121781476
First performance studies of a pixel-based trigger in the CMS experiment
An important tool for the discovery of new physics at LHC is the design of a low level trigger with an high power of background rejection. The contribution of pixel detector to the lowest level trigger at CMS is studied focusing on low-energy jet identification, matching the information from calorimeters and pixel detector. In addition, primary vertex algorithms are investigated. The performances are evaluated in terms of, respectively, QCD rejection and multihadronic jets final states efficiency.
2971912
The CMS tracker Data Quality Monitoring expert GUI
Data Quality Monitoring (DQM) is mandatory in a high energy physics experiment like the Compact Muon Solenoid (CMS) at the CERN Large Hadron Collider (LHC). For the CMS Silicon Strip Tracker, the largest detector of this kind ever built, the DQM tasks translate into monitoring of 15148 silicon detector modules for a total of 9.3 million channels. An expert level Graphical User Interface has been developed to manage this highly granular information where the statistical characteristics of more than 350000 histograms are analyzed online during data-taking in order to raise warnings or alarms. In addition, specific quantities can be recalled on demand for problems investigation or online feedback on the data quality.
123498730
CMS tracker performance
Abstract The Compact Muon Solenoid (CMS) experiment is a multipurpose high energy physics detector operated at the CERN Large Hadron Collider (LHC) near Geneva, Switzerland. The current status and performance of the CMS silicon tracker after 2 years of p–p collisions at s = 7 TeV are reviewed.
119968739
CMS Silicon Strip Tracker Commissioning and Preliminary Performances
The Silicon Strip Tracker (SST) of the Compact Muon Solenoid (CMS) Experiment at the CERN Large Hadron Collider (LHC) is the world's largest silicon microstrip detector. The SST is composed of four subdetectors which were integrated into the Tracker Support Tube (TST) at the CERN Tracker Integration Facility (TIF) in March 2007. After the insertion of the TST into CMS in December 2007, the first data taking of CMS with the SST included took place in July 2008 without magnetic field and one month later with a magnetic field of 3.8 Tesla. The SST was ready for the LHC start-up of September 10, 2008. The main aspects of the SST commissioning and a description of the problems encountered and solved so far are summarized here together with some preliminary performance evaluation.
102340714
CMS Tracker, ECAL and Pixel Optical Cabling: Installation and Performance Verification
The installation of 52304 optical links for the readout and control of the CMS Tracker, ECAL and Pixel detectors is complete. 768 96-way optical cables were installed and tested using an optical time-domain reflectometer. The testing was followed by connections at high density optical fibre patchpanels. Finally, a further round of testing and troubleshooting following feedback from system commissioning with the Tracker Data Acquisition was carried out. Over 90% of the faults found were recovered, resulting overall in only 0.1% of dead optical link channels in the CMS Tracker.
110850685
First level trigger using pixel detector for the CMS experiment
A proposal for a pixel-based Level 1 trigger for the Super-LHC is presented. The trigger is based on fast track reconstruction using the full pixel granularity exploiting a readout which connects different layers in specific trigger towers. The trigger will implement the current CMS high level trigger functionality in a novel concept of intelligent detector. A possible layout is discussed and implications on data links are evaluated.
123495225
A large-area time-of-flight system for a colliding beam machine
Abstract We describe the performance of a large solid-angle (2 sr) time-of-flight system used in conjunction with the Split Field Magnet spectrometer of the CERN Intersecting Storage Rings (ISR). The system consists of a hodoscope of 67 scintillator counters, at a distance of about 5 m from the beam intersection. The ISR being a coasting beam machine, contrary to the tightly bunched e + e − machines, the event time is unknown and therefore a special analysis procedure for particle identification is required. We illustrate a powerful statistical method which allows the identification, with more than 90% efficiency, of pions up to about 1 GeV/c, kaons up to about 1.4 GeV/c, and protons up to about 2 GeV/c.
209911742
Proof of hadron production in (e+e−) interactions.
117276470
New ISR physics: Heavy flavors and multihadronic final states
120972616
A limited-streamer tube electron detector with high rejection power against pions
Abstract The problem of detecting electrons in the 0.5–4.0 GeV energy range, in the presence of a high pion background, has been studied using a new type of electromagnetic shower detector. Its structural properties and the main parameters are given, together with the basic results in terms of energy resolution and of rejection power against pion background. The optimization of this new instrument gives a pion rejection power of ∼ 6 × 10 −4 for energy ≳ 1.2 GeV.
120197754
Primary Ionization Measurement in a Large Avalanche Chamber for Free Quark Detection
The WA44 experiment is a search for free quarks (1/3, 1/2) produced in high energy v interactions. High detection efficiency for quarks is achieved by measurement of primary ionization in a triggered large avalanche chamber which, moreover, provides the high spatial resolution required for high multiplicity jet-type events. The chamber is 2.35 × 1.25 × 0.6 m3 and is flushed with a mixture of pure He-Ne (80-20%). The chamber is photographed with 3 cameras using image intensifiers giving 1.4 mm resolution in space. The optical gain is such that the chamber can be operated well below the streamer threshold. In order to obtain precise primary ionization measurements and high rejection coefficient for quark detection against charge 1 particles, a good high voltage pulse stability (< 1% FWHM) and a long memory time (at least 100 μs) are essential and have been achieved. Data taking is in progress. Preliminary results show that the avalanche chamber is an excellent triggerable detector for combining good spatial multitrack resolution and accurate primary ionization measurement.