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 three-level trigger system will select potentially interesting events in order to reduce the readout rate to about 200 Hz. The first trigger level is implemented in custom-built 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.
|Number of pages||6|
|Journal||Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment|
|Issue number||1-2 SPEC. ISS.|
|State||Published - 21 Oct 2007|
- Cosmic-ray data
- Installation and commissioning
- Trigger system