Status of the ATLAS Level-1 Central Trigger and Muon Barrel Trigger and First Results from Cosmic-Ray Data (original) (raw)

The ATLAS level-1 trigger: Status of the system and first results from cosmic-ray data

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007

The ATLAS detector at CERN's Large Hadron Collider (LHC) will be exposed to proton-proton collisions from beams crossing at 40 MHz. At the design luminosity of 10 34 cm −2 s −1 there are on average 23 collisions per bunch crossing. A threelevel trigger system will select potentially interesting events in order to reduce the read-out rate to about 200 Hz. The first trigger level is implemented in custombuilt electronics and makes an initial fast selection based on detector data of coarse granularity. It has to reduce the rate by a factor of 10 4 to less than 100 kHz. The other two consecutive trigger levels are in software and run on PC farms. We present an overview of the first-level trigger system and report on the current installation status. Moreover, we show analysis results of cosmic-ray data recorded in situ at the ATLAS experimental site with final or close-to-final hardware.

The Level-1 Trigger Muon Barrel System of the ATLAS experiment at CERN

Journal of Instrumentation, 2009

The ATLAS Level-1 Muon Barrel Trigger is one of the main elements of the first stage of event selection of the ATLAS experiment at the Large Hadron Collider. The challenge of the Level-1 system is a reduction of the event rate from a collision rate of 40 M Hz by a factor 10 3 , using simple algorithms that can be executed in highly parallel custom electronics with a latency of order of 1 µs. The input stage of the Level-1 Muon consists of an array of processors receiving the full granularity of data from a dedicated detector (Resistive Plate Chambers in the Barrel). This first stage of the algorithm is performed directly on-detector, while the final stage is performed on boards mounted in the counting room, by the so-called off-detector electronics. The trigger algorithm is executed within a fixed latency, its real-time output is the multiplicity of muon candidates passing a set of programmable p T thresholds, and their topological information. The detector system and the trigger electronics are designed to achieve a safe bunch-crossing identification. In order to optimize design effort and cost, the trigger system integrates also the readout of the detector, with its own requirements on time resolution and overall data bandwidth. We present the

The RPC LVL1 trigger system of the muon spectrometer of the ATLAS experiment at LHC

2004

Abstract The Atlas Trigger System has been designed to reduce the LHC interaction rate of about 1 GHz to the foreseen storage rate of about 100 Hz. Three trigger levels are applied in order to fulfill such a requirement. A detailed simulation of the ATLAS experiment including the hardware components and the logic of the Level-1 Muon trigger in the barrel of the muon spectrometer has been performed. This simulation has been used not only to evaluate the performances of the system but also to optimize the trigger logic design.

The muon spectrometer barrel level-1 trigger of the ATLAS experiment at LHC

2006

Abstract The proton-proton beam crossing at the LHC accelerator at CERN will have a rate of 40 MHz at the project luminosity. The ATLAS Trigger System has been designed in three levels in order to select only interesting physics events reducing from that rate of 40 MHz to the foreseen storage rate of about 200 Hz. The First Level reduces the output rate to about 100 kHz.

Test beam results and integration of the ATLAS level-1 muon barrel trigger

IEEE Symposium Conference Record Nuclear Science 2004., 2004

The ATLAS Level-1 Muon Trigger will be crucial for the online selection of events with high transverse momentum muons and for its correct association to the bunch-crossing corresponding to the detected events. This system uses dedicated coarse granularity and fast detectors capable of providing measurements in two orthogonal projections. The Resistive Plate Chambers (RPCs) are used in the barrel region (|η| <1). The associated trigger electronics is based on a custom chip, the Coincidence Matrix, that performs space coincidences within programmable roads and time gates. The system is highly redundant and communicates with the ATLAS Level-1 trigger Processor with the MUCTPI Interface. The trigger electronics provides also the Readout of the RPCs. Preliminary results achieved with a full trigger tower with production detectors in the H8 test beam at CERN will be shown. In particular preliminary results on the integration of the barrel muon trigger electronics with the MUCTPI interface and with the ATLAS DAQ system will be discussed.

The second level trigger of the ATLAS experiment at CERN's LHC

IEEE Transactions on Nuclear Science, 2003

The ATLAS trigger reduces the rate of interesting events to be recorded for off-line analysis in three successive levels from 40 MHz to 100 kHz, 2 kHz and 200 Hz. The high level triggers and data acquisition system are designed to profit from commodity computing and networking components to achieve the required performance. In this paper, we discuss data flow aspects of the design of the second level trigger (LVL2) and present results of performance measurements.

Performances of the ATLAS Level-1 Muon Trigger processor in the Barrel

2005

The ATLAS level-1 muon trigger will select events with high transverse momentum and tag them to the correct machine bunch-crossing number with high efficiency. Three stations of dedicated fast detectors provide a coarse pT measurement, with tracking capability on bending and non-bending projections. In the Barrel region, hits from doublets of Resistive Plate Chambers are processed by custom ASIC, the Coincidence Matrices, which performs almost all the functionalities required by the trigger algorithm and the readout.

The ATLAS RPC Level-1 muon trigger: design and simulation

2004

The three-levels ATLAS trigger system has been designed to reduce the initial LHC interactions rate from 1GHz to∼ 100Hz in order to allow permanent data storage. This result must be achieved preserving the less probable physics signals against a large background therefore providing a challenge task for the trigger and DAQ system. The Level-1 muon trigger in the barrel region of the Muon Spectrometer is provided by Resistive Plate Chambers (RPC) working in avalanche mode.

The ATLAS LVL1 Barrel Muon Trigger Commissioning with Cosmic Rays

2006

Abstract The ATLAS muon spectrometer, currently in the installation phase, uses dedicated detectors to be able to trigger on high transverse momentum muons in the range 6-20 GeV/c resistive plate chambers (RPC) are equipping the barrel region in the middle and outer station, while precision chambers (monitored drift tubes, MDT) are present also in the inner layer.