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Feature #16373

Add a random stream specific for ionisation and scintillation calculations in LArG4

Added by Gianluca Petrillo over 3 years ago. Updated over 1 year ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Category:
Simulation
Target version:
-
Start date:
05/01/2017
Due date:
% Done:

100%

Estimated time:
Spent time:
Experiment:
LArSoft
Co-Assignees:
Duration:

Description

Currently, ionisation and scintillation (IS) calculations draw random numbers from the Geant4 stream.
This means that when IS model is changed or tweaked, Geant4 propagation is also affected.


Related issues

Related to LArSoft - Bug #16344: Scintillation By Particle Type bugClosed04/26/2017

History

#1 Updated by Gianluca Petrillo over 3 years ago

  • Related to Bug #16344: Scintillation By Particle Type bug added

#2 Updated by Gianluca Petrillo over 3 years ago

This has been noticed while studying the effects of solution of issue #16344.
It turns out that OpFastScintillation uses G4Poisson(mean) to get the number of observed photons. G4Poisson() internally uses one of two different algorithms, depending of mean value, which extract a different number of random numbers (1 or 2).
The random stream Geant4 uses for the propagation through matter is the same that G4Poisson() uses, therefore a change in number of scintillated photons can directly affect Geant4 results.
Note that OpFastScintillation is not part of Geant4.

#3 Updated by Lynn Garren over 3 years ago

  • Status changed from New to Assigned
  • Assignee set to Gianluca Petrillo

#4 Updated by Katherine Lato almost 3 years ago

  • Status changed from Assigned to Accepted
  • Assignee deleted (Gianluca Petrillo)

The resolution is affected by the LArG4 work currently being done.

#5 Updated by Hans-Joachim Wenzel almost 2 years ago

In the refactored larg4 the ionisation and scintillation calculations are not done in the geant4 module anymore but they are the first step in the module that calculates the drift of electrons to the wire using the SimEnergyDeposit data product as input. There for the state of the random numbers in geant 4 is not affected.

#6 Updated by Hans-Joachim Wenzel almost 2 years ago

  • Status changed from Accepted to Resolved

#7 Updated by Hans-Joachim Wenzel almost 2 years ago

  • % Done changed from 0 to 100

#8 Updated by Katherine Lato over 1 year ago

  • Status changed from Resolved to Closed


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