Random Number Generator not Seeded in GenieHelper tool
The random number generator in the class in nugen responsible for emulating the FNAL beam spill timing is not seeded. This means that all neutrino generation times in a set of MC files will be identical.
The base class implementing the timing is here (nugen:source:nugen/EventGeneratorBase/GENIE/EvtTimeShiftI.cxx#L18) -- the un-seeded random generator is constructed at line 18.
The instance of this virtual class that specializes to the FNAL beam timing is here (nugen:source:nugen/EventGeneratorBase/GENIE/EvtTimeFNALBeam.cxx). It uses the default constructed random number generator and does not update it to be a seeded one.
#1 Updated by Gianluca Petrillo 11 months ago
- Description updated (diff)
That is all true (
TRandom3 is initialised with seed 4357 by default).
Just a reminder that all this machinery is broken anyway because it ignores the correlation between the time of the interaction and the distance of the interaction from the target.
#2 Updated by Robert Hatcher about 1 month ago
- % Done changed from 0 to 100
- Status changed from New to Resolved
While this redmine issue is long outstanding (2019-12-30), I think the fix is as well (made 2020-01-15)
I'd forgotten that this problem was entered as a Redmine issue; updating this to 100% done and resolved. Will close unless I hear feedback otherwise.
#4 Updated by Robert Hatcher about 1 month ago
- % Done changed from 70 to 100
- Status changed from Assigned to Resolved
The corresponding change in GENIEHelper was pushed as https://cdcvs.fnal.gov/redmine/projects/nugen/repository/revisions/e1c43a11e13cc6f5f41d42d3d892388020f2b58e