RE: Using DOSE-EQ with USRYIELD

In principle if you want to calculate fluence or yield of particles from
region 1 to region 2 you have to normalize by the total boundary
surface, otherwise you won't get the proper normalization per cm2;
suppose reg 1 is a small cylinder and reg 2 a sphere, then the boundary
surface is side+both cylinder ends, and that's correct because you are
scoring contribution to fluence (or yield) in each direction.
If, instead, reg 1 and reg 2 are both cylinder with one common end, that
end is the boundary, and that is the surface to take into account.
I hope it answers your question

Lucia

On Mar 27, 2009 11:41 AM, "Burge, F (Frances)"
<frances.burge_at_diamond.ac.uk> wrote:

> Thanks for confirming that - just one more question:
> Since the fluence has a dependence on (1/cos theta), where theta is
> the
> angle between the particle track and the normal to the surface it is
> crossing, this must mean that I have to consider each of the end
> surfaces and the side surface of the lead cylinder separately, so for
> particles escaping the target through its end, I should only normalise
> by the area of that end, and so on.
>
> I am a bit confused by this, because in the previous course notes, the
> USRBDX example shows normalisation of fluences over the total area of
> the side and end faces of a cylindrical target:
> http://www.fluka.org/content/course/NEA/lectures/Scoring.pdf (on page
> 12)
> Won't this result in an underestimate, because it does not take
> account
> of which surface the particles are crossing ? It seems strange that
> particle fluence through the end of the target should be normalised by
> a
> surface area which includes the sides of the target.
>
> Frances
>
> -----Original Message-----
> From: Lucia Sarchiapone [mailto:Lucia.Sarchiapone_at_lnl.infn.it]
> Sent: 26 March 2009 15:56
> To: Burge, F (Frances)
> Cc: fluka-discuss_at_fluka.org
> Subject: Re: Using DOSE-EQ with USRYIELD
>
> Your card combination is correct,
> so if you use the surface of the boundary between "LeadTarg" and
> "Outervac" as normalization factor you will get pSv/GeV/sr per primary
> particle.
>
> Lucia
>
>
> On Mar 24, 2009 03:59 PM, "Burge, F (Frances)"
> <frances.burge_at_diamond.ac.uk> wrote:
>
> > Dear Fluka users,
> > I would like to use the USRYIELD card together with AUXSCORE to
> > convert a photon fluence yield to dose equivalent around a lead
> > target.
> > So I have set up the following cards in my input file:
> >
> > USRYIELD 124 DOSE-EQ -24 LeadTarg Outervac 1.0 Flu_dos1
> > USRYIELD 180. 0. 180. 3. 0. 6. &
> > AUXSCORE USRYIELD PHOTON Flu_dos1 EWT74
> >
> > My first USRYIELD variable is lab polar angle in degrees, from 0 -
> > 180, the second is particle energy with a single bin. I want to
> > score
> > dose equivalent in each of the angular bins if that is possible. The
> > target is simply a ZCC, and the primary beam is travelling along the
> > z
>
> > axis.
> > The quantity scored in USRYIELD is a double differential fluence
> > yield, which if I was just scoring photons (rather than dose-eq)
> > would
>
> > be [photons/GeV/sr/cos theta].
> >
> > Now I guess what I get from the above cards is something like
> > [pSv.cm2
>
> > /GeV/sr] because of the folding of the dose coefficients with the
> > fluence scoring.
> >
> > So the question is: If I normalise to the surface area of the lead
> > target, will I be scoring the correct dose angular distribution in
> > pSv/GeV/sr ? Or is the above combination of cards meaningless ?
> >
> > thanks for any suggestions,
> > Frances
> >
> > Frances Burge
> > Health Physicist
> > 01235 778269
> > Diamond Light Source Ltd.
> > Harwell Science and Innovation Campus
> > Didcot
> > Oxfordshire
> > OX11 0DE
> >
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Received on Mon Mar 30 2009 - 23:41:09 CEST