2,992 research outputs found
New building blocks for the ALICE SDD readout and Detector Control System in a commercial 0.25 m CMOS technology
Beam test results of the irradiated Silicon Drift Detector for ALICE
The Silicon Drift Detectors will equip two of the six cylindrical layers of
high precision position sensitive detectors in the ITS of the ALICE experiment
at LHC. In this paper we report the beam test results of a SDD irradiated with
1 GeV electrons. The aim of this test was to verify the radiation tolerance of
the device under an electron fluence equivalent to twice particle fluence
expected during 10 years of ALICE operation.Comment: 6 pages,6 figures, to appear in the proceedings of International
Workshop In high Multiplicity Environments (TIME'05), 3-7 October 2005,
Zurich,Switzerlan
The Straw Tube Trackers of the PANDA Experiment
The PANDA experiment will be built at the FAIR facility at Darmstadt
(Germany) to perform accurate tests of the strong interaction through bar pp
and bar pA annihilation's studies. To track charged particles, two systems
consisting of a set of planar, closed-packed, self-supporting straw tube layers
are under construction. The PANDA straw tubes will have also unique
characteristics in term of material budget and performance. They consist of
very thin mylar-aluminized cathodes which are made self-supporting by means of
the operation gas-mixture over-pressure. This solution allows to reduce at
maximum the weight of the mechanical support frame and hence the detector
material budget. The PANDA straw tube central tracker will not only reconstruct
charged particle trajectories, but also will help in low momentum (< 1 GeV)
particle identification via dE/dx measurements. This is a quite new approach
that PANDA tracking group has first tested with detailed Monte Carlo
simulations, and then with experimental tests of detector prototypes. This
paper addresses the design issues of the PANDA straw tube trackers and the
performance obtained in prototype tests.Comment: 7 pages,16 figure
Effect of Finite Granularity of Detectors on Anisotropy Coefficients
The coefficients that describe the anisotropy in the azimuthal distribution
of particles are lower when the particles are recorded in a detector with
finite granularity and measures only hits. This arises due to loss of
information because of multiple hits in any channel. The magnitude of this loss
of signal depends both on the occupancy and on the value of the coefficient.
These correction factors are obtained for analysis methods differing in detail,
and are found to be different.Comment: 11 pages including 2 figure
Measurement of shower development and its Moli\`ere radius with a four-plane LumiCal test set-up
A prototype of a luminometer, designed for a future e+e- collider detector,
and consisting at present of a four-plane module, was tested in the CERN PS
accelerator T9 beam. The objective of this beam test was to demonstrate a
multi-plane tungsten/silicon operation, to study the development of the
electromagnetic shower and to compare it with MC simulations. The Moli\`ere
radius has been determined to be 24.0 +/- 0.6 (stat.) +/- 1.5 (syst.) mm using
a parametrization of the shower shape. Very good agreement was found between
data and a detailed Geant4 simulation.Comment: Paper published in Eur. Phys. J., includes 25 figures and 3 Table
A new measurement of J/psi suppression in Pb-Pb collisions at 158 GeV per nucleon
We present a new measurement of J/psi production in Pb-Pb collisions at 158
GeV/nucleon, from the data sample collected in year 2000 by the NA50
Collaboration, under improved experimental conditions with respect to previous
years. With the target system placed in vacuum, the setup was better adapted to
study, in particular, the most peripheral nuclear collisions with unprecedented
accuracy. The analysis of this data sample shows that the (J/psi)/Drell-Yan
cross-sections ratio measured in the most peripheral Pb-Pb interactions is in
good agreement with the nuclear absorption pattern extrapolated from the
studies of proton-nucleus collisions. Furthermore, this new measurement
confirms our previous observation that the (J/psi)/Drell-Yan cross-sections
ratio departs from the normal nuclear absorption pattern for semi-central Pb-Pb
collisions and that this ratio persistently decreases up to the most central
collisions.Comment: 19 pages, 10 figures. Submitted to Eur. Phys. J.
J/psi azimuthal anisotropy relative to the reaction plane in Pb-Pb collisions at 158 GeV per nucleon
The J/ azimuthal distribution relative to the reaction plane has been
measured by the NA50 experiment in Pb-Pb collisions at 158 GeV/nucleon. Various
physical mechanisms related to charmonium dissociation in the medium created in
the heavy ion collision are expected to introduce an anisotropy in the
azimuthal distribution of the observed J/ mesons at SPS energies. Hence,
the measurement of J/ elliptic anisotropy, quantified by the Fourier
coefficient v of the J/ azimuthal distribution relative to the
reaction plane, is an important tool to constrain theoretical models aimed at
explaining the anomalous J/ suppression observed in Pb-Pb collisions. We
present the measured J/ yields in different bins of azimuthal angle
relative to the reaction plane, as well as the resulting values of the Fourier
coefficient v as a function of the collision centrality and of the
J/ transverse momentum. The reaction plane has been estimated from the
azimuthal distribution of the neutral transverse energy detected in an
electromagnetic calorimeter. The analysis has been performed on a data sample
of about 100 000 events, distributed in five centrality or p
sub-samples. The extracted v values are significantly larger than zero
for non-central collisions and are seen to increase with p.Comment: proceedings of HP08 conference corrected a typo in one equatio
Performance of fully instrumented detector planes of the forward calorimeter of a Linear Collider detector
Detector-plane prototypes of the very forward calorimetry of a future
detector at an e+e- collider have been built and their performance was measured
in an electron beam. The detector plane comprises silicon or GaAs pad sensors,
dedicated front-end and ADC ASICs, and an FPGA for data concentration.
Measurements of the signal-to-noise ratio and the response as a function of the
position of the sensor are presented. A deconvolution method is successfully
applied, and a comparison of the measured shower shape as a function of the
absorber depth with a Monte-Carlo simulation is given.Comment: 25 pages, 32 figures, revised version following comments from
referee
Radiation damage of silicon strip detectors in the NA50 experiment
Abstract During operation of the multiplicity detector in the NA50 experiment the single sided AC-coupled p-on-n silicon strip detectors were exposed to charged particle fluences up to 10 14 eq n/cm 2 and ionising doses up to 20 Mrad, with a very non-uniform radiation spatial distribution. Radiation effects in the detectors observed during the '96 lead ion run as well as results of the post-run measurements are presented in this paper
The dependence of the anomalous J/psi suppression on the number of participant nucleons
The observation of an anomalous J/psi suppression in Pb-Pb collisions by the NA50 Collaboration can be considered as the most striking indication for the deconfinement of quarks and gluons at SPS energies. In this Letter, we determine the J/psi suppression pattern as a function of the forward hadronic energy E-ZDC measured in a Zero Degree Calorimeter (ZDC). The direct connection between EZDC and the geometry of the collision allows us to calculate, within a Glauber approach, the precise relation between the number of participant nucleons N-part and E-ZDC. Then, we check if the experimental data can be better explained by a sudden or a smooth onset of the anomalous J/psi suppression as a function of the number of participants. (C) 2001 Elsevier Science B.V. All rights reserved.info:eu-repo/semantics/publishedVersio
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