arXiv subjects

C. Foudas

Publications and source records attributed to C. Foudas.

5 recordsLinked to original sources

arXiv2015

Run 2 Upgrades to the CMS Level-1 Calorimeter Trigger

The CMS Level-1 calorimeter trigger is being upgraded in two stages to maintain performance as the LHC increases pile-up and instantaneous luminosity in its second run. In the first stage, improved algorithms including event-by-event pile-up corrections are used. New algorithms for heavy ion running have also been developed. In the second stage, higher granularity inputs and a time-multiplexed approach allow for improved position and energy resolution. Data processing in both stages of the upgrade is performed with new, Xilinx Virtex-7 based AMC cards.

physics.ins-det↗

arXiv2008

The CMS Level-1 Trigger at LHC and Super-LHC

The Level-1 trigger of the CMS experiment at CERN has been designed to select proton-proton interactions whose final state includes signatures of new physics in the form of high transverse energy electrons, photons, jets, or high missing transverse energy. The Level-1 trigger system process data in a pipeline fashion at a rate of 40 MHz, has a design latency of 128 bunch crossings and an output rate of 100 KHz. The design of this system is presented with emphasis on the calorimeter triggers. After a long period of testing and validation of its performance the Level-1 trigger system has been installed and commissioned at the CMS experiment at CERN. Cosmic ray data and Monte Carlo events have been used to compare the actual performance of the trigger with expectations from off-line emulation models. Results from these studies are presented here. The limitations of this system to cope with future luminosity upgrades of the LHC, the Super-LHC, are discussed. The current CMS plan for a new CMS Level-1 trigger system at the Super-LHC is presented. The center point of the new system is a Level-1 tracking trigger which uses data from a new CMS silicon tracking detector.

physics.ins-det↗

arXiv2005

A Study for a Tracking Trigger at First Level for CMS at SLHC

It is expected that the LHC accelerator and experiments will undergo a luminosity upgrade which will commence after several years of running. This part of the LHC operations is referred to as Super-LHC (SLHC) and is expected to provide beams of an order of magnitude larger luminosity (1035cm-2sec-1) than the current design. Preliminary results are presented from a feasibility study for a First Level Tracking Trigger for CMS at the SLHC using the data of the inner tracking detector. As a model for these studies the current CMS pixel detector with the same pixel size and radial distances from the beam has been used. Monte Carlo studies have been performed using the full CMS simulation package (OSCAR) and the occupancy of such a detector at SLHC beam conditions has been calculated. The design of an electron trigger which uses both the calorimeter energy depositions and the pixel data to identify isolated electrons and photons has been investigated. Results on the tracker occupancy and the electron trigger performance are presented

physics.ins-det↗

arXiv2005

A Pixel Detector for Level-1 Triggering at SLHC

We report on preliminary design studies of a pixel detector for CMS at the Super-LHC. The goal of these studies was to investigate the possibility of designing an inner tracker pixel detector whose data could be used for selecting events at the First Level Trigger. The detector considered consists of two layers of 20x50x10 um3 pixels at very close radial proximity from each other so that coincidences of hits between the two layers amount to a track transverse momentum (pT) cut. This cut reduces the large amount of low-momentum data expected at SLHC while keeping the tracking efficiency very high for the high pT tracks. Preliminary results on the performance of such a detector are presented.

physics.ins-det↗

arXiv2005

The CMS Tracker Readout Front End Driver

The Front End Driver, FED, is a 9U 400mm VME64x card designed for reading out the Compact Muon Solenoid, CMS, silicon tracker signals transmitted by the APV25 analogue pipeline Application Specific Integrated Circuits. The FED receives the signals via 96 optical fibers at a total input rate of 3.4 GB/sec. The signals are digitized and processed by applying algorithms for pedestal and common mode noise subtraction. Algorithms that search for clusters of hits are used to further reduce the input rate. Only the cluster data along with trigger information of the event are transmitted to the CMS data acquisition system using the S-LINK64 protocol at a maximum rate of 400 MB/sec. All data processing algorithms on the FED are executed in large on-board Field Programmable Gate Arrays. Results on the design, performance, testing and quality control of the FED are presented and discussed.

physics.ins-det↗