Re: HEPEVT format and IBDGenerator bug report

From: Matthew Worcester (mworcest@hep.uchicago.edu)
Date: Tue Oct 11 2005 - 15:39:47 CDT


Hi Chris,

Here is what I think the IBD events are doing, based on the GLG4sim note
on generators:http://neutrino.phys.ksu.edu/~GLG4sim/generator_list.pdf.

Here is one event:

3
99 1 0 0 0 0 0.00558137 0 0 895.62 949.868 1730.6
1 -11 0 0 0.002605 0.00276 0.00189105 0.000510999 0 895.62 949.868 1730.6
1 2112 0 0 -0.002605 -0.00276 0.00369032 0.939565 0 895.62 949.868 1730.6

There are 3 particles, which is given on the first line. After that each
line corresponds to one particle. The first number is ISTHEP, which as
given in the GLG4sim note is:

1 = actual particle tracked by Geant4
2...99 = informational particle, not tracked

So we have, particle 99 = reactor antineutrino (the pdg code should be
-12, but as the particle is not tracked we didn't look it up then). And
the next two particles are e+ and n, respectively. The remaining values
go:

isthep pdgcode daughter1 daughter2 px py pz mass time0 x0 y0 z0

> The important things to notice are that RAT thinks a particle with a invalid
> PDG code exists (this seems like a pointer error) and also the timing. Are
> the times in the HEPEVT IBD file in global time?

We put time0 = 0 for all events, with the hope that (with event_window =
100000000) this would establish one IBD event per GLG4sim event starting
from a relative time of 0. I am learning, however, that things are much
more complicated. For example, GLG4sim usually puts at least two normally
triggered IBD events into one GLG4sim event.

Matt



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