ECAL miscalibration

Complete: 3

Enabling the ECAL miscalibration

The ECAL miscalibration can be simulated in the same way as in the GEANT-based simulation, by retrieving the miscalibration coefficients from a database or by reading one of the miscalibration xml files. The miscalibration is automatically enabled by inserting the following line

  1. In CMSSW_1_6_X: include "FastSimulation/Configuration/data/MisCalibration.cff"
  2. In CMSSW_1_7_X (and later versions): include "FastSimulation/Configuration/data/CommonInputs.cff" instead of include "FastSimulation/Configuration/data/CommonInputsFake.cff"
in your cfg file.

As of CMSSW_1_8_0_pre4, the possibility of applying a systematic bias on the ECAL RecHits energy has been added. In addition, even when a scenario is chosen, it is possible to modify it. This is can be controlled via FastSimulation/CaloRecHitsProducer/data/CaloRecHits.cff, in the "ECALBarrel" and "ECALEndcap" sections or directly with the following replaces:

 replace doMiscalib=true
 replace caloRecHits.ECALBarrel.Refactor = x.x
 replace caloRecHits.ECALBarrel.Refactor_mean = y.y   
 replace caloRecHits.ECALEndcap.Refactor = x.x
 replace caloRecHits.ECALEndcap.Refactor_mean = y.y   

If Refactor is set to 1., the original miscalibration scenario is applied, if it set to 0, no miscalibration will be applied, and if it is set to 2., the miscalibration twice as large as in the original scenario. The Refactor_mean parameter is used to apply a systematic bias. If it set to 1.02, the energy will be 2% larger than usual. In other words Refactor_mean can be used to study the impact of an incorrect energy scale, while Refactor has an impact on the energy resolution. Note the doMiscalib controls the miscalibration of the ECAL and of the HCAL simultaneously. If you want to miscalibrate only the ECAL, the following replace should be added

replace caloRecHits.HCAL.Refactor = 0.

Choosing a miscalibration scenario

The miscalibration scenario can be obtained from the database. It is possible to simulate different scenarios, stored in xml files. See this page for more details. In this configuration, a different configuration file should be included.

include "FastSimulation/Configuration/data/MisCalibration-xml.cff"
The miscalibration scenario can be chosen among a list of xml files. The list of avalaible scenarii (i.e., xml files) can be found here. A tool to generate the xml files corresponding to a given integrated luminosity is also available in this directory, the file thus obtained should be but into your local CalibCalorimetry/CaloMiscalibTools/data directory Once a scenario is chosen, the following replace statement has then to be issued in your cfg file:
replace CaloMiscalibTools.fileNameBarrel = "miscalib_barrel_0.05.xml"
replace CaloMiscalibTools.fileNameEndcap = "miscalib_endcap_0.05.xml"
The tool filling the calibration constant map from the xml files for the endcaps generates a large number of printouts during the initialization ("Null coordinates = x,y,z - Null received"). These warnings can be safely ignored.

Reviewer/Editor and Date (copy from screen) Comments
AndreaGiammanco - 13 Dec 2011 Removed reference to CSA07
FlorianBeaudette - 06 Dec 2007 Described the use of Refactor & Refactor_mean
PatrickJanot - 02 Nov 2007 Documentation for CMSSW_1_7_X
FlorianBeaudette - 23 Oct 2007 Updated the documentation and links
FlorianBeaudette - 10 Jul 2007 Fill in the blanks
PatrickJanot - 10 July 2007 Create template page

Responsible: AndreaGiammanco
Last reviewed by:

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Topic revision: r9 - 2011-12-13 - AndreaGiammanco

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