The new servo-spill power converter of the CERN SPS machine

The so-called servo-spill system of the SPS machine requires a very specific power converter to be used as the power actuator of the system. Due to this particular function, the main performance required, for this power converter, is an unusual large signal current bandwidth of up to 1.5 kHz. The procurement is based on a similar industrial product using switch mode technology. This paper describes the main power part as well as the control approach chosen to fulfil the specific requirements of this power converter. Final operational results are also presented

Proposal to Increase the LEP Energy with Horizontal Orbit Correctors

In an e+ e- collider the beam energy depends only on the bending field integral "Bds while the synchrotron radiation power scales with "B2ds and is sensitive to the details of the field distribution. With fixed RF acceleration voltage it is thus possible to attain higher energies by increasing the effective bending magnet length. We propose to use the horizontal orbit correctors to exploit this effect. To control the orbit perturbations, 79 unused correctors in the regular arcs and 14 unused correctors in the dispersion suppressors will have to be powered. An energy increase of approximatively 0.18 GeV per beam might be obtained

Rejets radioactifs et environnement du CERN en 2003

La radioactivité de l’environnement autour de l’Organisation Européenne pour la Recherche Nucléaire (CERN) et les doses de rayonnements qui en résultent pour la population avoisinante sont contrôlées par la Commission de Sûreté du CERN et de manière indépendante par les autorités compétentes des deux Etats Hôtes, l’Institut de Radioprotection et de Sûreté Nucléaire (IRSN) côté France et l’Office Fédéral de la Santé Publique (OFSP) côté Suisse. Dans ce rapport, les résultats de mesures concernent en particulier le territoire suisse. L’ensemble des mesures effectuées en 2003 prouve que le fonctionnement des installations du CERN était sans conséquence radiologique sur l’environnement et la population. Le contrôle des émissions montre que les rejets effectifs se situent également en 2003 nettement en dessous des limites réglementaires. Ce constat est confirmé par le contrôle des immissions dans l’environnement. Le CERN a bien respecté en 2003 comme dans les années précédentes la valeur directrice de dose liée à la source fixée à 0.3 mSv/an. L’impact réel représente en fait moins de 10% de cette valeur, comme l’indique l’estimation pour le groupe critique, qui est de l’ordre de 0.03 mSv/an

Prevalence of <i>Anaplasma phagocytophilum</i> and <i>Coxiella burnetii</i> in <i>Ixodes ricinus</i> ticks in Switzerland: an underestimated epidemiologic risk.

Ticks are vectors of several microorganisms responsible for infectious diseases in human and animals, such as &lt;i&gt;Anaplasma phagocytophilum&lt;/i&gt; and &lt;i&gt;Coxiella burnetii.&lt;/i&gt; In this study, we investigated the prevalence of these two bacteria in 62 889 &lt;i&gt;Ixodes ricinus&lt;/i&gt; ticks in selected regions covering all Switzerland. A high prevalence of 11.9% of &lt;i&gt;A. phagocytophilum&lt;/i&gt; DNA was observed by real-time PCR on 8534 pools of ticks. This pool prevalence corresponds to an estimated prevalence of 1.71% in individual tick. A total of 144 of the 171 collection sites (84.2%) were positive for the presence of &lt;i&gt;A. phagocytophilum,&lt;/i&gt; and these sites were homogenously distributed throughout Switzerland. Such prevalence and geographical distribution underline the risk of human and animal exposure to &lt;i&gt;A. phagocytophilum&lt;/i&gt; and highlight the need to assess the epidemiology and clinical diagnosis of human and animal anaplasmosis in Switzerland. However, DNA of &lt;i&gt;C. burnetii&lt;/i&gt; was never found in any tick pool. This absence suggests a very low role of &lt;i&gt;I. ricinus&lt;/i&gt; ticks as vector and reservoir of &lt;i&gt;C. burnetii&lt;/i&gt; in Switzerland, and it supports previous reports demonstrating the role of sheep and goats in the epidemiology of Q fever. However, considering its pathogenic potential, it is necessary to keep monitoring for the possible reemergence of this bacterium in ticks in the future

ELENA, a preliminary cost and feasibility study

To produce dense pbar beams at very low energies (100-200 keV), a small decelerator ring could be built and installed between the existing AD ring and the experimental area. Phase-space blowup during deceleration would be compensated by electron cooling in order to obtain final emittances comparable to the 5MeV beam presently delivered by the AD. This report describes preliminary machine parameters and layout of ELENA and also gives an approximate estimate of cost and manpower needs

IONS FOR LHC: STATUS OF THE INJECTOR CHAIN

The LHC will, in addition to proton runs, be operated with Pb ions and provide collisions at energies of 5.5 TeV per nucleon pair, i.e. more than 1.1 PeV per event, to experiments. The transformation of CERN's ion injector complex (Linac3-LEIR-PS-SPS) to allow collision of ions in LHC in 2008 is well under way. The status of these modifications and the latest results of commissioning will be presented. The remaining challenges are reviewed

Installation and Hardware commissioning of the Multi-Turn extraction at the CERN proton synchrotron

The implementation of the new Multi-Turn Extraction (MTE) at the CERN Proton Synchrotron required major hardware changes for the nearly 50-year old accelerator. The installation of new Pulse Forming Networks (PFN) and refurbished kicker magnets for the extraction, new sextupole and octupole magnets, new power converters, together with an in-depth review of the machine aperture leading to the design of new vacuum chambers was required. As a result, a heavy programme of interventions had to be scheduled during the winter shut-down 2007-8. The newly installed hardware and its commissioning is presented and discussed in details

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

Since 2001 considerable effort has been devoted to the study of a possible replacement of the continuous-transfer extraction mode from the PS to the SPS. Such an approach, called Multi-Turn Extraction (MTE), is based on capture of the beam inside stable islands of transverse phase space, generated by sextupoles and octupoles, thanks to a properly chosen tune variation. Both numerical simulations and measurements with beam were performed to understand the properties of this new extraction mode. The experimental study was completed at the end of 2004 and by the end of 2005 a scheme to implement this novel approach in the PS machine was defined and its performance assessed. This design report presents the outcome of the studies undertaken both in terms of technical issues as well as of resources necessary to implement the proposed scheme

The energy calibration of LEP in the 1993 scan

This report summarizes the procedure for providing the absolute energy calibration of the LEP beams during the energy scan in 1993. The average beam energy around the LEP ring was measured in 25 calibrations with the resonant depolarization technique. The time variation of this average beam energy is well described by a model of the accelerator based on monitored quantities. The absolute calibration of the centre of mass energies of the off-peak points is determined with a precision of 2 parts in 10(5) resulting in a systematic error on the Z-mass of about 1.4 MeV and on the Z-width of about 1.5 MeV