704 research outputs found
Results from prototypes of environmental and health alarm devices based on gaseous detectors operating in air in counting mode
International audienceWe have developed and successfully tested two prototypes of detectors of dangerous gases based on wire-type counters operating in air in avalanche mode: one is for radon (Rn) detection whereas the other one is for the detection of gases with an ionization potential less than the air components. Due to the operation in pulse counting mode these prototypes have sensitivities comparable to (in the case of the Rn detector) or much higher than (in the case of the detector for low ionization gases) the best commercial devices currently available on the market. We believe that due to their high sensitivity, simplicity and low cost such new detectors will find massive applications. One of them, discussed in this paper, could be the on-line monitoring of Rn for the prediction of earthquakes
Results from the ageing studies of large CsI photocathodes exposed to ionizing radiation in a gaseous RICH detector
We studied the ageing of large CsI photocathodes induced by ionizing particles (90Sr) by correlating the integrated charge dose of the ionic avalanches hitting the photocathode to the local changes of the Quantum Efficiency (QE). The drop of the QE of the irradiated CsI spots is reported as a function of the charge dose. It was found that the ageing process continues even in absence of irradiation
Production technique and quality evaluation of CsI photocathodes for the ALICE/HMPID detector
Abstract The ALICE/HMPID detector has been equipped with 42 large area CsI photocathodes providing a total of 11 m 2 of photosensitive area for the detection of Cherenkov light. This production summary reports on the CsI coating procedure and provides results of the quality monitoring measurements by means of a photocurrent scanner system. The importance of the heat enhancement of CsI PCs is stressed and difficulties due to variations in this process are presented, followed by a discussion of possible influences of production parameters on this process
Summary and Conclusions of the First DESY Test Beam User Workshop
On October 5/6, 2017, DESY hosted the first DESY Test Beam User Workshop [1]
which took place in Hamburg. Fifty participants from different user
communities, ranging from LHC (ALICE, ATLAS, CMS, LHCb) to FAIR (CBM, PANDA),
DUNE, Belle-II, future linear colliders (ILC, CLIC) and generic detector R&D
presented their experiences with the DESY II Test Beam Facility, their concrete
plans for the upcoming years and a first estimate of their needs for beam time
in the long-term future beyond 2025. A special focus was also on additional
improvements to the facility beyond its current capabilities
R&D in ALICE: The CsI-based RICH high momentum particle identification detector
We report on the R&D studies performed on a CsI-based RICH detector with a liquid perfluorohexane radiator running pure methane at atmospheric pressure. The development, initiated by the CERN RD26 project in 1993, has been pursued in the framework of the ALICE/HMPID collaboration. A prototype of the detector under construction for ALICE is taking data since two years in the STAR experiment at RHIC
Digital Pixel Test Structures implemented in a 65 nm CMOS process
The ALICE ITS3 (Inner Tracking System 3) upgrade project and the CERN EP R&D
on monolithic pixel sensors are investigating the feasibility of the Tower
Partners Semiconductor Co. 65 nm process for use in the next generation of
vertex detectors. The ITS3 aims to employ wafer-scale Monolithic Active Pixel
Sensors thinned down to 20 to 40 um and bent to form truly cylindrical half
barrels. Among the first critical steps towards the realisation of this
detector is to validate the sensor technology through extensive
characterisation both in the laboratory and with in-beam measurements. The
Digital Pixel Test Structure (DPTS) is one of the prototypes produced in the
first sensor submission in this technology and has undergone a systematic
measurement campaign whose details are presented in this article.
The results confirm the goals of detection efficiency and non-ionising and
ionising radiation hardness up to the expected levels for ALICE ITS3 and also
demonstrate operation at +20 C and a detection efficiency of 99% for a DPTS
irradiated with a dose of 1 MeV ncm.
Furthermore, spatial, timing and energy resolutions were measured at various
settings and irradiation levels.Comment: Updated threshold calibration method. Implemented colorblind friendly
color palette in all figures. Updated reference
Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV
We report the first measurement of charged particle elliptic flow in Pb-Pb
collisions at 2.76 TeV with the ALICE detector at the CERN Large Hadron
Collider. The measurement is performed in the central pseudorapidity region
(||<0.8) and transverse momentum range 0.2< < 5.0 GeV/. The
elliptic flow signal v, measured using the 4-particle correlation method,
averaged over transverse momentum and pseudorapidity is 0.087 0.002
(stat) 0.004 (syst) in the 40-50% centrality class. The differential
elliptic flow v reaches a maximum of 0.2 near = 3
GeV/. Compared to RHIC Au-Au collisions at 200 GeV, the elliptic flow
increases by about 30%. Some hydrodynamic model predictions which include
viscous corrections are in agreement with the observed increase.Comment: 10 pages, 4 captioned figures, published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/389
Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions
We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe
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