This article presents the basic idea of VHMPID, an upgrade detector for the ALICE experiment at LHC, CERN. The main goal of this detector is to extend the particle identification capabilities of ...ALICE to give more insight into the evolution of the hot and dense matter created in Pb-Pb collisions. Starting from the physics motivations and working principles the challenges and current status of development is detailed.
We have built a RICH detector prototype consisting of a liquid C6F14 radiator and six triple Thick Gaseous Electron Multipliers (TGEMs), each of them having an active area of 10×10cm2. One triple ...TGEM has been placed behind the liquid radiator in order to detect the beam particles, whereas the other five have been positioned around the central one at a distance to collect the Cherenkov photons. The upstream electrode of each of the TGEM stacks has been coated with a 0.4μm thick CsI layer.
In this paper, we will present the results from a series of laboratory tests performed with this prototype carried out using UV light, 6keV photons from 55Fe and electrons from 90Sr as well as recent results of tests with a beam of charged pions where for the first time Cherenkov Ring images have been successfully recorded with TGEM photodetectors. The achieved results prove the feasibility of building Cherenkov detector based on CsI coated TGEMs.
R&D results on a CsI-coated triple thick GEM-based photodetector Martinengo, P.; Peskov, V.; Breskin, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2011, Volume:
639, Issue:
1
Journal Article
Peer reviewed
The very high momentum particle identification detector proposed for the ALICE upgrade is a focusing RICH using a C
4F
10 gaseous radiator. For the detection of Cherenkov photons, one of the options ...currently under investigation is to use a CsI-coated triple thick GEM with metallic or resistive electrodes. We will present results from the laboratory studies as well as preliminary results of beam tests of a RICH detector prototype consisting of a CaF
2 radiator coupled to a 10×10
cm
2 CsI-coated triple thick GEM equipped with a pad readout and GASSIPLEX-based front-end electronics. With such a prototype the detection of Cherenkov photons simultaneously with minimum ionizing particles has been achieved for the first time in a stable operation mode.
We report on the final tests performed on a CsI-based RICH detector equipped with 2
C
6F
14 radiator trays and 4 photocathodes, each of 64×38
cm
2 area. The overall performance of the detector is ...described, using different gas mixtures, in view of optimizing the photoelectron yield and the pad occupancy. Test results under magnetic field up to 0.9
T, photocathode homogeneity and stability are presented.
Two-particle correlations of negative pions as a function of charged particle multiplicity are studied in Pb+Pb collisions at \(\sqrt{s}=17.3\)GeV per nucleon using the NA44 experiment at the CERN ...Super Proton Synchrotron(SPS). We find that the source size parameters increase with the charged particle multiplicity. However the slope of the source size parameters plotted as a function of charged multiplicity is slightly larger at high multiplicity than at low multiplicity. The value of \(\lambda\) is independent of charged multiplicity. For Pb+Pb collisions, \(R_L\) is larger than \(R_{TS}\) and \(R_{TO}\) for all multiplicity intervals, whereas these three radius parameters were approximately equal in S+Nucleus collisions. The ratios (\(R_L/R_{TS}\)) and (\(R_L/R_{TO}\)) for Pb+Pb data show almost no dependence on charged multiplicity. The duration of pion emission \(\Delta \tau\) is constant at 3.8\(\pm\)1.1 fm/c as a function of the charged multiplicity in Pb+Pb collisions. Effective volume (V) is also calculated as V=\(\pi\times R_{TS}^2\times R_L\), assuming a cylindrically shaped source. We found, within the limited statistics, the effective volume rapidly increases at high multiplicity.
Performance of large area CsI-RICH prototypes for ALICE at LHC Mauro, A.Di; Cozza, D.; Davenport, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/1999, Volume:
433, Issue:
1-2
Journal Article
Front end electronics and first results of the ALICE V0 detector Zoccarato, Y.; Tromeur, W.; Aguilar, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2011, Volume:
626
Journal Article
Peer reviewed
This paper gives a detailed description of the acquisition and trigger electronics especially designed for the V0 detector of ALICE at LHC. A short presentation of the detector itself is given before ...the description of the Front End Electronics (FEE) system, which is completely embedded within the LHC environment as far as acquisition (DAQ), trigger (CTP), and detector control (DCS) are concerned. It is able to detect on-line coincident events and to achieve charge (with a precision of 0.6 pC) and time measurements (with a precision of 100
ps). It deploys quite a simple architecture. It is however totally programmable and fully non-standard in discriminating events coming from Beam–Beam interaction and Beam-Gas background. Finally, raw data collected from the first LHC colliding beams illustrate the performance of the system.
The VHMPID RICH upgrade project for ALICE at LHC Di Mauro, A.; Agocs, A.; Alfaro, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2011, Volume:
639, Issue:
1
Journal Article
Peer reviewed
RHIC results have shown the importance of high momentum particles as hard probes and the need for particle identification (PID) in a very large momentum range. A Very High Momentum PID (VHMPID) ...detector has been proposed as upgrade of ALICE to extend the track-by-track identification capabilities for charged hadrons from the present 5
GeV/c limit to the momentum range 10–30
GeV/c. The VHMPID detector is a focusing RICH using C
4F
10 gaseous radiator coupled to a CsI-based photon detector. Detector design studies, achievable Cherenkov angle resolution, expected performance and high momentum triggering will be discussed.
Parton energy loss effects in heavy-ion collisions are studied with the Monte Carlo program PQM (Parton Quenching Model) constructed using the BDMPS quenching weights and a realistic collision ...geometry. The merit of the approach is that it contains only one free parameter that is tuned to the high-pt nuclear modification factor measured in central Au-Au collisions at \(\sqrt{s_{\rm NN}} = 200\) GeV. Once tuned, the model is consistently applied to all the high-pt observables at 200 GeV: the centrality evolution of the nuclear modification factor, the suppression of the away-side jet-like correlations, and the azimuthal anisotropies for these observables. Predictions for the leading-particle suppression at nucleon-nucleon centre-of-mass energies of 62.4 and 5500 GeV are presented. The limits of the eikonal approximation in the BDMPS approach, when applied to finite-energy partons, are discussed.
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