PandoraPFACalibrator Class Reference

PandoraPFACalibrator is a processor to aid calibration of PandoraPFA. More...

#include <PandoraPFACalibrator.h>

Inheritance diagram for PandoraPFACalibrator:

Public Member Functions
virtual Processor *	newProcessor ()
virtual void	init ()
	Called at the begin of the job before anything is read. More...
virtual void	processRunHeader (LCRunHeader *run)
	Called for every run.
virtual void	processEvent (LCEvent *evt)
	Called for every event - the working horse.
virtual void	check (LCEvent *evt)
	Check.
virtual void	end ()
	Called after data processing for clean up.

Detailed Description

PandoraPFACalibrator is a processor to aid calibration of PandoraPFA.

There are three sets of constants that need to be calibrated:
  i) CaloDigi raw hit to GeV
 ii) PandoraPFA energy in GeV -> MIP equivalent conversion
iii) PandoraPFA MIP equivalent -> PFO energy
One might expect that factor iii) is the reciprocal of factor ii). However,
due to the isolation cuts used in PandoraPFA this is not quite the case.

MC Samples:

  o the calibration constants will depend on the Mokka ECAL and HCAL 
    drivers, the GEANT4 physics list, and potentially the version of 
    GEANT4 used to generate the events.
  o to calibrate PandoraPFA generate the following samples with the
    same version of Mokka/Geant4 used for the main event samples:
       o 10000 10 GeV photons with flat phi and flat cosine(theta) distributions
       o 10000 10 GeV K0L with flat phi and flat cosine(theta) distributions
       o 10000 10 GeV mu+/-

Calibration Procedure:

i) Calibration of Mokka hits
  o Using the photon sample, tune the calibration parameters in digitisation processor
    e.g. <parameter name="CalibrECAL" type="FloatVec">XX YY</parameter>
    to so that the histogram fCalEnergy is centred on 10 GeV. It is recommended 
    that the calibration constants for the different layers should be in the ratio
    of the absorber thicknesses, i.e. 1:2 for ILD_o1_v05.
  o Repeat with the 10 GeV KL sample to fix 
    <parameter name="CalibrHCAL" type="FloatVec">ZZ</parameter>
ii) PandoraPFA MIP calibration
  o Using the muon sample, tune the parameters:
    <parameter name="ECALMIPcalibration" type="float">AA</parameter>
    <parameter name="HCALMIPcalibration" type="float">BB</parameter>
    so that fEcalMIPcorr and fHcalMIPcorr peak at approximately one. This
    set the scale for the energy deposited by a "minimum ionizing particle".
iii) PandoraPFA ECAL/HCAL calibration
  o Using the photon sample run PandoraPFA and PandoraPFACalibrator and determine
    <parameter name="ECalToEMGeVCalibration" type="float">XX</parameter>
    <parameter name="HCalToEMGeVCalibration" type="float">YY</parameter>
    so that fPFA peaks at 10 GeV. It is recommended to set the response to
    hadrons to be the same as that for EM showers, i.e. ECalToEMGeVCalibration = HCalToEMGeVCalibration
  o Using the K0L sample, examine the profile of a plot of ECALToHAD energy vs HCALToHAD energy,
    expecting the profile to be a straight line of gradient -1, intercepting both axes at 10GeV.
    However, it may be necessary, for optimal jet energy resolution, to deweight the ECALToHAD contribution.
    Set the parameters below accordingly:
    <parameter name="ECalToHadGeVCalibrationBarrel" type="float">AA</parameter>
    <parameter name="ECalToHadGeVCalibrationEndCap" type="float">BB</parameter>
    <parameter name="HCalToHadGeVCalibration" type="float">CC</parameter>

Member Function Documentation

void PandoraPFACalibrator::init ( )

virtual

Called at the begin of the job before anything is read.

Use to initialize the processor, e.g. book histograms.

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The documentation for this class was generated from the following files:

• PandoraPFACalibrator.h
• PandoraPFACalibrator.cc