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The ATLAS experiment at CERN's Large Hadron Collider (LHC) has taken its first data with colliding beams. The LHC aims to deliver an integrated luminosity of 1 fb-1 in the run period 2010/2011 at luminosities of up to 1032 cm-2 s-1, which requires active rejection of events in the trigger system. The muon system is the largest sub-detector of the ATLAS experiment and has the capability to reconstruct...
The Run Control System of the Compact Muon Solenoid (CMS) experiment at CERN's new Large Hadron Collider (LHC) controls the sub-detector and central data acquisition systems and the high-level trigger farm of the experiment. It manages around 10,000 applications that control custom hardware or handle the event building and the high-level trigger processing. The CMS Run Control System is a distributed...
In an optical slow wave structure, even small disorder (e.g., few nanometer roughness) can greatly limit by how much the light velocity is reduced. We derive an analytical result for the slowing factor as a function of (weak) disorder, in agreement with experimental observations.
The CMS Data Acquisition (DAQ) System relies on a purely software driven High Level Trigger (HLT) to reduce the full Level-1 accept rate of 100 kHz to approximately 100 Hz for archiving and later offline analysis. The HLT operates on the full information of events assembled by an event builder collecting detector data from the CMS front-end systems. The HLT software consists of a sequence of reconstruction...
The data acquisition system of the CMS experiment at the Large Hadron Collider features a two-stage event builder, which combines data from about 500 sources into full events at an aggregate throughput of 100 GByte/s. To meet the requirements, several architectures and interconnect technologies have been quantitatively evaluated. Both gigabit Ethernet and Myrinet networks will be employed during the...
The CMS Data Acquisition System is designed to build and Alter events originating from 476 detector data sources at a maximum trigger rate of 100 KHz. Different architectures and switch technologies have been evaluated to accomplish this purpose. Events will be built in two stages: the first stage will be a set of event builders called FED Builders. These will be based on Myrinet technology and will...
The data acquisition system of the Compact Muon Solenoid experiment at the large hadron collider reads out event fragments of an average size of 2 kilobytes from around 650 detector front-ends at a rate of up to 100 kHz. The first stage of event-building is performed by the Super-Fragment Builder employing custom-built electronics and a Myrinet optical network. It reduces the number of fragments by...
Current grid technologies offer unlimited computational power and storage capacity for scientific research and business activities in heterogeneous areas over the world. Thanks to the grid, different virtual organizations can operate together in order to achieve common goals. However, concrete use cases demand a more close interaction between various types of instruments accessible from the grid,...
The data acquisition system of the CMS experiment, at the CERN LHC collider, is designed to build 1 MB events at a sustained rate of 100 kHz and to provide sufficient computing power to filter the events by a factor of 1000. The data to surface (D2S) system is the first layer of the data acquisition interfacing the underground subdetector readout electronics to the surface event builder. It collects...
The CERN Large Hadron Collider (LHC) will collide two counter rotating proton beams. The energy stored in each beam is about 350 MJ. If there is a failure in an element of the accelerator, the resulting beam losses could cause damage not only to the machine but also to the experiments. Within the Compact Muon Solenoid experiment (CMS), a beam condition monitor (BCM) is foreseen to monitor fast increments...
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