From: Alberto Fasso' (fasso@SLAC.Stanford.EDU)
Date: Tue Jul 24 2007 - 10:37:20 CEST
the recommendations of the FLUKA manual are right in principle,
but a long experience with electron accelerator shielding has
shown that you can get very good results with EMF-BIAS alone.
Apply it EVERYWHERE, and with WHAT(1) = 1022.
You will not need anything else.
On Mon, 23 Jul 2007, Burge, F (Frances) wrote:
> Hello Fluka users,
> I'm looking for some advice on using the biasing options in fluka. My
> input file consists of a 3 GeV electron beam striking a target within a
> shielded enclosure, and I need to score dose rates outside the
> shielding, from photons and neutrons. Without biasing, the run is very
> I guess that for the photons, EMF-BIAS is the appropriate option,
> activated for all processes and with SDUM = LPBEMF. I intended to apply
> this in the target region and also the vacuum surrounding it. However
> the fluka manual recommends avoiding biasing in the scoring region and
> adjacent regions, so should I not apply biasing within the shield wall
> regions ? If I wanted to also score dose rates within the shielding,
> would this mean that I should not use EMF-BIAS in this region either ?
> Also, the manual recommends using the weight window biasing to avoid
> large fluctuations in the dose scoring due to heavily weighted low
> energy particles. So it looks like I also need the WW-THRESh and
> WW-FACTOr cards. Can anyone give me any advice on how to choose the
> upper and lower weight limits of the weight window, or is this only
> possible by carrying out repeated runs on a trial-and-error basis ?
> Finally, would it be safer to use neither of the above options and use
> just the BIASING card instead ? In this case, am I correct in thinking
> that the method would be to divide the target and/or shield wall into
> layers (as different regions) and assign each layer an importance which
> increases with distance through the shield ? Presumably I could also use
> this biasing for neutrons.
> All advice gratefully received.
> Frances Burge
> Health Physicist
> 01235 778269
> Diamond Light Source Ltd.
> Rutherford Appleton Laboratory
> OX11 0DE
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