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

The ATLAS detector at CERN's Large Hadron Collider (LHC) will be exposed to proton-proton collisions from beams crossing at 40~MHz. A three-level 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 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 central trigger and the muon barrel 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 ATLAS trigger - high-level trigger commissioning and operation during early data taking

The ATLAS experiment is one of the two general-purpose experiments due to start operation soon at the Large Hadron Collider (LHC). The LHC will collide protons at a centre of mass energy of 14~TeV, with a bunch-crossing rate of 40~MHz. The ATLAS three-level trigger will reduce this input rate to match the foreseen offline storage capability of 100-200~Hz. This paper gives an overview of the ATLAS High Level Trigger focusing on the system design and its innovative features. We then present the ATLAS trigger strategy for the initial phase of LHC exploitation. Finally, we report on the valuable experience acquired through in-situ commissioning of the system where simulated events were used to exercise the trigger chain. In particular we show critical quantities such as event processing times, measured in a large-scale HLT farm using a complex trigger menu

Cranial reconstruction after a post-craniotomy empyema.

International audienceThis article presents a case report of a cranioplasty performed after a post-craniotomy empyema with osteitis. The skull reconstruction was performed using a bioceramic implant and a combined muscular free flap of latissimus dorsi and serratus anterior. This procedure not only provided coverage of a wide skull defect but also allowed the filling of the intracranial dead space. Clinically, we observed an improvement of the patient's preoperative neurological status with a near-complete correction of her right hemiparaesis and phasic disorders. Eight months after the cranioplasty, (1) no recurrence of infection was noticed; (2) no distortion of the skull was noticeable and (3) the patient again experienced a normal social life. Using computed tomography (CT) scan images, we observed a re-expansion of the left cerebral hemisphere without any dead space or extradural collection. The only observable sequelae were a temporoparietal alopecia (10 cm x 4 cm) and a winging of the scapula, induced by the skin graft and the removal of the lower-third of the serratus anterior muscle, respectively. The use of a muscular free flap associated with a customised biomaterial allows a single-stage reconstruction of extensive skull defect (120 cm(2)) in a previously infected area

Measurement of hadron and lepton-pair production at 161 GeV<root s<172 GeV at LEP

Contains fulltext : 26256.pdf (publisher's version ) (Open Access

The ATLAS LVL1 barrel muon trigger commissioning with cosmic rays

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/cResistive 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. The RPCs have the required timing and spatial resolution of about 2 ns × 1 cm, to be able to associate the muon to the correct bunch crossing and provide the second coordinate measurements to the MDTs. In order to successfully commission the chambers, cosmic runs are taken to check and validate the readout and trigger chain, and cosmic rates are measured and compared against values obtained with a cosmic ray Montecarlo generator and full detector simulation. The first part of the detector under commission is the set of horizontal chambers positioned between the feet of the detector. The first results obtained in the ATLAS cavern will be presented. The first cosmic data taking collects signals from chambers arranged in six trigger towers, covering about one quarter of the full detector lenght. The experience gained on this small part of the detector will be very useful to define the commissioning work for the whole detector. © 2006 IEEE

Status of the ATLAS level-1 central trigger and muon barrel trigger and first results from cosmic-ray data

The ATLAS detector at CERN's Large Hadron Collider (LHC) will be exposed to proton-proton collisions from beams crossing at 40 MHz. A three-level 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 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 104 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 central trigger and the muon barrel 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. RI Perrino, Roberto/B-4633-2010; Kurashige, Hisaya/H-4916-2012; Veneziano, Stefano/J-1610-2012; spagnolo, stefania/A-6359-201