6,077 research outputs found
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.Comment: 8 pages 4 figure
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 presentedComment: Presented at LECC, Heidelberg 200
Stacked Tracking for CMS at Super-LHC
We report recent work on the design of a pixel detector for CMS at the Super-LHC. This work builds on previous studies of a tracking detector capable of providing track stubs to be used in the Level-1 Trigger (L1T). We now focus on the use of two âsuperlayersâ of tracking; each comprising a pair of pixel sensors with 50Ă50Ă50ÎŒm3 pitch (zĂÏĂr) separated by a few millimetres. Preliminary work on track reconstruction in Field Programmable Gate Arrays (FPGAs) is also presented
Trigger R&D for CMS at SLHC
CERN has made public a comprehensive plan for upgrading the LHC proton-proton accelerator to provide increased luminosity commonly referred to as Super LHC (SLHC) [1]. The plan envisages two phases of upgrades during which the LHC luminosity increases gradually to reach between 6-7Ă1034 cm-2sec-1. Over the past year, CMS has responded with a series of workshops and studies which have defined the roadmap for upgrading the experiment to cope with the SLHC environment. Increased luminosity will result in increased backgrounds and challenges for CMS and a major part of the CMS upgrade plan is a new Level-1 Trigger (L1T) system which will be able to cope with the high background environment at the SLHC. Two major CMS milestones will define the evolution of the CMS trigger upgrades: The change of the Hadronic Calorimeter electronics during phase-I and the introduction of the track trigger during phase-II. This paper outlines alternative designs for a new trigger system and the consequences for cost, latency, complexity and flexibility. In particular, it looks at how the trigger geometry of CMS could be mapped onto the latest generation of hardware while remaining backwards compatible with current infrastructure. A separate paper presented at this conference [2] looks at what could be possible if large parts of the trigger system were changed, or additional hardware added to create a time multiplexed trigger system
The GCT Matrix Card and its Applications
The Matrix card is the first in what is expected to be a series of xTCA cards produced for a variety of projects at CMS. It was developed as a joint collaboration between colleagues at Princeton, Imperial College, LANL and CERN. The device comprises the latest generation of readilyavailable Xilinx FPGAs, cross-point switch technology and high-density optical links in a 3U form factor. In this paper we will discuss the development and test results of the Matrix card, followed by some of the tasks to which it is being applied
The CMS Global Calorimeter Trigger Hardware Design
An alternative design for the CMS Global Calorimeter Trigger (GCT) is being implemented. The new design adheres to all the CMS specifications regarding interfaces and functional requirements of the trigger systems. The design is modular, compact, and utilizes proven components. Functionality has been partitioned to allow commissioning in stages corresponding to the different capabilities being made operational. The functional breakdown and hardware platform is presented and discussed. A related paper discusses the firmware required to implement the GCT functionality
Meson Structure Functions in Valon Model
Parton distributions in a {\it{valon}} in the next-to-leading order is used
to determine the patron distributions in pion and kaon. The validity of the
valon model is tested and shown that the partonic content of the valon is
universal and independent of the valon type. We have evaluated the valon
distribution in pion and kaon, and in particular it is shown that the results
are in good agreement with the experimental data on pion structure in a wide
range of Comment: 13 pages with 7 figures included, The manuscript is revised, figures
are added and some errors are corrected. Accepted for publication in Physical
Review
Experimental Evidence for Simple Relations between Unpolarized and Polarized Parton Distributions
The Pauli exclusion principle is advocated for constructing the proton and
neutron deep inelastic structure functions in terms of Fermi-Dirac
distributions that we parametrize with very few parameters. It allows a fair
description of the recent NMC data on and at
, as well as the CCFR neutrino data at and . We
also make some reasonable and simple assumptions to relate unpolarized and
polarized quark parton distributions and we obtain, with no additional free
parameters, the spin dependent structure functions and
. Using the correct evolution, we have checked that they
are in excellent agreement with the very recent SMC proton data at and the SLAC neutron data at .Comment: 17 pages,CPT-94/P.3032,latex,6 fig available on cpt.univ-mrs.fr
directory pub/preprints/94/fundamental-interactions /94-P.303
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
- âŠ