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 161626 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.

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The ALICE experiment at the CERN LHC

A new method for the measurement of the time dependence of the light intensity from scintillators is described. An important aspect of the method is the ease with which it can be applied to all modes of excitation. The results of measurements on the time dependence of the scintillators for several modes of excitation are presented.

Measurement of the Time Dependence of Scintillation Intensity by a Delayed‐Coincidence Method

ALICE is a general-purpose heavy-ion detector designed to study the physics of strongly interacting matter and the quark-gluon plasma in nucleus-nucleus collisions at the LHC at a center of mass energy of 5.5 TeV/nucleon. It is currently under construction and will be ready for data taking at LHC turn-on in 2007. The collaboration currently includes more than 900 physicists, both from nuclear physics and high-energy physics, from over 70 institutions in 27 countries.

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The alice experiment at the CERN LHC

Clinical trials using accelerated heavy charged‐particle beams for treating cancer and other diseases have been performed for nearly four decades. Recently there have been worldwide efforts to construct hospital‐based medically dedicated proton or light‐ion accelerator facilities. To make such accelerated heavy charged‐particle beams clinically useful, specialized instruments must be developed to modify the physical characteristics of the particle beams in order to optimize their biological and clinical effects. This article reviews the beam modifying devices and associated dosimetric equipment developed specifically for controlling and monitoring the clinical beams.

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Instrumentation for Treatment of Cancer Using Proton and Light-Ion Beams

A possibility of manufacturing plastic scintillators with efficient neutron/gamma pulse shape discrimination (PSD) is demonstrated using a system of a polyvinyltoluene (PVT) polymer matrix loaded with a scintillating dye, 2,5-diphenyloxazole (PPO). Similarities and differences of conditions leading to the rise of PSD in liquid and solid organic scintillators are discussed based on the classical model of excited state interaction and delayed light formation. First characterization results are presented to show that PSD in plastic scintillators can be of the similar magnitude or even higher than in standard commercial liquid scintillators.

Plastic scintillators with efficient neutron/gamma pulse shape discrimination

A scintillation counter with neutron and gamma-ray discriminators

Development of organic scintillators

Methods of neutron field spectrometry, other than those depending on the use of pulsed neutron sources, are surveyed. Neutron spectrometers are compared with particular reference to characteristics such as energy resolution, useful energy range, neutron detection efficiency and response functions.

Neutron spectrometry-historical review and present status

Quasi-monoenergetic reference neutron beams in the energy range between 20 and 100 MeV have been produced and characterized with a proton recoil telescope, a scintillation spectrometer, a U-238 fission chamber and a Bonner sphere spectrometer. The beams are well suited for the calibration of detectors used in neutron spectrometry. A new method is described which reduces the correction for the contribution from low-energy neutrons present in the beams. (C) 2002 Elsevier Science B.V. All rights reserved.

High-energy neutron reference fields for the calibration of detectors used in neutron spectrometry

Well-characterised neutron fields are a prerequisite for the investigation of neutron detectors. Partly in collaboration with external partners, the PTB neutron metrology group makes available for other users neutron reference fields covering the full energy range from thermal to 200 MeV. The specification of the neutron fluence in these beams is traceable to primary standard cross sections.

F.D. Brooks

Papers

A scintillation counter with neutron and gamma-ray discriminators

Development of organic scintillators

Neutron spectrometry-historical review and present status

High-energy neutron reference fields for the calibration of detectors used in neutron spectrometry

Quasi-monoenergetic neutron reference fields in the energy range from thermal to 200 MeV.