5,831 research outputs found
Status and perspective of detector databases in the CMS experiment at the LHC
This note gives an overview at a high conceptual level of the various databases that capture the information concerning the CMS detector. The detector domain has been split up into four, partly overlapping parts that cover phases in the detector life cycle: construction, integration, configuration and condition, and a geometry part that is common to all phases. The discussion addresses the specific content and usage of each part, and further requirements, dependencies and interfaces
Using XDAQ in Application Scenarios of the CMS Experiment
XDAQ is a generic data acquisition software environment that emerged from a
rich set of of use-cases encountered in the CMS experiment. They cover not the
deployment for multiple sub-detectors and the operation of different processing
and networking equipment as well as a distributed collaboration of users with
different needs. The use of the software in various application scenarios
demonstrated the viability of the approach. We discuss two applications, the
tracker local DAQ system for front-end commissioning and the muon chamber
validation system. The description is completed by a brief overview of XDAQ.Comment: Conference CHEP 2003 (Computing in High Energy and Nuclear Physics,
La Jolla, CA
The CMS Event Builder
The data acquisition system of the CMS experiment at the Large Hadron
Collider will employ an event builder which will combine data from about 500
data sources into full events at an aggregate throughput of 100 GByte/s.
Several architectures and switch technologies have been evaluated for the DAQ
Technical Design Report by measurements with test benches and by simulation.
This paper describes studies of an EVB test-bench based on 64 PCs acting as
data sources and data consumers and employing both Gigabit Ethernet and Myrinet
technologies as the interconnect. In the case of Ethernet, protocols based on
Layer-2 frames and on TCP/IP are evaluated. Results from ongoing studies,
including measurements on throughput and scaling are presented.
The architecture of the baseline CMS event builder will be outlined. The
event builder is organised into two stages with intelligent buffers in between.
The first stage contains 64 switches performing a first level of data
concentration by building super-fragments from fragments of 8 data sources. The
second stage combines the 64 super-fragments into full events. This
architecture allows installation of the second stage of the event builder in
steps, with the overall throughput scaling linearly with the number of switches
in the second stage. Possible implementations of the components of the event
builder are discussed and the expected performance of the full event builder is
outlined.Comment: Conference CHEP0
Persistent storage of non-event data in the CMS databases
In the CMS experiment, the non event data needed to set up the detector, or being produced by it, and needed to calibrate the physical responses of the detector itself are stored in ORACLE databases. The large amount of data to be stored, the number of clients involved and the performance requirements make the database system an essential service for the experiment to run. This note describes the CMS condition database architecture, the data-flow and PopCon, the tool built in order to populate the offline databases. Finally, the first results obtained during the 2008 and 2009 cosmic data taking are presented.In the CMS experiment, the non event data needed to set up the detector, or being produced by it, and needed to calibrate the physical responses of the detector itself are stored in ORACLE databases. The large amount of data to be stored, the number of clients involved and the performance requirements make the database system an essential service for the experiment to run. This note describes the CMS condition database architecture, the data-flow and PopCon, the tool built in order to populate the offline databases. Finally, the first experience obtained during the 2008 and 2009 cosmic data taking are presented
Commissioning of the CMS High Level Trigger
The CMS experiment will collect data from the proton-proton collisions
delivered by the Large Hadron Collider (LHC) at a centre-of-mass energy up to
14 TeV. The CMS trigger system is designed to cope with unprecedented
luminosities and LHC bunch-crossing rates up to 40 MHz. The unique CMS trigger
architecture only employs two trigger levels. The Level-1 trigger is
implemented using custom electronics, while the High Level Trigger (HLT) is
based on software algorithms running on a large cluster of commercial
processors, the Event Filter Farm. We present the major functionalities of the
CMS High Level Trigger system as of the starting of LHC beams operations in
September 2008. The validation of the HLT system in the online environment with
Monte Carlo simulated data and its commissioning during cosmic rays data taking
campaigns are discussed in detail. We conclude with the description of the HLT
operations with the first circulating LHC beams before the incident occurred
the 19th September 2008
CMS DAQ Event Builder Based on Gigabit Ethernet
The CMS Data Acquisition system is designed to build and filter events originating from approximately 500 data sources from the detector at a maximum Level 1 trigger rate of 100 kHz and with an aggregate throughput of 100 GByte/s. For this purpose different architectures and switch technologies have been evaluated. Events will be built in two stages: the first stage, the FED Builder, will be based on Myrinet technology and will pre-assemble groups of about 8 data sources. The next stage, the Readout Builder, will perform the building of full events. The requirement of one Readout Builder is to build events at 12.5 kHz with average size of 16 kBytes from 64 sources. In this paper we present the prospects of a Readout Builder based on TCP/IP over Gigabit Ethernet. Various Readout Builder architectures that we are considering are discussed. The results of throughput measurements and scaling performance are outlined as well as the preliminary estimates of the final performance. All these studies have been carried out at our test-bed farms that are made up of a total of 130 dual Xeon PCs interconnected with Myrinet and Gigabit Ethernet networking and switching technologies
Search for charginos in e+e- interactions at sqrt(s) = 189 GeV
An update of the searches for charginos and gravitinos is presented, based on
a data sample corresponding to the 158 pb^{-1} recorded by the DELPHI detector
in 1998, at a centre-of-mass energy of 189 GeV. No evidence for a signal was
found. The lower mass limits are 4-5 GeV/c^2 higher than those obtained at a
centre-of-mass energy of 183 GeV. The (\mu,M_2) MSSM domain excluded by
combining the chargino searches with neutralino searches at the Z resonance
implies a limit on the mass of the lightest neutralino which, for a heavy
sneutrino, is constrained to be above 31.0 GeV/c^2 for tan(beta) \geq 1.Comment: 22 pages, 8 figure
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