122908768
The Alice silicon pixel detector
CERN European Organization for Nuclear Research, CH-1211 Geneva 23, Switzerland Universita degli Studi di Padova, I-35131, Padova, Italy Dipartimento IA di Fisica e Sez. INFN di Bari, I-70126,Bari,Italy Comenius University, SK-84215 Bratislava, Slovakia NIKHEF, National Institute for Nuclear Physics and High Energy Physics, 1098 SJ Amsterdam, The Netherlands Slovak Academy of Sciences, SK-04353, Kosice, Slovakia Universita di Roma I, La Sapienza, I-00185, Roma, Italy
109039717
Test beam performance of the ALICE silicon pixel detector
Abstract The ALICE Silicon Pixel Detector (SPD) will include 1200 bump-bonded readout chips produced in a commercial 0.25 μ CMOS process. Each chip has 8192 pixels of size 50 × 425 μ m 2 , which leads to about 10 million readout channels in the whole detector system. Test beam measurements were recently carried out at the CERN SPS using a positive proton/pion beam as well as a 158 A GeV/c heavy ion beam (In) with a fixed Pb target. Analysis show good performance of the ALICE chip and assemblies in the positive beam as well as in the high multiplicity In beam. Preliminary results from data analysis show good performance of the SPD and fulfill the ALICE requirements.
121671017
Recent test results of the ALICE silicon pixel detector
The ALICE SPD (Silicon Pixel Detector) forms the two innermost layers of the Inner Tracking System (ITS) of the ALICE experiment at LHC. After several years of development the production of the modules is starting. The present article provides an overview of the different elements that will be used in the SPD with special emphasis given to testing of wafers and bump-bonded ladders.
17385077
Critical amplitudes and mass spectrum of the 2d Ising model in a magnetic field
Abstract We compute the spectrum and several critical amplitudes of the two-dimensional Ising model in a magnetic field with the transfer matrix method. The three lightest masses and their overlaps with the spin and the energy operators are computed on lattices of a width up to L 1 =21 . In extracting the continuum results we also take into account the corrections to scaling due to irrelevant operators. In contrast with previous Monte Carlo simulations our final results are in perfect agreement with the predictions of S-matrix and conformal field theory. We also obtain the amplitudes of some of the subleading corrections, for which no S-matrix prediction has yet been obtained.
10634649
The Kazakov-Migdal model as a high temperature lattice gauge theory
Abstract We show that the Kazakov-Migdal (KM) induced gauge model d dimensions describes the high temperature limit of ordinary lattice gauge theories in d +1 dimensions. The matter fields are related to the Polyakov loops, while the spatial gauge variables become the gauge fields of the KM model. This interpretation of the KM model is in agreement with some recent results in high temperature lattice QCD.
119225332
A new approach to the study of effective string corrections in LGTs
We propose a new approach to the study of the interquark potential in Lattice Gauge Theories. Instead of looking at the expectation value of Polyakov loop correlators we study the modifications induced in the chromoelectric flux by the presence of the Polyakov loops. In abelian LGTs, thanks to duality, this study can be performed in a very efficient way, allowing to reach high precision at a reasonable CPU cost. The major advantage of this strategy is that it allows us to eliminate the dominant effective string correction to the interquark potential (the Lüscher term) thus giving an unique opportunity to test higher order corrections. Performing a set of simulations in the 3d spin Ising model and then translating the result in the 3d gauge Ising model using duality, we were thus able to precisely identify and measure both the quartic and the sextic effective string corrections to the interquark potential. While the quartic term perfectly agrees with the Nambu–Goto one the sextic term is definitely different. Our result seems to disagree with the recent proof of the universality of the sextic correction. We discuss a few possible explanations of this disagreement.
18539443
EFFECTIVE STRING PICTURE FOR CONFINING GAUGE THEORIES AT FINITE TEMPERATURE
We study the ``effective string picture'' of confinement, deriving theoretical predictions for the interquark potential at finite temperature. At low temperatures, the leading string correction to the linear confining potential between a heavy quark-antiquark pair is the "L\"uscher term''. Assuming a Nambu-Goto effective string action, subleading contributions can be worked out in an analytical way. We also discuss the contribution given by a possible ``boundary term'' in the effective action, and compare these predictions with high precision results from simulations of lattice Z(2) gauge theory in three dimensions, obtained with an algorithm that exploits the duality of the Z(2) gauge model with the Ising spin model.