Search for non-Gaussian events in the data of the VIRGO E4 engineering run

International audienc

The Virgo data acquisition system

International audienc

The gravitational wave detector VIRGO

International audienc

LS1 “First Long Shutdown of LHC and its Injector Chains”

The LHC and its Injectors were stopped in February 2013, in order to maintain, consolidate and upgrade the different equipment of the accelerator chain, with the goal of achieving LHC operation at the design energy of 14 TeV in the centre-of-mass. Prior to the start of this First Long Shutdown (LS1), a major effort of preparation was performed in order to optimize the schedule and the use of resources across the different machines, with the aim of resuming LHC physics in early 2015. The rest of the CERN complex will restart beam operation in the second half of 2014. This paper presents the schedule of the LS1, describes the organizational set-up for the coordination of the works, the main activities, the different main milestones, which have been achieved so far, and the decisions taken in order to mitigate the issues encountered

Work effort in the LHC injector complex for the upgrade scenarios

This document describes the work in the PSB, PS and SPS that is required for upgrade scenario 1. It will be shown that the requirements on the hardware work needed for upgrade scenario 1 are identical to the ones of the upgrade scenario 2 [1]. The various activities are detailed as well as their dependencies and an estimate given for the duration of the necessary shutdowns and recommissioning periods with beam. It is mentioned whether some decisions are still to be taken and are related to information to be obtained after LS1. Another important aspect is the evaluation of the risks related to the upgrade interventions and operational complexity, which concern schedule, beam characteristics as well as reliability and overall performance. It has been studied if part of the activities could be spread out over several machine stops, and as conclusion the preferred scenario will be presented

CERN Proton Synchrotronworking point Matrix for extended pole face winding powering scheme

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 momenta, resulted in matrices defining the relationship between the five pole face winding currents and the four beam parameters Qh, Qv, h, and v. Each cell of these matrices was fitted against momentum. The final result is a single matrix as a function of beam momentum, 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

Studies and implementation of the PS dummy septum to mitigate irradiation of magnetic septum in straight section 16

During the commissioning phase of the PS Multi-Turn Extraction (MTE) and the following operational period a number of limitations were observed, namely activation of the magnetic septum in straight section 16, fluctuation of the fraction of particles trapped in the islands, and instabilities of the injection trajectories in the SPS. These issues have been addressed in many ways, by either dedicated measurement campaigns or paper studies to determine mitigation measures. In this document the proposed solution of installing a dummy septum in straight section 15 of the PS ring to reduce the activation of the extraction magnetic septum is described in details

The PS upgrade programme: Recent advances

The LHC Injectors Upgrade project (LIU) has been initiated to improve the performances of the existing injector complex at CERN to match the future requirements of the HL-LHC (High Luminosity LHC). In this framework, the Proton Synchrotron (PS) will undergo fundamental changes for many of its main systems: The injection energy will be increased to reduce space-charge effects, the transverse damper will be improved to cope with transverse instabilities, and the RF systems will be upgraded to accelerate higher beam intensity and brightness. These hardware improvements are triggered by a series of studies meant to identify the most critical performance bottlenecks, like space charge, impedances, longitudinal and transverse instabilities, as well as electron-cloud. Additionally, alternative production schemes for the LHC-type beams have been proposed and implemented to circumvent some of the present limitations. A summary of the most recent advances of the studies, as well as the proposed hardware improvements is given. Copyright © 2013 by JACoW

Status of Virgo

We report on the status of the VIRGO detector as of the beginning of 2003. In particular, we summarize the results obtained during the commissioning of the central portion of the detector, consisting of a power-recycled Michelson interferometer, and we outline the steps which will lead during 2003 and 2004 to the commissioning and operation of the full scale, 3 km long VIRGO detector

Data analysis methods for non-Gaussian, nonstationary and nonlinear features and their application to VIRGO

The commissioning of the VIRGO central interferometer occasioned the implementation and tests of various algorithms for the characterization of the non-Gaussianity, non-stationarity and non-linearity of the dark fringe data. This library of prototypes will serve as groundwork for the near commissioning of VIRGO (full scale). We make a summary of the activities on that subject including the description of the selected algorithms and some results obtained with the data of the engineering runs