1. Status of the ATLAS first-level Central Trigger and the Muon Barrel Trigger and First Results from Cosmic-Ray Data David Berge (CERN-PH) for the ATLAS first-level trigger community 15 th IEEE NPSS Real Time Conference 2007 Fermilab, April 29 – May 4

2. IEEE Real Time, May 2007 David Berge 2 ETET bunch-crossing rate Triggering at the LHC -bunch crossing rate: 40 MHz -event size:~ 1.5 MB -would give:~ 60 TB/s -affordable:~ 300 MB/s -storage rate:~ 200 Hz → keep 5 in 10 6 events (reject 99.9995%) -“New Physics” cross sections ~10 6 smaller than total cross section -In 1 second: 2000 W’s, 500 Z’s, 10 tops, 0.1 Higgs (?) storage rate discoveries σ rate e.g. Higgs → ZZ → 2e+2  23 min. bias events: ~ 1725 particles/BC powerful trigger needed enormous rate reduction retaining the rare events in the very tough LHC environment

3. IEEE Real Time, May 2007 David Berge 3 The ATLAS Trigger System ~ 10 ms software hardware 2.5  s ~ sec. 150 GB/s ~4.5 GB/s ~300 MB/s 1)LVL1 decision based on data from calorimeters and muon trigger chambers; synchronous at 40 MHz 2)LVL2 uses Regions of Interest identified by LVL1 (< 10% of full event) with full granularity from all detectors 3)Event Filter has access to full event and can perform more refined event reconstruction

4. IEEE Real Time, May 2007 David Berge 4 Pre-processor Cluster Processor Jet/Energy Processor End-cap Muon Trigger (TGC) Barrel Muon Trigger (RPC) Muon-CTP-Interface (MuCTPI) Central Trigger Processor (CTP) LTP BusyTTC Detector Front-Ends/Read-out LTP BusyTTC Muon DetectorsCalorimeter Detectors Common Merger Modules The ATLAS LVL1 Trigger System

5. IEEE Real Time, May 2007 David Berge 5 The ATLAS LVL1 Muon Trigger Dedicated muon chambers with good timing resolution Barrel (|η|<1.05) : –Resistive Plate Chambers (RPCs) End-caps (1.05<|η|<2.4): –Thin Gap Chambers (TGCs) Local track finding on-detector, candidate multiplicity calculation off- detector Typical RoI size  x  =0.1x0.1 Trigger schema: Two low-p T (6-9 GeV), one high-p T (9-35 GeV) layer Looking for coincidences in chamber layers within programmable roads (road width related to p T ) 6 programmable coincidence windows determine p T threshold (using B-field deflection)

6. IEEE Real Time, May 2007 David Berge 6 The ATLAS LVL1 Muon Barrel Trigger Installation Status: Chamber installation in full swing Final on-detector electronics available Off-detector electronics in production RPCs: most chambers installed, being commissioned

7. IEEE Real Time, May 2007 David Berge 7 The ATLAS LVL1 Central Trigger Muon-to-Central-Trigger-Interface (MuCTPI) Input boards receive muon-trigger inputs from 208 trigger sectors After sector-overlap removal, multiplicities of muon candidates are determined for six p T thresholds Multiplicities are sent to Central Trigger Processor at 40 MHz, sector data to DAQ and LVL2 trigger at <100kHz, per LVL1 accept Demonstrator boards installed –Provide all the required functionalities for commissioning –2 out of 16 input boards (with 14 sector inputs each) are available –Currently there is one muon-barrel trigger sector commissioned –Final boards expected in summer 2007 MuCTPI Crate

8. IEEE Real Time, May 2007 David Berge 8 The ATLAS LVL1 Central Trigger Central Trigger Processor (CTP): Central part of the LVL1 trigger system Final boards installed at the experimental site already 9U VME64x FPGA-based boards, housed in one crate with two dedicated backplanes System consists of –3 CTP_IN Take up to 372 trigger inputs 1 installed at experiment, 7 more available in the lab –1 CTP_MI Machine interface Clock and orbit input –1 CTP_MON Monitors trigger input per bunch crossing –1 CTP_CORE Trigger decision according to configurable menu Send trigger data DAQ and LVL2 –4 CTP_OUT Output to sub-detectors Input of sub-detector busy signals –1 CTP_CAL Handles calibration requests and additional trigger inputs Available late summer 2007 CTP Crate

9. IEEE Real Time, May 2007 David Berge 9 The ATLAS LVL1 Central Trigger Central Trigger Inputs: –multiplicities of e/ ,  /hadrons, jets for 8 p T thresholds each –flags for  E T and missing E T over thresholds –muon multiplicities for 6 p T thresholds –forward and minimum-bias detectors 160 input bits, plus internal bits for random or bunch-group triggers, are combined to 256 trigger items, with 256 configurable pre-scale factors LVL1 trigger decision based on inputs from LVL1 calorimeter and muon trigger systems according to configurable trigger menu The ATLAS trigger configuration system is based on a set of relational database tables and dedicated software; it is a coherent system for all trigger levels, for both online and offline LVL1 Signature Rate (kHz) MU200.8 2MU60.2 EM25i12.0 2EM15i4.0 J2000.2 3J900.2 4J650.2 J60+xE600.4 TAU25+xE302.0 MU10+EM15i0.1 Others5.0 Total~ 25 LVL1 Trigger Menu for 2x10 33 cm -2 s -1 (ATLAS High-Level Trigger TDR, CERN/LHCC/2003-022) See poster ‘The Configuration System of the ATLAS Trigger’, Stelzer et al. (PS2D).

10. IEEE Real Time, May 2007 David Berge 10 In Situ Cosmic-Ray Commissioning Cosmic-ray commissioning runs with Central Trigger and one Muon-Barrel sector started in August 2006 Global ATLAS commissioning effort started in December 2006 with barrel calorimeters and Central Trigger Recently (end of March 2007) combined cosmic-ray run with barrel calorimeters, one barrel-muon sector, and Central Trigger

11. IEEE Real Time, May 2007 David Berge 11 Commissioning with Barrel Muon Detector Cosmic-ray RPC impact points, extrapolated to ground level z (cm) x (cm) ATLAS shafts Plot1: MC Plot2: data Pt from majority settings: Pt1-Pt3 : different coincidences in low Pt planes Pt4-Pt6 : high Pt planes Opened up coincidence settings for maximum acceptance

12. IEEE Real Time, May 2007 David Berge 12 Cross-checks with Cosmic-Ray Data Important data-integrity checks done with cosmics Correlation of MuCTPI data and CTP trigger item Correlation of RPC and MuCTPI thresholds

13. IEEE Real Time, May 2007 David Berge 13 Cross-checks with Cosmic-Ray Data GPS times are available from central-trigger data, the CTP time-stamp assignment works as expected Time difference between consecutive events Correlation of Bunch-Crossing ID difference and time difference of consecutive events 30-60 Hz trigger rate from cosmics 

14. IEEE Real Time, May 2007 David Berge 14 Integration Tests LVL1 – LVL2 LVL2 algorithm reconstructed downward-going cosmic muon candidates online, fully based on RoI mechanism! Reconstructed  of muon tracksReconstructed  of muon tracks

15. IEEE Real Time, May 2007 David Berge 15 Summary The trigger systems are of utmost importance at the LHC The ATLAS first-level trigger system is based on calorimeter data and dedicated muon chambers It reduces the event rate of initially 40 MHz to less than 100 kHz with a latency of less than 2.5  s Parts of the level-1 trigger system are already installed at the experimental site Frequent cosmic-ray commissioning runs with parts of the ATLAS detector are undertaken The test runs prove invaluable for putting the trigger system into operation The first-level trigger will be fully operational for the first p-p collisions end of 2007

16. IEEE Real Time, May 2007 David Berge 16 Backup slides

17. IEEE Real Time, May 2007 David Berge 17 Available Central-Trigger Monitoring Data Decoding 31 64 160 PIT Decoding by bunch 160 PIT Decoding Pre- scale Mask+ Veto 256 TBP 256 TAP 256 TAV CTP_INCTP_MON CTP_CORE Pattern-In-Time (PIT) bus after veto before veto = after pre-scale before pre-scale = Counter = Matrix 160 PIT input signals Max. 372 Input Signals + pre-scaled event monitoring + busy monitoring

18. IEEE Real Time, May 2007 David Berge 18 Commissioning with Barrel Muon Detector Cosmic-ray runs performed with sector 13 (precision + trigger chambers) Muon trigger chambers provided muon candidate data to central trigger Central trigger generated LVL1 accept signal and initiated the readout 30-60 Hz LVL1 trigger rate Verified trigger latency Developed procedures for timing-in the experiment

19. IEEE Real Time, May 2007 David Berge 19 Underground RPC Sector Logic Boards MuCTPICTP Candidates NIM ROS VMEVME RoI Builder RoI Surface L2SV L2PU Dataflow Manager SFI LVL2 Result Handler CTP MuCTPI RPC Dataflow LVL1 (Muon) – LVL2 integration