Pulsed beam measurement system

This article describes the elements of the pulsed beam measurement system at the AMS facility in Utrecht, in particular the switched power supplies and the current integrator

Assembly and validation of the SSD silicon microstrip detector of ALICE

The Silicon Strip Detector (SSD) forms the two outermost layers of the Inner Tracking System (ITS) of ALICE. The SSD detector consists of 1698 double-sided silicon microstrip modules. The electrical connection between silicon sensor and front-end electronics is made via TAB-bonded aluminium–polyimide cables (chip-cables). The module assembly is challenging because of the module geometry and the use of chip-cables. This article describes the assembly procedure and the test protocol used

The ALICE vertex detector: focus on the micro-strip layers

The ALICE experiment, which is being installed at the Large Hadron Collider at CERN, is designed to operate in a high-track density environment which is typical of relativistic heavy ions physics. This paper reports the main characteristics of the Inner Tracking System (ITS) of ALICE and describes the Silicon Strip Detector, which forms the two outermost layers of the ITS

Front-end modules for ALICE SSD

The Silicon Strip Detector (SSD) front-end module will populate the two outer layers of the ALICE inner tracker. After years of design and developments reported in the previous proceedings of the LECC workshop [1], [2], [3], several working prototypes of this module have been produced with the final components in two different laboratories. The first test results will be presented

In-beam performance of the ALICE silicon strip detectors

This paper presents the beam test results of the first four double-sided silicon strip modules built for the inner tracker of ALICE detector. The basic detector performance was studied with the focus made on the efficiency and spatial resolution determination. A fast method for the determination of the spatial resolution of the sensors in the telescope is described

The ALICE experiment at the CERN LHC

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 m3 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

ALICE electromagnetic calorimeter technical design report

ALICE (A Large Ion Collider Experiment) at the LHC contains a wide array of detector systems for measuring hadrons, leptons, and photons. ALICE is designed to carry out comprehensive measurements of high energy nucleus-nucleus collisions, in order to study QCD matter under extreme conditions and to study the phase transition between confined matter and the Quark-Gluon Plasma (QGP). Discussion of the full ALICE physics program can be found in [1, 2]. The interaction and energy loss of high energy partons in matter provides a sensitive tomographic probe of the medium generated in high energy nuclear collisions (“jet quenching”) [3–6]. Jet quenching measurements have played a key role at the Relativistic Heavy Ion Collider (RHIC) [7–10] and will be central to the study of nuclear collisions at the LHC. This Technical Design Report describes a large acceptance Electromagnetic Calorimeter (EMCal) that will be installed in the ALICE central detector. The EMCal enhances ALICE's capabilities for jet quenching measurements. The addition of the EMCal enables triggering on high energy jets, reduces significantly the measurement bias for jet quenching studies, improves jet energy resolution, and augments existing ALICE capabilities to measure high momentum photons and electrons. Combined with ALICE's excellent capabilities to track and identify particles from very low pt to high pt the EMCal enables an extensive study of jet quenching at the LHC

First proton–proton collisions at the LHC as observed with the ALICE detector: measurement of the charged-particle pseudorapidity density at [v]s=900 GeV

On 23rd November 2009, during the early commissioning of the CERN Large Hadron Collider (LHC), two counter-rotating proton bunches were circulated for the first time concurrently in the machine, at the LHC injection energy of 450 GeV per beam. Although the proton intensity was very low, with only one pilot bunch per beam, and no systematic attempt was made to optimize the collision optics, all LHC experiments reported a number of collision candidates. In the ALICE experiment, the collision region was centred very well in both the longitudinal and transverse directions and 284 events were recorded in coincidence with the two passing proton bunches. The events were immediately reconstructed and analyzed both online and offline. We have used these events to measure the pseudorapidity density of charged primary particles in the central region. In the range |η