Réalisations instrumentales pour le contrôle fonctionnel de l'infrastructure et des détecteurs de l'expérience ATLAS

The European Organization for Nuclear Research or CERN, Geneva, is about to operate the Large Hadron Collider (LHC). This accelerator ring and its particles detectors have been built to try to answer to the actual questions given by the particle physics theories. One of these detectors, ATLAS, has been designed, for instance, to validate, or invalidate, the theories on the existence of the Higgs Boson. The operation of the detector and the quality of its data depend on the quality of the detection elements but it depends also strongly on the good monitoring of its environment. In this respect, the developments presented in this document are focused on the control of the infrastructure of the ATLAS detector and on the ALFA detector (Absolute Luminosity For ATLAS) which is designed to provide an absolute measurement of the luminosity of the LHC beam at the ATLAS interaction point. Two projects which are integrated in the Detector Control System (DCS) are presented in the first part of the document: FPIAA (Finding Persons Inside ATLAS Areas) has been developed as a tool for people safety in the experimental cavern during the maintenance periods of ATLAS. It consists in an application for people localization and an active tracking of people in the cavern. A second application has been developed to measure the level of ionizing radiations and the particles fluency in the detector during its operation. These data will be used to eval uate the aging of the elements of the detector in respect with the level of integrated radiations. The work done on the ALFA detector is focused on particle detection technologies and control applications. The photo detection devices which will be used have been evaluated, the hardware of the trigger counter have been studied and optimized. Finally, preliminary developments on the DCS of the ALFA detector will be presented. Software components have been implemented to configure remotely the front-end electronics of the detector and to perform automated calibrations. A high level communication scheme has also been implemented for data exchange between the ALFA DCS and the system which controls the movements of the detector on the LHC beam

Hadron beam test of a scintillating fibre tracker system for elastic scattering and luminosity measurement in ATLAS

A scintillating fibre tracker is proposed to measure elastic proton scattering at very small angles in the ATLAS experiment at CERN. The tracker will be located in so-called Roman Pot units at a distance of 240 m on each side of the ATLAS interaction point. An initial validation of the design choices was achieved in a beam test at DESY in a relatively low energy electron beam and using slow off-the-shelf electronics. Here we report on the results from a second beam test experiment carried out at CERN, where new detector prototypes were tested in a high energy hadron beam, using the first version of the custom designed front-end electronics. The results show an adequate tracking performance under conditions which are similar to the situation at the LHC. In addition, the alignment method using so-called overlap detectors was studied and shown to have the expected precision.Comment: 12 pages, 8 figures. Submitted to Journal of Instrumentation (JINST

Hard Diffraction with Proton Tagging at the LHC

The main parts of the LHC diffractive physics programme possible to be measured using a proton tagging technique are presented. The geometric acceptance of the ATLAS forward proton detectors: ALFA and AFP for various LHC optics settings are shown. The probabilities of observing a proton originating from a minimum-bias event in ALFA and AFP stations are given. The main properties of single diffractive and double Pomeron exchange production of dijets, photon+jet, jet-gap-jet and W/Z bosons are discussed. The possibility of measuring the jet production in exclusive (double proton tag) and semi-exclusive (single tag) mode is evaluated

Exclusive π+π−\pi^+\pi^- Production at the LHC with Forward Proton Tagging

A process of Central Exclusive $\pi^+\pi^-$ production in proton-proton collisions and its theoretical description is presented. A possibility of its measurement, during the special low luminosity LHC runs, with the help of the ATLAS central detector for measuring pions and the ALFA stations for tagging the scattered protons is studied. A visible cross section is estimated to be 21 $\mu$b for $\sqrt{s}=7$ TeV, which gives over 2000 events for 100 $\mu$b$^{-1}$ of integrated luminosity. Differential distributions in pion pseudorapidities, pion and proton transverse momenta as well as $\pi^+\pi^-$ invariant mass are shown and discussed.Comment: 9 pages, 7 figure

Current and Nascent SETI Instruments

Here we describe our ongoing efforts to develop high-performance and sensitive instrumentation for use in the search for extra-terrestrial intelligence (SETI). These efforts include our recently deployed Search for Extraterrestrial Emissions from Nearby Developed Intelligent Populations Spectrometer (SERENDIP V.v) and two instruments currently under development; the Heterogeneous Radio SETI Spectrometer (HRSS) for SETI observations in the radio spectrum and the Optical SETI Fast Photometer (OSFP) for SETI observations in the optical band. We will discuss the basic SERENDIP V.v instrument design and initial analysis methodology, along with instrument architectures and observation strategies for OSFP and HRSS. In addition, we will demonstrate how these instruments may be built using low-cost, modular components and programmed and operated by students using common languages, e.g. ANSI C.Comment: 12 pages, 5 figures, Original version appears as Chapter 2 in "The Proceedings of SETI Sessions at the 2010 Astrobiology Science Conference: Communication with Extraterrestrial Intelligence (CETI)," Douglas A. Vakoch, Edito

Prospects and Results from the AFP Detector in ATLAS

In 2016 one arm of the AFP detector was installed and first data have been taken. In parallel with integration of the AFP subdetector into the ATLAS TDAQ and DCS systems, beam tests and preparations for the installation of the 2$^{\textrm{nd}}$ arm are performed. In this report, a status of the AFP project in the ATLAS experiment is discussed.Comment: 5 pages, 2 figures, Proceedings of the 8th International Workshop on Multiple Partonic Interactions at the LHC, Chiapas, Mexic

PYRAMIR: Calibration and operation of a pyramid near-infrared wavefront sensor

The concept of pyramid wavefront sensors (PWFS) has been around about a decade by now. However, there is still a great lack of characterizing measurements that allow the best operation of such a system under real life conditions at an astronomical telescope. In this article we, therefore, investigate the behavior and robustness of the pyramid infrared wavefront sensor PYRAMIR mounted at the 3.5 m telescope at the Calar Alto Observatory under the influence of different error sources both intrinsic to the sensor, and arising in the preceding optical system. The intrinsic errors include diffraction effects on the pyramid edges and detector read out noise. The external imperfections consist of a Gaussian profile in the intensity distribution in the pupil plane during calibration, the effect of an optically resolved reference source, and noncommon-path aberrations. We investigated the effect of three differently sized reference sources on the calibration of the PWFS. For the noncommon-path aberrations the quality of the response of the system is quantified in terms of modal cross talk and aliasing. We investigate the special behavior of the system regarding tip-tilt control. From our measurements we derive the method to optimize the calibration procedure and the setup of a PWFS adaptive optics (AO) system. We also calculate the total wavefront error arising from aliasing, modal cross talk, measurement error, and fitting error in order to optimize the number of calibrated modes for on-sky operations. These measurements result in a prediction of on-sky performance for various conditions

Forward Physics at the LHC (Elba 2010)

The papers review the main theoretical and experimental aspects of the Forward Physics at the Large Hadron Collider

Stoichiometry control of magnetron sputtered Bi2_2Sr2_2Ca1−x_{1-x}Yx_xCu2_2Oy_y (0≤\lex≤\le0.5) thin film, composition spread libraries: Substrate bias and gas density factors

A magnetron sputtering method for the production of thin-film libraries with a spatially varying composition, x, in Bi2Sr2Ca1-xYxCu2Oy (0<=x<=0.5) has been developed. Two targets with a composition of Bi2Sr2YCu2O_{8.5 + \delta} and Bi_2Sr_2CaCu_2O_{8 + \delta} are co-sputtered with appropriate masks. The target masks produce a linear variation in opposite, but co-linear radial direction, and the rotation speed of the substrate table is sufficient to intimately mix the atoms. EDS/WDS composition studies of the films show a depletion of Sr and Bi that is due to oxygen anion resputtering. The depletion is most pronounced at the centre of the film (i.e. on-axis with the target) and falls off symmetrically to either side of the 75 mm substrate. At either edge of the film the stoichiometry matches the desired ratios. Using a 12 mTorr process gas of argon and oxygen in a 2:1 ratio, the strontium depletion is corrected. The bismuth depletion is eliminated by employing a rotating carbon brush apparatus which supplies a -20 V DC bias to the sample substrate. The negative substrate bias has been used successfully with an increased chamber pressure to eliminate the resputtering effect across the film. The result is a thin film composition spread library with the desired stoichiometry.Comment: 16 pages, 12 figures, 4 tables, submitted to Physica C - Superconductivity (April 15, 2005), elsart.st