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

Aamodt, K. ; Abel, N. ; Abeysekara, U. ; Abrahantes Quintana, A. ; Acero, A. ; Adamov, D. ; Aggarwal, M. M. ; Aglieri Rinella, G. ; Agocs, A. G. ; Sinha, B. C. ; et., al (2010) First proton-proton collisions at the LHC as observed with the ALICE detector: measurement of the charged-particle pseudorapidity density at √s=900 GeV The European Physical Journal C - Particles and Fields, 65 (1-2). pp. 111-125. ISSN 1434-6044

Full text not available from this repository.

Official URL: http://www.springerlink.com/content/l7l7286758x3v1...

Related URL: http://dx.doi.org/10.1140/epjc/s10052-009-1227-4

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 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| < 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 p̅ 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.

Item Type:Article
Source:Copyright of this article belongs to Springer.
ID Code:70361
Deposited On:21 Nov 2011 09:01
Last Modified:21 Nov 2011 09:01

Repository Staff Only: item control page