RE: collimators

From: Mario Santana Leitner <Mario.Santana_at_cern.ch>
Date: Wed, 14 Oct 2009 18:16:58 +0200

Hi Vitaly,

In order to score which particles are entering or exiting a given object
in your geometry you can use the routine mgdraw.f (http://www.fluka.org/fluka.php?id=man_onl&sub=100). You will need
to include the USERDUMP card (http://www.fluka.org/fluka.php?id=man_onl&sub=82) in your input
file, for example:

USERDUMP 100. 25.0 4.0 1.

and you will have to recompile FLUKA with your customized mgdraw.f (e.g.
$FLUPRO/flutil/lfluka -m fluka -o mgdraw.f).
Note that within mgdraw MREG is the current region and NEWREG is the new
region. Those variables are integers. If you want to obtain the
associated region names you will have to transform the numbers into
names with the GEOR2N routine, for example:
      CALL GEOR2N ( MREG, MRGNAM, IERR1 )
      CALL GEOR2N ( NEWREG, NRGNAM, IERR2 )
Then you can tell mgdraw when to print, what to print (particle code,
statistical importance, position and direction cosines, energy...) and
how to print it (format). For example:
      IF ((mrgnam.eq."BLMAir ".or.mrgnam.eq."BLMAL ").and.
     $ nrgnam.eq."BLMQUA ".and.jtrack.eq.3) THEN
         write(87,'(2G10.5,3G14.7,3G14.8)')
     $ wtrack,etrack,xsco,ysco,zsco,cxtrck,cytrck,
     $ cztrck
      END IF
You should know what each variable means. Here's some help:
          jtrack = particle type (identity number)
          {x,y,z}sco = {x.y,z} points of crossing
          etrack = total energy
          am(jtrack) = mass of the particle
          etrack - am(jtrack)= kinetic energy of the particle
          cx,y,ztrck = direction cosines of the current particle
          wtrack = Weight of the particle
By the way. Don't forget to print the weight of the particle wtrack.

Hope this solves your doubts

Mario

-----Original Message-----
From: owner-fluka-discuss_at_mi.infn.it on behalf of Gostishchev, Vitaliy Dr.
Sent: Wed 10/14/2009 11:33 AM
To: fluka-discuss_at_fluka.org
Subject: collimators
 
Dear FLUKA users,

I would kindly ask you to help me in solution of one problem. We are
going to calculate the passage of the particles through the graphite
collimators in details. This means that we want to know the change of
original particle distribution including particles going directly
through the graphite. There is a certain particle distribution before
the collimator. Then the particles pass mostly through the collimator
slit but part of them pass directly through the collimator material.
Graphite is not so effective as iron in sense of particle cutting. The
radiation length for graphite is about 30 cm only. Therefore, we need
longer collimators but, unfortunately, we have not enough space for
them. We are interested in particles which can come to the transfer beam
acceptance together with antiprotons, for example, pions. Pions have
similar rigidity in our case and theoretically can be transport to the
ring and make some harm there. Could you recommend some proper way to
obtain such a particle distribution after collimator. Do we need some
additional code? The idea is to have a particle distribution before and
after collimator in order to understand how many particles can come to
the septum magnet of the following storage ring. It gives us an
information about possible problems.

Thank you in advance for your assistance.

Best regards,
Vitaliy
Received on Fri Oct 16 2009 - 14:53:48 CEST

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