The Interface and Control System of the Upgraded HVOpto/HVRemote Card of the TileCal

To comply with the increase in luminosity of the LHC (Large Hadron Collider) in the next decades, the electronics of the ATLAS (A Toroidal LHC Apparatus) experiment is being upgraded. Included in the upgrade is the interfacing and control electronics system of the HVOpto/HVRemote cards in the TileCal (Tile Calorimeter) detector, which provides high voltages to about 104 photomultipliers (PMTs). This paper presents the new interfacing architecture for the system and details the design of a prototype control board (HVRemote-Ctrl) used for test and validation of the new architecture. The tests evaluate the system multiplexing capabilities needed to monitor all the TileCal PMTs in real time. The communication channels involved, supported in Ethernet and SPI interfaces/protocols, have been fully tested. Some results from the tests already completed are presented

The LED and fiber based calibration system for the photomultiplier array of SNO+

A new external LED/fiber light injection calibration system was designed for the calibration and monitoring of the photomultiplier array of the SNO+ experiment at SNOLAB. The goal of the calibration system is to allow an accurate and regular measurement of the photomultiplier array's performance, while minimizing the risk of radioactivity ingress. The choice in SNO+ was to use a set of optical fiber cables to convey into the detector the light pulses produced by external LEDs. The quality control was carried out using a modified test bench that was used in QC of optical fibers for TileCal/ATLAS. The optical fibers were characterized for transmission, timing and angular dispersions. This article describes the setups used for the characterization and quality control of the system based on LEDs and optical fibers and their results.Peer Reviewe

The ALFA Roman Pot Detectors of ATLAS

The ATLAS Roman Pot system is designed to determine the total proton-proton cross section as well as the luminosity at the Large Hadron Collider (LHC) by measuring elastic proton scattering at very small angles. The system is made of four Roman Pot stations, located in the LHC tunnel in a distance of about 240 m at both sides of the ATLAS interaction point. Each station is equipped with tracking detectors, inserted in Roman Pots which approach the LHC beams vertically. The tracking detectors consist of multi-layer scintillating fibre structures read out by Multi-Anode-Photo-Multipliers.Peer Reviewe

The Interface and Control System of the Upgraded HVOpto/HVRemote Card of the TileCal

To comply with the increase in luminosity of the LHC (Large Hadron Collider) in the next decades, the electronics of the ATLAS (A Toroidal LHC Apparatus) experiment is being upgraded. Included in the upgrade is the interfacing and control electronics system of the HVOpto/HVRemote cards in the TileCal (Tile Calorimeter) detector, which provides high voltages to about 104 photomultipliers (PMTs). This paper presents the new interfacing architecture for the system and details the design of a prototype control board (HVRemote-Ctrl) used for test and validation of the new architecture. The tests evaluate the system multiplexing capabilities needed to monitor all the TileCal PMTs in real time. The communication channels involved, supported in Ethernet and SPI interfaces/protocols, have been fully tested. Some results from the tests already completed are presented

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

The calibration system for the photomultiplier array of the SNO+ experiment

A light injection system using LEDs and optical fibres was designed for the calibration and monitoring of the photomultiplier array of the SNO+ experiment at SNOLAB. Large volume, non-segmented, low-background detectors for rare event physics, such as the multi-purpose SNO+ experiment, need a calibration system that allow an accurate and regular measurement of the performance parameters of their photomultiplier arrays, while minimising the risk of radioactivity ingress. The design implemented for SNO+ uses a set of optical fibres to inject light pulses from external LEDs into the detector. The design, fabrication and installation of this light injection system, as well as the first commissioning tests, are described in this paper. Monte Carlo simulations were compared with the commissioning test results, confirming that the system meets the performance requirements

Development of a detector (ALFA) to measure the absolute LHC luminosity at ATLAS

The ATLAS collaboration plans to determine the absolute luminosity of the CERN LHC at Interaction Point 1 by measuring the trajectory of protons elastically scattered at very small angles ($\mu rad$). A scintillating fibre tracker system called ALFA (Absolute Luminosity For ATLAS) is proposed for this measurement. Detector modules will be placed above and below the LHC beam axis in roman pot units at a distance of 240 m on each side of the ATLAS interaction point. They allow the detectors to approach the beam axis to millimeter distance. Overlap detectors also based on the scintillating fibre technology, will measure the precise relative position of the two detector modules. Results obtained during beam tests at DESY and at CERN validate the detectors design and demonstrate the achievable resolution. We also report about radiation hardness studies of the scintillating fibres to estimate the lifetime of the ALFA system at different operating conditions of the LHC

Operation and performance of the ATLAS Tile Calorimeter in Run 1

The Tile Calorimeter is the hadron calorimeter covering the central region of the ATLAS experiment at the Large Hadron Collider. Approximately 10,000 photomultipliers collect light from scintillating tiles acting as the active material sandwiched between slabs of steel absorber. This paper gives an overview of the calorimeter’s performance during the years 2008–2012 using cosmic-ray muon events and proton–proton collision data at centre-of-mass energies of 7 and 8TeV with a total integrated luminosity of nearly 30 fb−1. The signal reconstruction methods, calibration systems as well as the detector operation status are presented. The energy and time calibration methods performed excellently, resulting in good stability of the calorimeter response under varying conditions during the LHC Run 1. Finally, the Tile Calorimeter response to isolated muons and hadrons as well as to jets from proton–proton collisions is presented. The results demonstrate excellent performance in accord with specifications mentioned in the Technical Design Report

Upgrade of the ATLAS Tile Calorimeter high voltage system

The high voltage system of TileCal, the ATLAS central hadron calorimeter, is being upgraded for the high-luminosity LHC, in the so called phase II upgrade. In the new configuration for the upgrade, the high voltage regulation boards are not located inside the detector anymore, they are deployed far from the radiation caused by the collisions, in a room where there is permanent access for maintenance. This option requires a large number of 100 m long high voltage cables but removes the requirement of radiation hardened boards. HVremote regulation boards and the respective high voltage supplies boards have been developed and tested, as well as a crate to house the boards. Preliminary results of the HVremote boards performance are presented

The ALFA Roman Pot Detectors of ATLAS

International audienceThe ATLAS Roman Pot system is designed to determine the total proton-proton cross section as well as the luminosity at the Large Hadron Collider (LHC) by measuring elastic proton scattering at very small angles. The system is made of four Roman Pot stations, located in the LHC tunnel in a distance of about 240 m at both sides of the ATLAS interaction point. Each station is equipped with tracking detectors, inserted in Roman Pots which approach the LHC beams vertically. The tracking detectors consist of multi-layer scintillating fibre structures read out by Multi-Anode-Photo-Multipliers