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Software for the Heavy Photon Search Experiment

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Subject:
From:
Sho Uemura <[log in to unmask]>
Reply To:
Software for the Heavy Photon Search Experiment <[log in to unmask]>
Date:
Sat, 18 Apr 2015 08:49:57 -0700
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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
>
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