. The straight section is formed with a combination of FODO and quadrupole triplet cells, to accommodate the injection and extraction systems, in particular the H^- injection elements. The arc is matched to the straight section with a dispersion suppressor and matching module. Different lattices are compared with respect to their linear optics functions, tuning flexibility and geometrical acceptance properties.

• S. Aumon, W. Bartmann, S.S. Gilardoni, E. Métral, G. Rumolo, R.R. Steerenberg
  CERN, Geneva
• B. Salvant
  EPFL, Lausanne

The CERN PS crosses transition energy at about 6 GeV by using a second order gamma jump performed with special quadrupoles. However, for high-intensity beams, and in particular the single bunch beam for the neutron Time-of-Flight facility, a controlled longitudinal emittance blow-up is still needed to prevent a fast single-bunch vertical instability from developing near transition. A series of studies have been done in the PS in 2008 to measure the beam behaviour near transition energy for different settings of the gamma transition jump. The purpose of this paper is to compare those measurements with simulations results from the HEADTAIL code, which should allow to understand better the different mechanisms involved and maybe improve the transition crossing.