Brem in EGS4
Dave Rogers
Rolf has asked about bremsstrahlung production in EGS4.
The brems routines in EGS4 have been checked experimentally for thick
target yields from a variety of targets. The good news is that the
agreement is very good at the 5-10% level of the measurements, both for the
yield as a function of energy and angle, and the spectra. These are
reported in the papers by Faddegon et al (1991, 1990) in the EGS bibliography
(www.irs.inms.nrc.ca/inms/irs/papers/egs.biblio/egs.biblio.html). In 1993
Faddegon and I also did a careful comparison to ITS and found some
differences, again at the 10% or less level.
EGSnrc uses the same total cross-sections as EGS4 with IAPRIM=1, but also
introduced the possibility to sample from the differential photon
cross-section from NIST. This can be more important for the lower
energy photons. We also find some EGS4-EGSnrc differences (10% level)
in the angular distributions of photons from 10-20 MeV electron beams
on thick targets. This is presumably due to electron transport issues.
There is an extensive review of EGS4-EGSnrc differences available in
PIRS-703 (QA tests of the EGSnrc system and comparisons with EGS4)
which is available at www.irs.inms.nrc.ca/inms/irs/EGSnrc/manuals.html.
Ciao
Dave
> From owner-...@SLAC.Stanford.EDU Thu Aug 1 01:36:09 2002
> Return-Path: <owner-...@SLAC.Stanford.EDU>
> Path: listserv.slac.stanford.edu
> Date: Thu, 01 Aug 2002 07:35:01 +0200
> From: Rolf Behrens <Rolf.B...@ptb.de>
> Subject: Bremsstrahlung
>
> Dear all,
>
> dose anyone have information about how good EGS4 is at
> calculating the amount of bremsstrahlung at low Z media?
>
> I am simulating a special device for the measurement of electrons
> and photons. In the calculation, the bremsstrahlung produced in a
> block of PMMA (Plexiglas, Lucite, Perspex) of about 7cm in
> diameter and 4cm in thickness is of special interest. I am
> calculating the dose produced outside of this block.
>
> The electron energy range is from about 10keV to 100MeV; the
> most interesting range is from 0,5MeV to 20MeV.
>
> I am using the ICRU-37 radiative stopping powers (IAPRIME=1).
> In addition, I am using the improved bremsstrahlung photon angular
> sampling (IBRDST=1).
>
> Any comments are appreciated, even crude upper borders of the
> errors that are made by EGS4. Unfortunately, there are no detailed
> information about this item in the manual or in the lectures from an
> EGS4 training-course I attended in 1998.
>
> Best regards
>
> Rolf
>
> Fachlaboratorium 6.31 "Orts- und Personendosimetrie"
> Physikalisch-Technische Bundesanstalt
> Bundesallee 100; D-38116 Braunschweig
> GERMANY
> Tel: +49(0)531/592-6212; Fax:-6015
> E-mail:rolf.b...@ptb.de
> http://www.ptb.de/de/org/6/_index.htm
> Fachlaboratorium 6.31 "Orts- und Personendosimetrie"
> Section 6.31 "Area and personal dosimetry"
>
--
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D.W.O. Rogers phone: 613 993-2715
IRS/INMS Bldg M-35 fax: 613 952-9865
National Research Council of Canada e-mail da...@irs.phy.nrc.ca
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