In the last 30 days

• Open/close Alignment of the ALICE Inner Tracking System with cosmic-ray tracks

  ALICE collaboration  2010 JINST 5 P03003 Tag this article

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  ALICE (A Large Ion Collider Experiment) is the LHC (Large Hadron Collider) experiment devoted to investigating the strongly interacting matter created in nucleus-nucleus collisions at the LHC energies. The ALICE ITS, Inner Tracking System, consists of six cylindrical layers of silicon detectors with three different technologies; in the outward direction: two layers of pixel detectors, two layers each of drift, and strip detectors. The number of parameters to be determined in the spatial alignment of the 2198 sensor modules of the ITS is about 13,000. The target alignment precision is well below 10 μm in some cases (pixels). The sources of alignment information include survey measurements, and the reconstructed tracks from cosmic rays and from proton-proton collisions. The main track-based alignment method uses the Millepede global approach. An iterative local method was developed and used as well. We present the results obtained for the ITS alignment using about 10 ⁵ charged tracks from cosmic rays that have been collected during summer 2008, with the ALICE solenoidal magnet switched off.
• Open/close The ATLAS Experiment at the CERN Large Hadron Collider

  The ATLAS Collaboration and G Aad et al  2008 JINST 3 S08003 Tag this article

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  The ATLAS detector as installed in its experimental cavern at point 1 at CERN is described in this paper. A brief overview of the expected performance of the detector when the Large Hadron Collider begins operation is also presented.
• Open/close The CMS experiment at the CERN LHC

  The CMS Collaboration and S Chatrchyan et al  2008 JINST 3 S08004 Tag this article

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  The Compact Muon Solenoid (CMS) detector is described. The detector operates at the Large Hadron Collider (LHC) at CERN. It was conceived to study proton-proton (and lead-lead) collisions at a centre-of-mass energy of 14 TeV (5.5 TeV nucleon-nucleon) and at luminosities up to 10 ³⁴ cm ⁻² s ⁻¹ (10 ²⁷ cm ⁻² s ⁻¹). At the core of the CMS detector sits a high-magnetic-field and large-bore superconducting solenoid surrounding an all-silicon pixel and strip tracker, a lead-tungstate scintillating-crystals electromagnetic calorimeter, and a brass-scintillator sampling hadron calorimeter. The iron yoke of the flux-return is instrumented with four stations of muon detectors covering most of the 4π solid angle. Forward sampling calorimeters extend the pseudorapidity coverage to high values (|η| ≤ 5) assuring very good hermeticity. The overall dimensions of the CMS detector are a length of 21.6 m, a diameter of 14.6 m and a total weight of 12500 t.
• Open/close The ALICE experiment at the CERN LHC

  The ALICE Collaboration and K Aamodt et al  2008 JINST 3 S08002 Tag this article

  Article References Full text PDF (22.38 MB)

  ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries. Its overall dimensions are 16 × 16 × 26 m ³ with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008.
• Open/close A PLL based automated magnetron tuning mechanism for electron accelerators

  A M Khan et al  2008 JINST 3 P09005 Tag this article

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  In this paper we report on a control system developed to tune the magnetron frequency to get the maximum beam pulse in a Microtron (an electron accelerator facility at Mangalore University). The control system so designed consists of a Microcontroller Unit (MCU), a Phase Locked Loop (PLL) and a Digital to Analog Converter (DAC) to track and tune the magnetron frequency. A PLL is used to track the deviation of the magnetron output frequency, and by monitoring the reflected wave voltage level, the microcontroller unit tunes the magnetron with the help of a tuner mechanism connected through a stepper motor.
• Open/close The LHCb Detector at the LHC

  The LHCb Collaboration and A Augusto Alves Jr et al  2008 JINST 3 S08005 Tag this article

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  The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva). The initial configuration and expected performance of the detector and associated systems, as established by test beam measurements and simulation studies, is described.
• Open/close LHC Machine

  Lyndon Evans and Philip Bryant (editors)  2008 JINST 3 S08001 Tag this article

  Article References Full text PDF (7.36 MB)

  The Large Hadron Collider (LHC) at CERN near Geneva is the world's newest and most powerful tool for Particle Physics research. It is designed to collide proton beams with a centre-of-mass energy of 14 TeV and an unprecedented luminosity of 10 ³⁴ cm ⁻² s ⁻¹. It can also collide heavy (Pb) ions with an energy of 2.8 TeV per nucleon and a peak luminosity of 10 ²⁷ cm ⁻² s ⁻¹. In this paper, the machine design is described.
• Open/close Study of a micromegas chamber in a neutron beam

  T Alexopoulos et al  2010 JINST 5 P02005 Tag this article

  Article References Full text PDF (2.72 MB)

  The micromegas detectors are proposed as one of the options to upgrade the ATLAS muon spectrometer in the very forward/backward region. One of the problems of all detectors in the LHC and especially the ones near the beam pipe is the high neutron background. A study of a tracking micromegas detector with high flux neutrons, focusing on the sparking properties, is performed for the first time. The neutrons are supplied by the Tandem accelerator, at the N.C.S.R. ``Demokritos'' in Athens, which can provide quasi monochromatic neutrons with energies up to 25.7 MeV. The first results of this study are presented.
• Open/close Advances in solid state photon detectors

  D Renker and E Lorenz  2009 JINST 4 P04004 Tag this article

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  Semiconductor photodiodes were developed in the early `Forties approximately at the time when the photomultiplier tube became a commercial product (RCA 1939). Only in recent years, with the invention of the Geiger-mode avalanche photodiodes, have the semiconductor photo detectors reached sensitivity comparable to that of photomultiplier tubes. The evolution started in the `Sixties with the p-i-n (PIN) photodiode, a very successful device, which is still used in many detectors for high energy physics and a large number of other applications like radiation detection and medical imaging. The next step was the development of the avalanche photodiode (APD) leading to a substantial reduction of noise but not yet achieving single photon response. The weakest light flashes that can be detected by the PIN diode need to contain several hundreds of photons. An improvement of the sensitivity by 2 orders of magnitude was achieved by the development of the avalanche photodiode, a device with internal gain. At the end of the millennium, the semiconductor detectors evolved with the Geiger-mode avalanche photodiode into highly sensitive devices, which have an internal gain comparable to the gain of photomultiplier tubes and a response to single photons. A review of the semiconductor photo detector design and development, the properties and problems, some applications and a speculative outlook on the future evolution will be presented.
• Open/close Alignment of the Pixel and SCT Modules for the 2004 ATLAS Combined Test Beam

  A Ahmad et al  2008 JINST 3 P09004 Tag this article

  Article References Full text PDF (528 KB)

  A small set of final prototypes of the ATLAS Inner Detector silicon tracking system (Pixel Detector and SemiConductor Tracker), were used to take data during the 2004 Combined Test Beam. Data were collected from runs with beams of different flavour (electrons, pions, muons and photons) with a momentum range of 2 to 180 GeV/c. Four independent methods were used to align the silicon modules. The corrections obtained were validated using the known momenta of the beam particles and were shown to yield consistent results among the different alignment approaches. From the residual distributions, it is concluded that the precision attained in the alignment of the silicon modules is of the order of 5 μm in their most precise coordinate.