Tracklength scoring with USRBIN

From: Chris Theis <>
Date: Wed, 1 Oct 2008 10:58:53 +0200

Dear all,

I'm currently facing some problems where I would need some more detailed
information about the scoring mechanisms of the code. Any hints to solve
the following issue would be greatly appreciated.

Recently I've developed a number of routines that extended the USRBIN
card in order to score fluence spectra with a specified energy
resolution instead of the integral value. The aim was to obtain a
scoring method which is independent of geometry regions in contrast to
the USRTRACK card.

For this purpose I defined a number of 1-bin USRBIN detectors at a
certain location and then used FLUSCW to interface some of my own
book-keeping classes. A number of cross-checks of the obtained fluence
spectra with those from the USRTRACK card showed nice agreement.
However, when I removed the geometry region which was required for the
USRTRACK card and re-ran the simulation the fluence spectra obtained by
my USRBIN extensions suddenly changed. I basically obtained the same
spectral shape but the absolute values were shifted.

After an extensive number of tests I came to the conclusion that this
behavior should be caused by a shift in the tracklength values that are
passed to FLUSCW. From my understanding FLUSCW is called by the
applicable USRBIN detector (USERWEIGH WHAT(3) =3D 3.0) but the
passed is the total tracklength and not the part which traverses the
actual volume of the USRBIN detector. Due to the presence of a vacuum
region, which I used for scoring in my tests, these two values
accidentally coincided as the USRBIN and the geometry region had
identical extensions and placement.=20

This leads me to the question whether there is the possibility to obtain
the actual tracklength within the respective USRBIN as FLUKA needs to
have this information available for its own scoring, and how to do it?
Of course I could extract part of SimpleGeo's own tracker and interface
it to obtain the appropriate portion of the total tracklength. However,
I'd like to avoid this situation if possible. On one hand it would
introduce unnecessary complexity and on the other hand it would entail a
runtime penalty as basically the same calculations, which have been done
by FLUKA already, have to be repeated by myself a second time.

Any help on this matter would be greatly appreciated!

Best regards

Chris Theis
CERN/SC-RP - European Organization for Nuclear Research
1211 Geneva 23, Switzerland
e-mail: www:
Received on Wed Oct 01 2008 - 12:58:55 CEST

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