Problem 1719 - Bug in Zeff computation for sampling calorimeters
Summary: Bug in Zeff computation for sampling calorimeters
Status: ASSIGNED
Alias: None
Product: Geant4
Classification: Unclassified
Component: parameterisations/gflash (show other problems)
Version: 10.1
Hardware: All All
: P5 major
Assignee: Marc.Verderi
URL:
Depends on:
Blocks:
 
Reported: 2015-03-10 10:46 CET by aferrero19752
Modified: 2015-10-02 12:50 CEST (History)
1 user (show)

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Description aferrero19752 2015-03-10 10:46:01 CET 
I've recently started to look into the gflash code and I'm comparing results obtained with geant4 and the original fortran GFlash code.

While doing that, I've noticed that the computation of the effective Z for sampling calorimeters looks suspicious:

  Zeff   = ( W1*Z2 ) + (W2*Z1);    //X0*Es/Ec;
  Aeff   = ( W1*A1 ) + (W2*A2);


My impression is that Z1 and Z2 are swapped in the computation of Zeff. Since Zeff enters in several formulas for the computation of the longitudinal ad transverse shower shapes, I think this bug (if confirmed) could have a major impact on the simulation.


The suspicious line appears in 
source/parameterisations/gflash/src/GFlashSamplingShowerParameterisation.cc
Comment 1 Marc.Verderi 2015-10-02 12:50:57 CEST 
Sorry for the (so) long silence on this.

I agree the Z1 and Z2 are swapped.

The bug report is kept open for now, while making validations.