Problem 1305 - Unphysical time for particles in shower
Summary: Unphysical time for particles in shower
Status: RESOLVED FIXED
Alias: None
Product: Geant4
Classification: Unclassified
Component: track (show other problems)
Version: 9.5
Hardware: PC Linux
: P2 major
Assignee: kurasige
URL:
: 1344 (view as problem list)
Depends on:
Blocks:
 
Reported: 2012-04-17 10:48 CEST by John Apostolakis
Modified: 2012-08-14 10:48 CEST (History)
3 users (show)

See Also:

Attachments
Slides on time differences between G4 9.4p3 and 9.5p1 (744.49 KB, application/pdf)
2012-04-18 12:09 CEST, John Apostolakis 		Details
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Description John Apostolakis 2012-04-17 10:48:23 CEST 

    


    


      



        
          Comment 1
        

        
          John Apostolakis

        

        
        

        
          2012-04-17 10:59:12 CEST
        

      






I received an email report from Christian Soldner (CALICE) about a problem with timing of hits:

Dear Colleagues and GEANT4 development team!

In my current studies of the timing of energy depositions within hadronic showers I noticed something strange:
Using GEANT4.9.5.p01 I observed calorimeter hits occurring earlier than the time of flight would allow.
Switching to GEANT4.9.4.p03 those hits are not present.

You can find details on this in the slides I attached to this mail.  [JA: I am seeking permission to attach these slides. ] 

For now we will I stick with 4.9.4.p03, but I hope the GEANT team can reproduce and look into this issue.

    


    


      



        
          Comment 2
        

        
          John Apostolakis

        

        
        

        
          2012-04-18 12:09:17 CEST
        

      






Created attachment 159 [details]
Slides on time differences between G4 9.4p3 and 9.5p1

    


    


      



        
          Comment 3
        

        
          John Apostolakis

        

        
        

        
          2012-04-18 12:13:14 CEST
        

      






Christian confirmed that the problem appears with three different physics lists:
  QBBC, QGSP_BERT_HP and LHEP

In particular, in order to be sure that the problem is not related to the slow neutron tracking, he tried LHEP 

The same effect is visible in all physics lists. 

( It can be seen in the slides, in the title of the respective plots. )

    


    


      



        
          Comment 4
        

        
          kurasige

        

        
        

        
          2012-04-30 14:28:23 CEST
        

      






A bug in G4PaticleChange::AddSecondary causes the problem. The local time of the parent track was set to secondaries instead of global time. This G4ParticleChange::AddSecondary is used only by hadronic processes. So, tracks created by hadronic interaction of secondary particles from incident muon have wrong timing.
I've committed the bug fixed tag of track-V09-05-06.

    


    


      



        
          Comment 5
        

        
          kurasige

        

        
        

        
          2012-08-14 10:48:33 CEST
        

      






*** Problem 1344 has been marked as a duplicate of this problem. ***