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geometry magnetic fields simulation trigger calibration reconstruction planning

ZDC Offline code S tatus R eport. Chiara Oppedisano. SUMMARY. geometry magnetic fields simulation trigger calibration reconstruction planning. GEOMETRY. ZDC geometry has been finalized!

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geometry magnetic fields simulation trigger calibration reconstruction planning

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  1. ZDC Offline code Status Report Chiara Oppedisano SUMMARY • geometry • magnetic fields • simulation • trigger • calibration • reconstruction • planning

  2. GEOMETRY • ZDC geometry has been finalized! • Description updated to installed LHC beam pipe volumes and to the ZDC measured positions after installation in LHC tunnel. • Magnet and collimator apertures implemented • the nominal aperture of a collimator (TCTVB) placed on C side still not known • Unfortunately it will becrucial for ZDC physics performances since it could affect ZN acceptance.

  3. MAGNETIC FIELDS ZDC ALICE To correctly track particles from IP to ZDC location compensator, quadrupole and dipole magnetic fields are needed • dipole to compensate the field of the dimuon arm dipole • quadrupole triplet to focalize circulating beams • dipole to separate beams before beam pipes separation 114 m • After the changes in AliRoot magnetic field definition, thanks to Ruben’s help , we also updated the ZDC part of the code. Now machine field are automatically defined: • field values are defined for different beam energy values: • p-p @ 7+7 TeVp-p @ 5+5 TeVp-p @ 450+450 GeVPb-Pb @ 2.7+2.7 TeV •  compensator fields switched on only if ALICE dimuon dipole is on • compensator polarities defined according to ALICE dimuon dipole polarity

  4. SIMULATION (I) • Time information in simulation • Time info added in hits  new AliZDCHit data member fTrackTOF (track TOF in ns) • fTrackTOF ~ 340 ns for hadronic ZDCs • fTrackTOF ~ 20 ns for EM ZDC • Digitization simulates the readout time response  simulation of ADC gate • 70 ns width gate is opened ~ 20 ns before signal • signal shape parameterized from In beam test results • if signal is not completely in the gate, the fraction of lost signal is calculated • New data members in AliZDCDigitizer: • Bool_t fIsSignalInADCGate; • Float_t fFractionLostSignal; •  if (fIsSignalInGate == kFALSE) one can check the fFractionLostSignal value to see how the signal is affected • TO DO •  pile-up simulation to study detector time response

  5. SIMULATION (II) • Simulation of ZDC signal (spectator nucleons) in Pb-Pb interactions • In A-A simulations we “merge” primaries to reduce simulation time: • background(full HIJING without tracking spectators) • signal(spectator nucleons generated with AliGenZDC) • No secondary merging! • In ZDC repository root data files containing spectator hits for each hadronic ZDC: • ZNCSignal.root ZPCSignal.root ZNASignal.root ZPASignal.root • 104events per file • AliZDCDigitizer checks if spectators have been tracked by the generator. • If the generation has been performed using SetSpectator(0), then hits for spectators extracted from the stored files are summed to the HIJING hits in AliZDCDigitizer::SpectatorSignal.

  6. ZN hits ZP hits

  7. TRIGGER • Trigger input to CTP • ZDC trigger provided in A-A collisions: • MINIMUM BIAS trigger • CENTRAL (0-10%) • SEMI-CENTRAL (10-40%) • “special” EMD trigger • Configurable parameters  discriminator thresholds • 5 discriminator thresholds for centrality triggers (MB, C, SC) • 1 threshold value for the summed ZEM spectrum 8 parameters • 2 discriminator thresholds for the EM dissociation trigger • These values can be retrieved from a configuration file saved by ZDC DAQ at run start • Discriminator threshold values don’t have a direct meaning  it could be worth to store in OCDB the corresponding energy values • TO DO •  implement DA, trigger pre-processor, function that produces CTP input from stored OCDB object 0-10 % 10-40 %

  8. CALIBRATION (I) • DAs • Updated DAs: • PEDESTAL DA (new parameters calculated to provide an alternative method for pedestal subtraction) • LASER DA (ZEM output added to monitored signals in LASER calibration runs) • Status: trying to test them with DATE raw data files…BUT I have a problem with root v5.23/02 when fitting histograms  bug submitted to ROOT Savannah one week ago: “problem due to root static libraries and the use of the plug-in manager, investigating!” • As soon as it will be possible to properly test the DAs, I’ll contact ALICE DAQ team for the validation/installation at P2 procedure. • Updated DAs imply small changes in AliZDCPreprocessor and some more data in OCDB stored objects.

  9. CALIBRATION (II) • Info in GRP • Luminosity and collimator apertures values measured by machine luminometers (BRAN) can be very useful. G. De Cataldo contacted. • Already defined DP (to be archived): • dip/acc/LHC/Beam/LuminosityAverage/BRANB.4L2- dip/acc/LHC/Beam/LuminosityAverage/BRANB.4R2- dip/acc/LHC/Beam/LuminosityPerBunch/BRANB.4L2- dip/acc/LHC/Beam/LuminosityPerBunch/BRANB.4R2- dip/acc/Machine/CollimatorPosition/TCDD.4L2- dip/acc/Machine/CollimatorPosition/TDI.4L2- dip/acc/Machine/CollimatorPosition/TCTH.4L2.B1- dip/acc/Machine/CollimatorPosition/TCTH.4L2.B2DP to be defined and stored in archive:TCTV.4L2 TCTV.4R2 TCTVB TCLIA • Run types for which these DP should be retrieved by Shuttle preprocessor: • PHYSICS STANDALONE_EMD

  10. RECONSTRUCTION • AliZDCReconstructor • 2 new data members: • fRecoMode (set = 0 for p-p data or = 1 for A-A data) • fBeamEnergy • In AliZDCReconstructor constructor the function SetRecoMode() is called to properly set fRecoMode. • Beam type and beam energy are read from GRP object or they can be alternatively set through suitable setters. •  an alternative method to subtract pedestal has been added.

  11. PLANNING Deployment of DAs @ P2  waiting for DA working on raw data files (root plugin manager to be solved) Offline calibration  made with macros…further thinking needed QA  I need some clarification…(end of May) Time info during digitization  done  Time information in stored digits  to be done (end of March) Event merging  ??? Scaler in raw data  as soon as it will be added in raw data Field map for different running scenarios  done  Implementation of trigger in simulation  as soon as it will be implemented in ZDC DAQ (end of May)

  12. Backup (I)

  13. Backup (II) • ONLINE CALIBRATION • run types defined for your preprocessor •  STANDALONE_PEDESTAL  STANDALONE_LASER  STANDALONE_EMD  STANDALONE_BC  STANDALONE_COSMIC  PHYSICS • calibration objects(from release v4-13-Rev-06) • ZDC/Align/Data  alignment object from DCS • ZDC/Calib • ChMap/  calibration object containing ADC mapping • EMDCalib/  energy calibration and inter-calibration parameters • LaserCalib/  calibration to take into account fibres ageing effects • Pedestals/  pedestal subtraction coefficients for ADC spectra • RecoParam/  parameters for p-p or Pb-Pb reconstruction

  14. Backup (III) • OFFLINE CALIBRATION • status of the procedures after the Offline October '08 Week Raw data collected in standalone (PEDESTAL, LASER) runs can in principle be re-processed in order to check if the calibration parameters automaticallycalculated are consistent/correct. The procedures will mainly be macros to be run on standalone acquired raw data. These checking procedures will surely be used at the beginning of data taking. • status of the calibration objects • NO new objects needed, eventually some calibration object could be updated after the offline calibration.

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