Willi Kalbreier

Target Stations and Beam Dumps for the CERN SPS

The design of the absorber blocks for internal and external dumping of the SPS proton beam is discussed. In addition, the external target stations for slow and fast extracted proton beams are described.

Electrostatic Deflectors for Luminosity Measurements at the Cern pp Collider

Electrostatic deflectors are used in the CERN SPS Collider to separate the orbits of protons and antiprotons. The total installation comprises 4 tanks, 3 m long each, with a vacuum of 10-8 Pa after baking. The operating electric field is 50 kV/cm across a gap of 4 cm, between 3 m long titanium electrodes; the spark rate does not exceed 2 per 24 hours. The construction, the HV circuit, and the performances of the separators are described in this paper.

The CERN PS multi-turn extraction based on beam splittting in stable islands of transverse phase space

The PS Multi-Turn Extraction Study Group M. J. Barnes*, O. E. Berrig, A. Beuret, J. Borburgh, P. Bourquin, R. Brown, J.-P. Burnet, F. Caspers, J.-M. Cravero, T. Dobers, T. Fowler, S. Gilardoni, M. Giovannozzi (Study Group Leader), M. Hourican, W. Kalbreier, T. Kroyer, F. di Maio, M. Martini, V. Mertens, E. Métral, K.-D. Metzmacher, C. Rossi, J.-P. Royer, L. Sermeus, R. Steerenberg, G. Villiger, T. Zickler

Computerized precision control of a synchronous high voltage discharge switch for the beam separation system of the LEP e/sup +//e/sup -/ collider

Electrostatic separators are used to separate the beams in the LEP (Large Electron Positron collider). The counter-rotating beams are eventually brought into collision in the four low beta insertions, using switches to discharge simultaneously four high-voltage (HV) circuits. Each switch consists of four spark gaps mounted in a pressure vessel. A reduction of the gap widths below the self-ignition distance by electric motors results in the initiation of the discharges. Synchronization is ensured by the electrical coupling of the electrodes connected to ground. The design and performance of the computerized precision control of the discharge switch are described. The dynamic characteristics of the prototype switch are also presented. It is concluded that, with computerized precision control of the electrode motions of an HV discharge switch, it is possible to obtain better time accuracy than would have been the case with conventional analog servo feedback systems. In fact, the accuracy can be a fraction of the system time constant and allow large tolerances on the system parameters.<<ETX>>