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Between LHC and the Grid - Aspects of Operating the LHC Experiments –

Between LHC and the Grid - Aspects of Operating the LHC Experiments – T. Camporesi , C.Clement , C. Garabatos Cuadrado , L. Malgeri , T. Pauly , R. Jacobsson. LHC Accelerator*. Physics Analysis. ALICE. Experiments. ATLAS. CMS. LHCb. *Already opened by Stefano Radaelli :

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Between LHC and the Grid - Aspects of Operating the LHC Experiments –

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  1. Between LHC and the Grid - Aspects of Operating the LHC Experiments – T. Camporesi, C.Clement, C. GarabatosCuadrado, L. Malgeri, T. Pauly, R. Jacobsson LHC Accelerator* Physics Analysis ALICE Experiments ATLAS CMS LHCb *Already opened by Stefano Radaelli: http://indico.cern.ch/conferenceDisplay.py?confId=87720

  2. The Scene Experiments have never in the past been so tightly connected to the accelerator What’s so special about LHC? • Stored energy 2 x 360 MJ and fragile detectors • Experiment protection • Operational communication and procedures •  Reliability requires direct communication interfaces • High interaction rate and large events size • Fast and reliable readout, storage and transfer to offline processing • Fast feedback from Data Quality checking • High intensity proton collider and sensitive detectors • Monitoring and understanding/analyzing/optimizing experimental conditions • Luminosity determination • Long-term detector stability and aging due to radiation • Automatic Calibrations • Many years of 24h operation with few people and non-experts • Operating the whole detector from one console • Understandable high-level tools for diagnostics, alarms and data monitoring • Homogeneity in the system • Shifter training These lectures will describe largely how we have addressed and solved these

  3. Protecting Experiment and Data • At all levels we need tools to predict, prevent, and limit “non-bb” exposure • Framework to combine information and understand correlations between background, beam characteristics and machine settings  Dedicated archiving and analysis tools • We need to look at the entire LHC machine Machine settings Beam characteristics Halo/beam-gas/………………....…….scraping……………....Beam incident Background Instantaneous damage ………….…………Trigger rates…………………… ………...………..Poor data quality………………… ……………………..….Single event upsets………. …………..……Accelerated aging……….………… …………………Long-term damage……………..... Luminosity and Background Accumulated dose Beam Interlock Online monitoring

  4. Operational Interfaces

  5. Readout Architecture

  6. RO Control/Event Management Readout Supervisor Bookkeeping DB Configuration DB High Level Trigger Farm • Readout Supervisor is the intelligent readout controller • The “Orchestra Director” • Completely based on Field Programmable Gate Logic devices • Pool of RSs for autonomous stand-alone running of any subdetector Beam Phase and Intensity Monitor Subdetectors LHC accelerator Clock/orbit, UTC, LHC Info Filling Scheme Lumi Scan L0 trigger Bunch currents Filling scheme L0 Decision Detector status Timing/Synch.ctrl HW and run parameters FE Electronics Timing/Synch.ctrl Timing/Synch.ctrl Run statistics Online Luminosity Trigger Throttle RO Electronics RS Event Bank Multi Event Requests

  7. Online Run Performance and Data Quality Calib • Detector Performance, Readout Performance and Data Quality • Histogram collected from all systems • Monitoring Farm spying on event streams at best effort • Also produces histograms from an online reconstruction at best effort • Histogram analysis Automatic checks and alarms • Histogram inspected by Data Manager Shifter Automatic Histogram Analysis Interactive Presenter Histogram Handling (ECS) HISTO DB

  8. Sketchy Offline Data Flow Bookkeping Express Stream HLT Bulk Stream Run Info Online 35 kB/evt@2kHz = 70 MB/s or 2 GB file(~60 kevts) / 30s 5 Hz Offline Storage (CASTOR) Storage (CASTOR) Reconstruction Reconstruction 20h/file, 20 kB/evt Calibration Alignment Tier-0 / 1 QC QC Data Quality Stripping Analysis Test Jobs Data and Production Management Data Quality Checking Simulation Tier-2 Offline Control Room

  9. Fill Procedure • Typical Physics fill cycle • “Machine Development” (MD) periods • Some scheduled days/weeks the LHC will be operated not to produce physics data (Stable Beam) but to study machine physics and improve performance • LHCb will not take data, but safety should be ensured. A shift crew will be needed still, but with lower activities.

  10. Centralized Readout Control Calib • Readout control has two aspects: • Control of data transfer • MEP Packing • Destination assignment for event building and HLT • Load balancing • Partitioning for parallel activities • Management of event types and associated destinations/processing • Physics triggers • Calibration triggers • Luminosity triggers • Non-zero suppressed data • Luminosity scans (Vernier scan) • Driven and managed by the LHCb Timing and Fast Control System • Responsible for distributing timing, trigger and synchronous and asynchronous information to entire readout system • FPGA based master: Readout Supervisor • Also performs rate control and generates all types of auto-triggers and calibration sequences

  11. Accelerator vs Beam Modes

  12. Beam Modes for Physics • In LHCb we synthesize Machine/Beam modes into 9 “Internal LHC States” • INJECTION, RAMP, PHYS_ADJUST, PHYSICS, ADJUST, DUMP • EOF (End-Of-Fill), NO_BEAM, MD (Machine Development) VELO allowed IN • Software “handshakes” between LHC and experiments • INJECTION, ADJUST and BEAM DUMP

  13. LHC/LHCb Operational Procedure Fill sequence for physics fill in LHCb language: NO_BEAM (Injection Permit = FALSE, Any state of LHCb, Internal clock) INJECTION (Injection Permit = TRUE, VELO out, External clock) RAMP (Injection Permit = FALSE) PHYS_ADJUST PHYSICS (VELO in) (ADJUST) (VELO out) DUMP (VELO out, to be changed) EOF (Internal Clock, Calibrations) Handshake for Injection Handshake for Adjust Handshake for Dump (Only when directly from PHYSICS)

  14. Mode Handshake (Ex. Injection) LHC: NO_BEAM INJECTION RAMP STANDBY READY OK WARNING IMMINENT STANDBY LHCb: PROBLEM READY VETO PREPARE Confirm Confirm VETO GET READY READY Experiment Control System  General rule: Get ready in ~5 minutes

  15. No Beam System Tests • Real-Time scheme to validate High Level Trigger, data flow and offline processing = • Be ready to receive, process and analyze 7 million events in the first hour of collisions • Replacing detector with injection of 108 “accepted” simulated events real-time in Online system at HLT rate (2 kHz) • Also allows testing new HLT versions with minimum bias events LHCb Injector Simulated events MEP Requests

  16. Commissioning LHCb • Two years of intense work 2006 – 2008 with the aim to: • Operate the detector AND people as a unit with common tools • Bring all components (sub-detectors and service systems) to operational state. • Define, implement and validate the tools and procedures needed to run the detector as a whole • Organise the activities to reach the ready state in time • Understand and calibrate the detector • Test pulses, radioactive sources • Cosmics • LHC injection tests • First days with beam • Operate with two shifters • Operating the whole detector from one console • Understandable high-level tools for diagnostics, alarms and data monitoring • Homogeneity in the system • Shifter training • On-call Experts for all sub-systems and sub-detectors • Reach operational efficiency • Starting (<10min) and restarting (<1 min) rapidly and smoothly • Actually all achieved for pilot run 2009! • Crucial tool: • Readout and processing of sets of consecutive 25ns clock cycles around “detector activity” trigger • Time and space alignment • Leakage in preceding and subsequent clock cycles • Optimize signal over spill-over 16

  17. Alignment • LHCb did use cosmics but for obvious geometrical reasons not sufficient… • Beam 2 dumps on injection line beam stopper (TED) ideal.. But backwards…! Vertex Locator Muon TI8 TED LHC Scintillator Pad Detector

  18. Beam Gas events • Ideal for monitoring bunch profiles, opimization and absolute luminosity Beam-beam Beam 2 Beam 1 Beam 1 Beam 2 Beam-beam predicted from beam-gas

  19. LHCb Vertex Locator 30 mm 30 mm +/-5 mm Beam • VELO is a Movable Device: • Out position: 35mm from beam line • In nominal data taking position: 5mm from beam line • Data taking position determined during Open Tracking by determining luminous region before moving in for every fill • May only leave its “garage position” during STABLE BEAM 19

  20. LHCb Baackground Monitoring • LHCb Main Background Monitor (BCM) • Diamond based Beam Condition Monitor • Running sums 80ms and 1280ms • Directly connected to LHC Beam Dump System (LBDS) • Also hardware interface for Injection Permit • High-sensitivity and high time resolution monitor • Scintillator based Beam Loss Monitor • 25ns integration and fast readout • Used mainly to understand background and discover problems early (collimator settings, aperture, beam-gas, injection etc) BCM 20

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