• M. Benedikt, J. Gutleber, M. Palm, W. Pirkl
  CERN, Geneva
• U. Dorda, A. Fabich
  EBG MedAustron, Wr. Neustadt

MedAustron is a synchrotron based accelerator facility for cancer treatment in Austria currently in the development phase. The design is based on the PIMMS study* and CNAO** synchrotron. In addition to the clinical application, the accelerator will also provide beams for nonclinical research in the fields of medical radiation physics, radiation biology and experimental physics with an extended proton energy range beyond medical requirements to 800 MeV. The differences to others medical accelerator-based facilities will be elaborated, specifically the used source technologies and configuration (starting up with protons (p) and carbon ions (C⁶⁺) allowing a later upgrade to ion species up to neon) and the online verification of all relevant beam parameters. The current project status is presented.

* PIMMS Proton-ion medical machine study, Bryant, Philip J (ed.) et al., CERN, 2000.
** CNAO, www.cnao.it

• K.L.F. Bane, G.V. Stupakov, U. Wienands
  SLAC, Menlo Park, California
• M. Benedikt, A. Grudiev, E. Mahner
  CERN, Geneva

In order for the LHC to reach an ultimate luminosity goal of 10³⁵, CERN is considering upgrade options for the LHC injector chain, including a new 50 GeV synchrotron of about 1.3 km length for protons and heavy ions, to be called the PS2. In this ring the proton energy is ramped from 4 GeV in 1.2 s, and the design (proton) current is 2.7 A. The present baseline of the vacuum system considers elliptical stainless steel chambers bakeable up to 300°C, various coatings to mitigate electron cloud are under study. For a bare stainless steel or Inconel chamber, the resistive wall wake alone will lead to multi-bunch instability, whereas for transverse mode coupling (TMCI), the threshold is above the design beam current, though this instability may become an issue once other impedance contributions are taken into account. A copper layer of varying thickness is shown to raise the TMCI threshold but to have relatively little effect on the multi-bunch resistive-wall growth rate unless the coating is very thick. We are also studying the effect of the copper coating on the penetration of the guide field during the energy ramp, which sets an upper limit on the allowable thickness.

• C. Heßler, W. Bartmann, M. Benedikt, B. Goddard, M. Meddahi, J.A. Uythoven
  CERN, Geneva

Within the scope of the LHC injector upgrade, it is proposed to replace the present injector chain by new accelerators, Linac4, SPL and PS2, for which new beam transfer lines are required. The beam properties and requirements for each of the lines are summarized. The original design of the beam lines has been fully reconsidered due to the very demanding constraints on the beam line layouts at the PS2 injection / extraction regions and a new straight section of the PS2 which led to a much improved beam line geometry. The relevant modifications and optics designs are described and a preliminary specification of the beam line equipment is also given.

• Y. Papaphilippou, W. Bartmann, H. Bartosik, M. Benedikt, B. Goddard, A. Lachaize
  CERN, Geneva
• Y. Senichev
  FZJ, Jülich

The PS2 ring is designed with negative momentum compaction arc cells and doublet straights. In this paper, different lattice geometries are considered. In particular, a two-fold symmetric lattice with dispersion suppressors and a 3-fold symmetric one with resonant arc cells are compared with respect to their optics properties, and ability to satisfy space and magnet constraints. The tuning flexibility of rings based on these two options is presented. Finally, the impact of different geometries on resonance excitation and dynamic aperture is evaluated.

• H. Bartosik, W. Bartmann, M. Benedikt, B. Goddard, Y. Papaphilippou
  CERN, Geneva

The PS2 lattice, based on Negative Momentum Compaction (NMC) arc cells is being optimized in order to accommodate a new all-doublet long-straight section (LSS) design. Apart from smoothing the optics and enabling different tuning solutions for H^- injection, the optimization focuses on increasing the available magnet-to-magnet drift space and reducing the quadrupole types and strengths. The variation of lattice parameters for a wide range of working points is presented.

• H. Bartosik, M. Benedikt, Y. Papaphilippou
  CERN, Geneva

This paper describes a detailed analysis of various non-linear effects of the nominal Negative Momentum Compaction lattice for PS2. Chromaticity and orbit correction schemes together with dynamic aperture studies are presented. The impact of magnet errors is being assessed and tolerances are evaluated. Frequency and diffusion maps are produced and, combined with non-linear driving terms analysis, are used for working point optimization.