A high resolution cavity BPM for the CLIC Test Facility

In frame of the development of a high resolution BPM system for the CLIC Main Linac we present the design of a cavity BPM prototype. It consists of a waveguide loaded dipole mode resonator and a monopole mode reference cavity, both operating at 15 GHz, to be compatible with the bunch frequencies at the CLIC Test Facility. Requirements, design concept, numerical analysis, and practical considerations are discussed.Comment: 5 pp. 14th Beam Instrumentation Workshop (BIW10) 2-6 May 2010. Santa Fe, New Mexic

The magnetic model of the LHC in the early phase of beam commissioning

The relation between field and current in each family of the Large Hadron Collider magnets is modelled with a set of empirical equations (FiDeL) whose free parameters are fit on magnetic measurements. They take into account residual magnetization, persistent currents, hysteresis, saturation, decay and snapback during initial part of the ramp. Here we give a first summary of the reconstruction of the magnetic field properties based on the beam observables (orbit, tune, coupling, chromaticity) and a comparison with the expectations. The most critical issues for the machine performance in terms of knowledge of the relation magnetic field vs current are pointed out.peer-reviewe

Methamphetamine-Induced Dopamine-Independent Alterations in Striatal Gene Expression in the 6-Hydroxydopamine Hemiparkinsonian Rats

Unilateral injections of 6-hydroxydopamine into the medial forebrain bundle are used extensively as a model of Parkinson's disease. The present experiments sought to identify genes that were affected in the dopamine (DA)–denervated striatum after 6-hydroxydopamine-induced destruction of the nigrostriatal dopaminergic pathway in the rat. We also examined whether a single injection of methamphetamine (METH) (2.5 mg/kg) known to cause changes in gene expression in the normally DA-innervated striatum could still influence striatal gene expression in the absence of DA. Unilateral injections of 6-hydroxydopamine into the medial forebrain bundle resulted in METH-induced rotational behaviors ipsilateral to the lesioned side and total striatal DA depletion on the lesioned side. This injection also caused decrease in striatal serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels. DA depletion was associated with increases in 5-HIAA/5-HT ratios that were potentiated by the METH injection. Microarray analyses revealed changes (± 1.7-fold, p<0.025) in the expression of 67 genes on the lesioned side in comparison to the intact side of the saline-treated hemiparkinsonian animals. These include follistatin, neuromedin U, and tachykinin 2 which were up-regulated. METH administration caused increases in the expression of c-fos, Egr1, and Nor-1 on the intact side. On the DA-depleted side, METH administration also increased the expression of 61 genes including Pdgf-d and Cox-2. There were METH-induced changes in 16 genes that were common in the DA-innervated and DA-depleted sides. These include c-fos and Nor-1 which show greater changes on the normal DA side. Thus, the present study documents, for the first time, that METH mediated DA-independent changes in the levels of transcripts of several genes in the DA-denervated striatum. Our results also implicate 5-HT as a potential player in these METH-induced alterations in gene expression because the METH injection also caused significant increases in 5-HIAA/5-HT ratios on the DA-depleted side

The ATLAS Transition Radiation Tracker (TRT) proportional drift tube: design and performance

A straw proportional counter is the basic element of the ATLAS Transition Radiation Tracker (TRT). Its detailed properties as well as the main properties of a few TRT operating gas mixtures are described. Particular attention is paid to straw tube performance in high radiation conditions and to its operational stability

The ATLAS TRT electronics

The ATLAS inner detector consists of three sub-systems: the pixel detector spanning the radius range 4cm-20cm, the semiconductor tracker at radii from 30 to 52 cm, and the transition radiation tracker (TRT), tracking from 56 to 107 cm. The TRT provides a combination of continuous tracking with many projective measurements based on individual drift tubes (or straws) and of electron identification based on transition radiation from fibres or foils interleaved between the straws themselves. This paper describes the on and off detector electronics for the TRT as well as the TRT portion of the data acquisition (DAQ) system

Détection acoustiques des avalanches. Site La Sionne-Anzère, Valais, Suisse

Automatic detection methods are necessary to overcome difficulties inherent to the practical state of the art human obersation, which is conditioned by the presence of observers and has severe limitations due to weather, lack of visibility at night, masking reliefs's, avalanche types, etc. Seismic and acoustic techniques are considered. To test the acoustic detection method, an experimental system was installed in-situ during 94-95 winter in order to record acoustic events during periods of artificial release of avalanches. The experimentation has shown that the movement of avalanches produces acoustic signals suitable for automatic detection and localisation over extended areas. The present experimental system consists of four outside weatherproofed microphones combined in such a way as to constitue an acoustic goniometer. An additional very low noise microphone - dedicated to the record of the acoustic signatures of avalanches - completes the instrumentation. The article describes the results of the first experimental campaign, the intrinsic limits of the method - range, wind effects - and the potential of the system ARFANG to evolve in an operational way-optimisation of sound detection, automatic identification of events. / Actuellement, la seule méthode pratiquée est l'observation visuelle - impossible de nuit ou par mauvais temps. En vue de disposer dans le futur de systèmes opérationnels de mesure automatique de l'activité avalancheuse, les techniques de détection sismique et/ou acoustique sont envisagées. Pour évaluer la détection acoustique, un système expérimental a été installé sur le site de La Sionne afin d'enregistrer, durant tout l'hiver 94-95, les sons lors de déclenchements artificiels d'avalanches. L'expérience a permis de constater l'émission d'infrasons par les avalanches et a démontré la possibilité d'utiliser ces signaux pour détecter et localiser automatiquement les avalanches se produisant dans un rayon de plusieurs kilomètres. Le sytème comportait quatre microphones identiques installés de manière permanente en extérieur et reliés à une instrumentation de sorte à former un goniomètre acoustique. Un microphone extérieur supplémentaire - à très faible bruit - était utilisé exclusivement pour l'enregistrement des signatures acoustiques. L'article décrit les résultats de la 1ère campagne de mesures, les possibilités et limites de la méthode, et les perspectives d'évolution du système expérimental en un système opérationnel

Upgrade of the CERN Proton Synchrotron Booster bending magnets for 2 GeV Operation

Since its first operation in 1972 at an energy of 800MeV the CERN Proton Synchrotron Booster, which consists of 4 super imposed synchrotrons, has seen two upgrades: once to 1.0 GeV in 1988 and then to 1.4 GeV in 1999. During this time the main magnets of the machine have remained largely unchanged with small differences (<1%) between the inner and outer gaps of the main bending magnet fields being compensated by trim power supplies. The future upgrade of the machine will demand to extract protons at an energy of 2.0 GeV and require almost double the original dipole field. At this field, due to saturation effects, the inner and outer gaps of the main dipole magnets will differ by up to 4%. This paper presents the design and implementation of a modification of the magnetic circuit strongly reducing these effects. We also discuss the results of experimental tests concerning the effects on field quality and eddy current transients, including the implications for the real-time magnetic field measurement system to control RF and power supplies