Article

First proton–proton collisions at the LHC as observed with the ALICE detector: measurement of the charged-particle pseudorapidity density at GeV

[more]
(Impact Factor: 5.08). 01/2010; 65(1):111-125.

ABSTRACT

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 450GeV 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|<0.5, we obtain dN
ch/dη=3.10±0.13(stat.)±0.22(syst.) for all inelastic interactions, and dN
ch/dη=3.51±0.15(stat.)±0.25(syst.) for non-single diffractive interactions. These results are consistent with previous measurements
in proton–antiproton interactions at the same centre-of-mass energy at the CERN Sp
[`(p)]\overline{\mathrm{p}}
S collider. They also illustrate the excellent functioning and rapid progress of the LHC accelerator, and of both the hardware
and software of the ALICE experiment, in this early start-up phase.

Full-text

Available from: Varlen Grabski
• Source
Article: Status of the LHC
[Hide abstract]
ABSTRACT: The Large Hadron Collider (LHC) will provide particle physics with a tool to access the energy frontier above 1 TeV. To deliver proton-proton collisions at the centre of mass energy of 14 TeV with a nominal luminosity of 1034 cm-2s-1, the LHC will operate with high-field dipole magnets using NbTi superconductors cooled below the l-point of helium. Following a decade of R&D and technical validation of major collider sub-systems, the LHC main components are being built in industry and procured through world-wide collaboration. For final validation of the entire system and preparation of machine operation, a full-scale prototype of a lattice cell is being commissioned. The machine equipment and protection systems are being prepared to operate with about 3 x 10**14 protons/beam. The energy stored in one beam is 350 MJ, more than seven orders of magnitude above the quench limit of a superconducting magnet. After briefly recalling the challenges and design choices of the machine, status and future prospects are discussed.
Preview · Article ·
• Source
Article: An Overview of the ALICE Experiment
[Hide abstract]
ABSTRACT: A Large Ion Collider Experiment (ALICE) is an experiment de- signed to probe the inner depths of matter. Specically it aims to un- derstand the hot and dense matter created during collisions of heavy lead ions in the CERN Large Hadron Collider. It is believed that just after the collision the matter will be in a state called the quark- gluon plasma(QGP) where quarks become deconned. Aside from an overview of the ALICE detector, this paper will discuss the physics of the QGP, detection methods, previous discoveries about the QGP along with the current status of ALICE.
Preview · Article ·
• Article: Use of a scintillator based on an activated paraterphenyl polycrystal as part of a phoswich detector
[Hide abstract]
ABSTRACT: The possibility of designing phoswich detectors comprising organic polycrystalline scintillators for simultaneous and separate detection of β and γ rays has been investigated. Activated n-terphenyl polycrystals of a certain thickness were produced for these detectors by molding solution-grown raw material in the shape of plates at premelting temperatures. It is shown that the spectrometric and radiometric characteristics of the phoswich detectors can be improved by using these polycrystals, as well as by gluing two scintillators by optical adhesive compositions based on high-purity polymethyl phenylsiloxane rubber.
No preview · Article · Nov 2008 · Instruments and Experimental Techniques