Laser Stripping for the PS2 Charge-Exchange Injection System

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

4 GeV H- Charge Exchange Injection into the PS2

The proposed PS2 will accelerate protons from 4 to 50 GeV. The required beam intensity and brightness can only be achieved with a multi-turn H- charge exchange injection system, where the small emittance injected beam is used to paint the transverse phase space of the PS2 machine. This paper describes the constraints and conceptual design of the H- injection system and its incorporation into the present PS2 lattice. The requirements for the special injection system elements are described, in particular the injection chicane and painting magnet systems and the change exchange foil. Some key performance aspects are investigated, including the stripping efficiency, expected emittance growth and beam loss arising from the simulated number of multiple foil traversals, together with estimates of foil heating

PS2 Injection, Extraction and Beam Transfer Concepts

The replacement of CERN's existing 26 GeV Proton Synchrotron (PS) machine with a separated-function synchrotron PS2 has been identified as an important part of the possible future upgrade programme of the CERN accelerator complex. The PS2 will require a number of new beam transfer systems associated with injection, extraction, beam dumping and transfer. The different requirements are briefly presented, together with an overview of the conceptual design of these systems, based on the initial PS2 parameter set. The required equipment sub-system performance is derived and discussed. Possible limitations are analysed and the impact on the overall design and parameter set is discussed

Fast Injection into the PS2

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

Retinal nerve fibre layer thinning is associated with drug resistance in epilepsy.

Retinal nerve fibre layer (RNFL) thickness is related to the axonal anterior visual pathway and is considered a marker of overall white matter 'integrity'. We hypothesised that RNFL changes would occur in people with epilepsy, independently of vigabatrin exposure, and be related to clinical characteristics of epilepsy

Beam Loss Control for the Unstripped Ions from the PS2 Charge Exchange Injection

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

Resonant Third-Integer Extraction from the PS2

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

Optics Considerations for the PS2

CERN envisages replacing the existing Proton Synchrotron (PS) with a larger synchrotron (PS2) capable of injecting at higher energy into the SPS. Since it should increase the performance not only of the LHC but also CNGS and other users of beams from CERN's hadron injector complex, the new accelerator must retain much of the flexibility of the present complex. A number of candidate optics, with and without transition crossing, have been evaluated systematically and compared

Linear Optics Design for PS2

The design considerations and key parameters for the replacement of the CERN Proton Synchrotron (PS) with a new ring (PS2), as part of the upgrade of the LHC injector complex are summarized. Classical linear optics solutions including standard FODO, doublet and triplet cells with real transition energy, are studied. Particular emphasis is given to the tuning and optimisation of Negative Momentum Compaction (NMC) cells with imaginary transition energy. The optics of the high energy transfer line is also presented

Linear optics design of negative momentum compaction lattices for PS2

In view of the CERN Proton Synchrotron proposed replacement with a new ring (PS2), a detailed optics design has 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