ALICE Offline Week, March 2009C. Oppedisano

geometry magnetic fields simulation trigger calibration reconstruction planning

ZDC OFFLINE CODE

Status Report

SUMMARY

Chiara Oppedisano

ALICE Offline Week, March 2009C. Oppedisano

GEOMETRYZDC 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 be crucial for ZDC physics performances since it could affect ZN acceptance.

ALICE Offline Week, March 2009C. Oppedisano

MAGNETIC FIELDSTo correctly track particles from IP to ZDC location compensator, quadrupole and dipole magnetic fields are needed

ALICEZDC 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 TeV p-p @ 5+5 TeV p-p @ 450+450 GeV Pb-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

ALICE Offline Week, March 2009C. Oppedisano

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 ZDCsfTrackTOF ~ 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

ALICE Offline Week, March 2009C. Oppedisano

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.root104 events 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.

ALICE Offline Week, March 2009C. Oppedisano

ZN hits

ZP hits

ALICE Offline Week, March 2009C. Oppedisano

TRIGGERTrigger 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 startDiscriminator 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 %

ALICE Offline Week, March 2009C. Oppedisano

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.

ALICE Offline Week, March 2009C. Oppedisano

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.B2

DP 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

ALICE Offline Week, March 2009C. Oppedisano

RECONSTRUCTIONAliZDCReconstructor

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.

ALICE Offline Week, March 2009C. Oppedisano

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

Field map for different running scenarios 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

Implementation of trigger in simulation as soon as it will be implemented in ZDC DAQ (end of May)

ALICE Offline Week, March 2009C. Oppedisano

p-p Pb-Pb

SIMULATION ?signal: spectator nucleonsbackground: HIJING (without spectators)

RECONSTRUCTION signal from ZDCE calibration from simulation?

E in ZDC and Nparticipants provided

CALIBRATION pedestals, laser calibration pedestal, laser, EMD energy calibration

TRIGGER no trigger foreseen for the moment

centrality triggers (MB, C, SC)special trigger (EM dissociation)

Backup (I)

ALICE Offline Week, March 2009C. Oppedisano

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

Backup (II)

ALICE Offline Week, March 2009C. Oppedisano

Backup (III)OFFLINE CALIBRATION

status of the procedures after the Offline October '08 WeekRaw data collected in standalone (PEDESTAL, LASER) runs can in principle be re-processed in order to check if the calibration parameters automatically calculated 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 objectsNO new objects needed, eventually some calibration object could be updated after the offline calibration.