Problem 1555 - G4Exception - time going back due to decay of sigma-
Summary: G4Exception - time going back due to decay of sigma-
Status: RESOLVED FIXED
Alias: None
Product: Geant4
Classification: Unclassified
Component: processes/decay (show other problems)
Version: 10.0
Hardware: All All
: P5 critical
Assignee: kurasige
URL:
Depends on:
Blocks:
 
Reported: 2014-01-02 18:21 CET by Vladimir.Ivantchenko
Modified: 2014-01-04 07:16 CET (History)
0 users

See Also:

Attachments
macro for Hadr00 (571 bytes, application/octet-stream)
2014-01-02 18:21 CET, Vladimir.Ivantchenko 		Details
output (116.88 KB, application/octet-stream)
2014-01-03 13:49 CET, Vladimir.Ivantchenko 		Details
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Description Vladimir.Ivantchenko 2014-01-02 18:21:58 CET 
Created attachment 250 [details]
macro for Hadr00

Dear Hisaya,

In CMS production in some conditions 80% of jobs are lost due to "time going back" exception. Exception happens when sigma- is selected as a decay on fly but PostStep the energy is zero.

Simple method to reproduce the problem in $G4INSTALL/examples/extended/hadronic/Hadr00

Hadr00 pb.mac QGSP_FTFP_BERT_EMV >& pb1.out

pb.mac and pb1.out are attached.

Cheers,
Vladimir
Comment 1 Vladimir.Ivantchenko 2014-01-03 13:49:22 CET 
Created attachment 251 [details]
output
Comment 2 kurasige 2014-01-04 07:16:37 CET 
Dear Vladimir,

The problem comes not from the status change by AlongDoIt. G4Decay has DecayIt methods for both PostStep and AtRest DoIts. The difference of behaviours between two DoIts is treatment of secondary global time. 
 If the primary track state is changed to 'StopButAlive' by AlongDoIt or other preceding PostStepDoIt, G4Decay misunderstands that the current DoIt is in AtRest and the global time of secondary tracks is set to incorrect values as CMS reported. 

I've added checking track status at the beginning of PostStepDoIt in 'decay-V10-00-00' tag. If the track is set to 'StopButAlive', G4Decay do 'Nothing' and the track will decay at the next step. I've confirmed that the G4Exception disappear. 

Cheers,
	Hisaya