1 The Operation of the LHC detectors LPCC student lectures CERN June 29 th 2010 Special thanks to T. Camporesi, C. Garabatos Cuadrado, T. Pauly, W. Kozanecki, S. Wenig Lectures prepared by: T. Camporezi, C. Clément, C. Garabatos Cuadrado, R. Jacobsson, Luca Malgeri, T. Pauly Christophe ClementLHC Lectures – Experiment Operation

2 Experimental Control Rooms ATLASALICE CMS LHCb Christophe ClementLHC Lectures – Experiment Operation

3 Experimental Control Rooms ATLASALICE CMS LHCb Why do we need experimental control rooms? Why do we need experimental control rooms? Christophe ClementLHC Lectures – Experiment Operation

4 Experimental Control Rooms Christophe ClementLHC Lectures – Experiment Operation Experimental control rooms are far from the detector, due to the radiation environment. 1) Monitor and maintain a large industrial complex: electrical systems, cryogenics, gas systems, radiation environment, access restrictions, safety of personel ad equipments 2) Operate and monitor the experiment to maximize performance for physics Operate to maximize quality of data being taken Operate at maximum data taking efficiency

5 Example of Control Room Layout Tracking Detectors Trigger and DAQ EM Cal, HCal endcap Muon Chambers shift leader Infrastructure, safety, access... Manned by shifters 24/7 + experts on-call for each specific task + how many experts and shifters required? Christophe ClementLHC Lectures – Experiment Operation Luminosity Beam conditions HCal

6 Example of Control Room Layout Christophe ClementLHC Lectures – Experiment Operation Data Quality Monitoring Trigger Busy Monitoring Trigger Rates Data Acquisition Status, Global record and trigger rates, trigger setup... LHC Status Run Plan Detector Status Event Display

7 + Accelerator / Experiment Cycle The Activity in the experiments is paced by the LHC machine cycle The shift leader makes sure that the entire detector follows this scheme, gets ready on time,.... Physics Magnet Current Beam Dump Ramp Down Injection Ramp Squeeze, adjust Stable beam Declared Christophe ClementLHC Lectures – Experiment Operation

8 Beam Modes Christophe ClementLHC Lectures – Experiment Operation

9 + 6/4/2016 Prepare for Injection Christophe ClementLHC Lectures – Experiment Operation

10 + Accelerator / Experiment Cycle Prepare experiment for injection! Finish all ongoing activities: calibrations, tests, stop playing! 1 Physics Magnet Current Beam Dump Ramp Down Injection Ramp Squeeze, adjust Stable beam Declared 4 Christophe ClementLHC Lectures – Experiment Operation

11 + Injection Handshake b/w LHC and Experiments operators Big warning sound a la Star Trek When LHC is warning of INJECTION LHC waits for the experiments to be READY Go To SAFE mode at INJECTION Big warning sound a la Star Trek When LHC is warning of INJECTION LHC waits for the experiments to be READY Go To SAFE mode at INJECTION WARNING VETO Christophe ClementLHC Lectures – Experiment Operation

12 + Experiments STANDBY Low bias voltage on the SCT Low HV on Muon system No bias voltage on the Pixel Every experiment has sensitive equipment that needs to go into a safe mode before injection, eg. ATLAS Silicon tracking (pixel, SCT) detectors Muon Chambers (reduced HV) CMS Silicon tracking detectors (pixel, strip)= OFF Muon Chambers (reduced HV) The Zero Degree and CASTOR Calorimeters In this state the LHC team can inject "pilot bunch" GeV, one low intensity bunch ATLAS Christophe ClementLHC Lectures – Experiment Operation SAFE for the experiments ≠ SAFE for the machine UNSAFE for machine=> I> GeV UNSAFE for the experiments *much* earlier Experiment SAFE => IN STANDBY

13 + Eg. ALICE Super-safe/Safe/Eeady states experiment statedescriptionwhendetectors state super-safefurther reduced HV, perhaps LV off collimator set-up, beam losses to be expected standby_conf, beam_tuning, or ready safereduced HVinjection, ramp, flat top, dump beam_tuning or ready unsafefully operationalstable beams, no beams ready Ea ch detector defines the conditions for each state Transitions between states controlled by one single command super-safe, safe => STANDBY Christophe ClementLHC Lectures – Experiment Operation

14 + 6/4/2016 Christophe ClementLHC Lectures – Experiment Operation

15 + PILOT BEAM  Currents in magnets can only change at a certain rate  Higher energy beam is more stiff −> In case of wrong steering of the beam there is time for the system to react and dump the beam (Beam Loss Monitors)  Potentially most dangerous for experiments is initial injection of bunches at 450 GeV  If wrong magnet settings from start or  Combination of hardware problem, bad readings, bad settings... In this case no warning, if a train of bunches is extracted from SPS, Could potentially shoot many bunches directly into sensitive experimental equipment => first injection in an empty machine is done with pilot bunch Christophe ClementLHC Lectures – Experiment Operation

16 Wrong setting of D1 Wrong setting of MCBX MCBX and MCBXA are the inner triplet orbit correctors for the LHC, MCBX (Horizontal-Vertical Dipole Correctors) MCBXA (with nested Sextupole-Dodecapole insert) Extreme Cases for Illustration not up-to-date with latest machine settings.... illustration only! Christophe ClementLHC Lectures – Experiment Operation

17 + Example: ATLAS Beam Conditions Monitor 4 BCM stations on each side of the Pixel detector Diamond detectors Mounted on Pixel support structure at z = +/ cm and r = 5.5 cm Each station: 1 cm 2 detector element + front-end analogue readout Can generate a beam dump 183cm 38 cm Christophe ClementLHC Lectures – Experiment Operation

18 + Completion of Injection Handshake All Experiments in a safe mode=> All experiments READY LHC can inject All Experiments in a safe mode=> All experiments READY LHC can inject Christophe ClementLHC Lectures – Experiment Operation

19 + Eg. Injection Handshake in ALICE Detectors in safe state Injection handshake just started Christophe ClementLHC Lectures – Experiment Operation

20 + Injection Permit Christophe ClementLHC Lectures – Experiment Operation  SAFETY Hardware signal, if FALSE, injection is not permitted  LHC experiments can set it to TRUE or FALSE  For safety of the experiments, the LHC cannot inject unless it is TRUE  At the end of the handshake procedure it is set to true to the experiments  It is set to FALSE at the end of injection to avoid eg. injection during ramp or stable beam ATLAS Injection Permit Key ATLAS Injection Permit Key If Injection permit is removed beam is not dumped Only "pausing injection"

21 + Injection of probe beam protons / bunch Christophe ClementLHC Lectures – Experiment Operation

22 + Accelerator / Experiment Cycle Once beam is injected and circulating, one can start data taking in a "dummy mode" Purpose: make sure data flow is in perfect shape (ATLAS) Cannot be used for physics since: No collisions, Some detectors partially off Special (robust) trigger setup 1 Physics Magnet Current Beam Dump Ramp Down Injection Ramp Squeeze, adjust Stable beam Declared 4 Christophe ClementLHC Lectures – Experiment Operation

23 + Trigger scheme before physics The ATLAS trigger has 3 levels Level 1 = hardware trigger, readout up to 100kHz Level 2 = readout up to ~3kHz Event Filter = readout typically O(200Hz), limited by Tier 0 and offline capability Trigger menu defined by: 1.Trigger items, algorithms, chains 2.Prescales (PS) Christophe ClementLHC Lectures – Experiment Operation L1_EM5 L2_g10_loose EF_g10_loose Level 1 Trigger Level 2 Trigger Event Filter a trigger chain L1 PS L2 PS

24 + ATLAS Trigger scheme before physics By changing prescale one can effectively turn off or on a trigger chain The trigger menu for physics is uploaded at the start of data taking right after injection Use special prescale sets before stable beam - eg. no algorithm using tracks can be run (silicon tracking detectors in STANDBY) - in practice only some Level 1 trigger items are running Trigger menu cannot be changed without stopping the data taking and reconfiguring the DAQ and trigger systems Prescales can be changed while only pausing the triggers, new luminosity block. Christophe ClementLHC Lectures – Experiment Operation

25 + Energy Ramp During the Ramp, the LHC clock frequency changes with time Effect on the detector electronic Some experiments doing calibrations during ramps 2 Physics Magnet Current Beam Dump Ramp Down Injection Ramp Squeeze, adjust Stable beam Declared 4 Christophe ClementLHC Lectures – Experiment Operation

26 + Example of trial ramps (LHC dry run in 2009) During LHC Ramps experimental electronics see varying clock frequency Can sometimes lead to desynchronisation Depending on experiment: => Do not issue triggers during the steepest part of the ramp, up to ~2.7 TeV per beam => Do not run during ramp => Automatic in ATLAS, special application listening to the LHC BEAM MODE If BEAM MODE=RAMP => do not issue any triggers If Magnet currents > 2.7 TeV, resume triggers (automatic) Experiments during LHC Ramps Clock Frequency (Hz) Christophe ClementLHC Lectures – Experiment Operation

27 syste m runfrequenc y durationwhenstate MCHpedestalfill2.5 min.ramp upBEAM_TUNING HMPIDcalibrationfill2 min.ramp upBEAM_TUNING PMDpedestalfill5 min.flat topBEAM_TUNING ZDCpedestalfill4 min.ramp upREADY SSDpedestalfill6.5 min.ramp upREADY SDDinjectorfill4 min.ramp upREADY TOFnoisefill3 min.ramp up/flat topBEAM_TUNING systemrunfrequencydurationwhenstate T0amp_calfill20 min.ramp downREADY, Right B MCHelec. cal.fill25 min.ramp down/adjustBEAM_TUNING EMCALpedestalfill5 min.ramp down/adjustREADY MTRcalibrationfill5 min.ramp downREADY ALICE Calibration runs during LHC ramp-up or flat top Calibration runs during LHC ramp-down (or adjust) Christophe ClementLHC Lectures – Experiment Operation

28 + End of Ramp Up End of ramp: the energy is not changing anymore, but beam is not stable yet LHC operators might squeeze, adjust, carry out various operations Maintain the experimental equipment in STANDBY. 3 Physics Magnet Current Beam Dump Ramp Down Injection Ramp Squeeze, adjust Stable beam Declared 4 Christophe ClementLHC Lectures – Experiment Operation

29 LHC Page-1 If strange – coded (in units of 120 MeV) BUNCHED BEAM INT. FBCT Fast Beam Current Transformer I(B1) – I(B2) TOTAL BEAM INT. DCCT DC Current Transf. Accelerator: Beam Modes Coupling of Beam Permits  LHC ready to receive beam  Intensity < Safe Beam limit  Intensity >  Roman Pots allowed in  Physics  Post Mortem Signal  Christophe ClementLHC Lectures – Experiment Operation

30 + Can monitor the two beams brought into collisions Can monitor the two beams brought into collisions Experiment Beam 1 SideBeam 2 Side Beam positionsBeam angles Collapse beam separation Christophe ClementLHC Lectures – Experiment Operation