Re: BXDRAW - tag for beam particles?

From: Giuseppe Battistoni <>
Date: Mon, 28 Sep 2009 11:53:36 +0200

Dear Olaf
Please send your input and routines. LTRACK should not be zeo.
In any case let me add some additional comment about LTRACK, the
generation number.
For primary particles LTRACK = 1. After each interaction, all exiting
have the generation number increased by 1. Here we might enter into a
subtle discussion
Generation number is increased by 1 at all interactions, including
elastic ones.
Therefore asking for LTRACK = 1 is equivalent to ask for particles that
had no interaction at all.
In reality (experiment) you would call "beam particle" a particle having
almost the same
energy and direction of the beam. The risk (depending on your needs) is
you migh fall into a selection which results academic when compared to
real life. For instance
think of a primary muon which undergoes a "small" bremmstrahlung event,
in which its direction
and energy are negligibly changed. In an experiment you will probably
call it a "primary muon",
but in the code it will have LTRACK > 1.
Therefore it is up to you to decide if this selection is what you need
or not.

 Olaf Hartmann wrote:
> Dear listmembers,
> I've a question concerning the BXDRAW entry in mgdraw.f. Is there a
> possibility to access the information whether a particle crossing the
> border out off the target is a beam particle (which did not interact in
> the target)? So far I do this by checking whether the momentum is still
> that of the beam particles. In this way I've to recompile mgdraw each
> time the incident momentum changes.
> I thought I could use the MTRACK variable in TRACKR, but it's always
> zero for all particles.
> Kindly,
> Olaf.
Received on Mon Sep 28 2009 - 12:30:37 CEST

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