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Cool, thanks for tracking this down. It sounds like I need to make some changes in the LHE-StdHep and EGS5-StdHep converters. It looks like this logic is in LcioPrimaryGenerator::generatePrimaryVertexFromMcpCollection()? I think I understand from your description but it's easier for me if I can read the actual code. On Sat, 18 Apr 2015, Graf, Norman A. wrote: > Hello All, > > I think I might understand what is going on with the decay vertices > > in slic. > "Pre-defined" decays in Geant4 are somewhat tricky. > The decay channel and kinematics can be set by pre-defining > the daughter particles. However, the lifetime of the > intermediate decay is set by the time of creation of its daughters. > If that time is zero (which is the default), two things can happen: > > 1.) If Geant knows about the intermediate particle, then it will > throw a decay time from the known intermediate particle > properties. The intermediate particle is propagated for that length > > of time and the (predefined) daughters are created at that time and > > position, with modifications to account for change in direction and energy > loss. (Unless, of course, there was an interaction with material during > that time.) > > 2.) If Geant does not know about the particle (such as a long-lived > A' particle), then the decay time defaults to zero and all the > daughters are created at the point and time of creation of the parent. > > So, in order to get the behavior we want, you need to set the creation > time for all particles correctly. For daughters of intermediate particles > it is the lifetime of the parent. > I hope this is clear. If not, please let me know and I can try to answer > any specific questions. > > > > And the reason why our lcsim code does not correctly read the stdhep > > files is because the "version number" in the begin run record is empty. > > This should be fixed before generating any more events. > > > > Norman > > ######################################################################## > Use REPLY-ALL to reply to list > > To unsubscribe from the HPS-SOFTWARE list, click the following link: > https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=HPS-SOFTWARE&A=1 > ######################################################################## Use REPLY-ALL to reply to list To unsubscribe from the HPS-SOFTWARE list, click the following link: https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=HPS-SOFTWARE&A=1