Consolidation project of the electrostatic septa in the CERN PS ring

After almost two decades of reliable service, the electrostatic septa of the CERN PS complex need to be upgraded. This is to fulfil the increased requirements on vacuum performance and the need to reduce the time spent on maintenance interventions. Two electrostatic septa are used in the PS ring: septum 23 is used for a resonant slow extraction, while septum 31 is used for the so-called 'continuous transfer' (CT) 5-turn extraction. This paper describes the experience gained with these septa over the years. We report the main characteristics and technological advantages of the new septum 23 together with its present performance

A new set of magnetic septa in the CERN PS complex

Over the last few years the CERN PS Complex has been upgraded to fulfill the requirements of two major projects : (i) - producing and transferring lead ions to the SPS for high energy physics experiments and (ii) raising the PSB to PS transfer energy from 1 to 1.4 GeV to generate the high brightness beam for the LHC. To cope with the tight demands imposed by these upgrades, ten magnetic septa, operating under vacuum in the PSB and the PS have been redesigned and progressively replaced. The new devices are bakeable, better suited to high vacuum operation and with higher performance. This paper reports the main characteristics and technological advantages of these magnets together with their present performance

The Pulsed Power Converter and Septum Magnet System for Injection into the Electron Storage Ring at ESRF

At ESRF, the European Synchrotron Radiation Facility in Grenoble, electrons are accelerated, via a 200 MeV Linac and a 6 GeV synchrotron booster, and injected into the storage ring at 10 Hz rate. Two thin septum blade magnets and an eddy current sheet type septum magnet provide the final deflection of the injected beam. The operational requirements of the e- injection scheme and the resulting demanding hardware specifications are recalled. The pulsed septum magnets are briefly described. The design, circuit layout and construction of the power converters are related with emphasis on innovative aspects of general interest. Results of tests during commissioning are reported

From urn models to zero-range processes: statics and dynamics

The aim of these lecture notes is a description of the statics and dynamics of zero-range processes and related models. After revisiting some conceptual aspects of the subject, emphasis is then put on the study of the class of zero-range processes for which a condensation transition arises.Comment: Lecture notes for the Luxembourg Summer School 200

Acceleration of lead ions in the CERN PS booster and the CERN PS

The new CERN Heavy Ion Accelerating Facility also requires besides a new Linac substantial modifications of existing accelerators. They are imposed by the low speed and the low intensity of the ion beam and, crucially at low energy, by the short lifetime of the partially stripped ions due to charge exchange with the atoms of the residual gas. The upgraded vacuum system hits the limits of a non-bakeable machine and consequently the acceleration had to be sped up by all means. In the Booster this led to injection and RF capture on a fast-rising magnet cycle and a new digital RF beam control system. Beam current transformers had to be replaced by new, heavily shielded ones. Other modifications include a new staircase magnet to distribute ions over the four Booster rings, lengthening of septa and kicker pulses, plus new, bakeable extraction septa and an energy stabilizing RF loop on the flat top in the CPS, and a stripper in the transfer line to the SPS

Nonequilibrium Statistical Mechanics of the Zero-Range Process and Related Models

We review recent progress on the zero-range process, a model of interacting particles which hop between the sites of a lattice with rates that depend on the occupancy of the departure site. We discuss several applications which have stimulated interest in the model such as shaken granular gases and network dynamics, also we discuss how the model may be used as a coarse-grained description of driven phase-separating systems. A useful property of the zero-range process is that the steady state has a factorised form. We show how this form enables one to analyse in detail condensation transitions, wherein a finite fraction of particles accumulate at a single site. We review condensation transitions in homogeneous and heterogeneous systems and also summarise recent progress in understanding the dynamics of condensation. We then turn to several generalisations which also, under certain specified conditions, share the property of a factorised steady state. These include several species of particles; hop rates which depend on both the departure and the destination sites; continuous masses; parallel discrete-time updating; non-conservation of particles and sites.Comment: 54 pages, 9 figures, review articl

Conversion of the PS complex as LHC proton pre-injector

CERNs Large Hadron Collider (LHC) [1][2] will be supplied with protons from the injector chain Linac2-PS Booster (PSB)-PS-SPS (Fig. 1). The required transverse beam brilliance (intensity/emittance) is almost twice that of current PS beams and the LHC bunch spacing of 25 ns must be impressed on the beam before its transfer to the SPS. The scheme involves new RF harmonics in the PSB and the PS, an increase of the PSB energy, and two-batch filling of the PS. After a successful test of the main ingredients, a project for converting the PS complex was launched in 1994. Major additions are (i) h=1 RF systems in the PSB, (ii) upgrading of the PSB main magnet supply from 1 to 1.4 GeV operation, (iii) new magnets, septa, power supplies, kicker pulsers for the PSB-PS beam transfer, (iv) 40 and 80 MHz systems in the PS, (v) beam profile measurement devices with improved resolution. A significant part of the effort is being provided by TRIUMF under the Canada-CERN co-operation agreement on the LHC

The PS complex produces the nominal LHC beam

The LHC [1] will be supplied, via the SPS, with protons from the pre-injector chain comprising Linac2, PS Booster (PSB) and PS. These accelerators have under-gone a major upgrading programme [2] during the last five years so as to meet the stringent requirements of the LHC. These imply that many high-intensity bunches of small emittance and tight spacing (25 ns) be available at the PS extraction energy (25 GeV). The upgrading project involved an increase of Linac2 current, new RF systems in the PSB and the PS, raising the PSB energy from 1 to 1.4 GeV, two-batch filling of the PS and the installation of high-resolution beam profile measurement devices. With the project entering its final phase and most of the newly installed hardware now being operational, the emphasis switches to producing the nominal LHC beam and tackling the associated beam physics problems. While a beam with transverse characteristics better than nominal has been obtained, the longitudinal density still needs to be increased. An alternative scheme to produce the 25 ns bunch spacing is outlined, together with other promising developments