• S. Hancock, C. Carli, J.F. Comblin, A. Findlay, K. Hanke, B. Mikulec
  CERN, Geneva

Since the CERN PS Booster cannot simultaneously provide the beam brightness and intensity required, the nominal (25ns bunch spacing) proton beam for the LHC involves double-batch filling of the PS machine. Linac 4, which is under construction, will eventually remove this restriction. In the meantime, the request for 50 and 75ns bunch spacings to mitigate electron cloud effects has lowered the intensity demand such that the Booster can meet this in a single batch without compromising beam brightness. Single-batch transfer means providing two bunches from each of three Booster rings and, in turn, that the bunch spacing is modified by the addition of an h=1 rf component to the h=2 in the Booster in order to fit the h=7 rf buckets waiting in the PS (whilst leaving one bucket empty for kicker purposes). Following the first experiments performed in 2008, the rf manipulations in the Booster have been refined and those in the PS have been modified to cope with single-batch beams. This latest work is presented for both the 50 and 75ns variants.

• K. Hanke, C. Carli, R. Garoby, F. Gerigk, A.M. Lombardi, S. Maury, C. Rossi, M. Vretenar
  CERN, Geneva

The construction of Linac4, a 160 MeV H^- Linac, is the first step in upgrading the LHC injector chain. Unlike CERN's present injector linac, Linac4 will inject into the subsequent synchrotron via charge exchange injection. In a first stage, it will inject into the existing CERN PS Booster. At a later stage, Linac4 has the option to be extended by a superconducting linac (SPL) which could then inject into a new synchrotron (PS2). Construction of Linac4 has started in 2008, and beam operation is presently planned for 2014. An overview of the Linac4 main parameters and design choices is given, and the status of the construction reported.

• P. Freyermuth, D.G. Cotte, M. Delrieux, H. Genoud, S.S. Gilardoni, K. Hanke, O. Hans, S. Mataguez, G. Metral, F.C. Peters, R.R. Steerenberg, B. Vandorpe
  CERN, Geneva

The CERN Proton Synchrotron has been continuously improving its beam performances since 1959. The working point parameters of the accelerator are mainly controlled by dedicated windings installed on the poles of the main combined function magnets. In 2007, the power supplies of these windings were renovated and extended from three to five independent groups, allowing exploration of new working point settings. This configuration offers the flexibility of several adjustment strategies such as leaving one current free or to control an additional physical parameter, like Q''_h. A non-linear chromaticity measurement campaign, at different beam energies, resulted in matrices defining the relationship between the five pole face winding currents and the four beam parameters Q_h, Q_v, Xi_h, and Xi_v. Each cell of these matrices was fitted against energy. The final result is a single matrix which is now used by the operational software to trim the working point. This paper summarises this measurement campaign by presenting the resulting matrix with a brief overview of the adjustment tools and strategy. Furthermore a few future possible benefits of this control enhancement will be discussed.