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

G Aielli,A Di Girolamo,V Canale,G Chiodini,N Ellis,H Iwasaki,S Tanaka,M Primavera,R Spiwoks,M Nomachi,G Iacobucci,B Liberti,A Nisati,C Omachi,N Lupu,E Petrolo,T Kuwabara,Y Yamaguchi,T Kadosaka,F Grancagnolo,F Pastore,E Etzion,R Vari,P Giusti,D De Pedis,S Antonelli,S Haas,R Perrino,F Marchese,R Santonico,K Nagano,P Farthouat,S Spagnolo,P Iengo,N Kanaya,S Rosati,L Zanello,A Polini,A Messina,M Tomoto,D Caracinha,S Patricelli,G Carlino,S Ask,A Salamon,T Pauly,D Boscherini,M Nozaki,S Veneziano,G Mikenberg,K Kawagoe,J Haller,T Kawamoto,E Gorini,F Spila,Y Hasegawa,A Diciaccio,Y Yasu,T Kohno,C Fukunaga,L Bellagamba,S Bressler,A Di Mattia,F Conventi,A Krasznahorkay,V Izzo,T Wengler,O Sasaki,S Tarem,R Cardarelli,O Bahat Treidel,H Sakamoto,E Solfaroli,M Pectu,A Roich,M Dogaru,T Sugimoto,A Ochi,C Luci,M R Coluccia,T Niwa,T Takeshita,M Perantoni,G Ciapetti,R Lifshitz,D Lellouch,A Bruni,A Aloisio,G Sekhniaidze,E Pasqualucci,E Kajomovitz,Y Sugaya,P Camarri,H Kurashige,M G Alviggi,H Oshita,S Constantin,G Bruni,M Bianco,H Kiyamura,T Kobayashi,M Ikeno,Y Okumura,M Ishino,P Klofver,Y Benhammou,C C Ohm ,Yasushi Takahashi ,M Biglietti ,J Seixas ,M Della Pietra ,Takeshi Kubota ,D Berge ,Antimo Migliaccio ,G Schüler ,D Della Volpe ,R De Asmundis ,H.p Lima ,L J Levinson ,P Gällnö ,Hiroshi Nishimura ,S I Buda ,S Ben Amii ,Hiroshi Takeda

doi:10.1109/tns.2007.910676

Abstract

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 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.

Highlights

The event selection at the Large Hadron Collider (LHC) is a very challenging task
In case of a LVL1-accept signal (L1A) the muon-candidate data is sent to the DAQ system at a maximum rate of 100 kHz, to be included in the ATLAS data stream, and to the LVL2 trigger as RoIs
The Central Trigger Processor (CTP) derives the LVL1 trigger decision based on the information received from the calorimeter and muon trigger systems and potentially input from forward and minimumbias detectors

Summary

INTRODUCTION

The event selection at the LHC is a very challenging task. At the design luminosity of 1034 cm−2 s−1 there are on average 23 collisions per bunch crossing. That is, a trigger system, has to be set in place to reduce the incoming rate to an affordable level of 100-200 Hz (aiming at a data rate of ∼ 300 MB/s) while retaining potentially interesting physics events. ATLAS has designed a three-level trigger system which has the demanding task of finding the five in one million events that can be recorded. It aims at selecting as efficient and unbiased as possible the interesting physics events and is largely based on signatures of high-transverse-momentum particles and large missing transverse energy.

Data recording

LTP TTC Busy high p T

RPCs vs

Findings

CONCLUSIONS