RE: Scoring dose angular distributions

Hi Frances
To score the integrated (not energy dependent) dose out of the target
against angle relative to the beam axis (which I assume coincid with the
target axis) the second option you suggest using USRYIELD is more
appropriate. Since you are not interested in the energy dependence of
the dose, one single detector should be sufficient.

Using USRBDX, as you are pointing out you would have to deal with the
normal of each surface, if you are only interested by the dose out of
the downbeam face for example, you could make a dedicated air region
downbeam using the same plane cutting your ZCC for the target then you
could use USRBDX. But I guess you are interested in particles out the
entire target not only one face...

Hope it helped
Joachim

________________________________

From: owner-fluka-discuss_at_mi.infn.it on behalf of Burge, F (Frances)
Sent: Mon 3/16/2009 11:04 AM
To: fluka-discuss_at_fluka.org
Subject: Scoring dose angular distributions

Dear Fluka users,

  I have a very simple geometry consisting of a beam incident on one end
face of a cylindrical target in air. I would like to score fluence
emerging from the target surface in several angular bins, and then plot
the dose equivalent (obtained from fluence using AUXSCORE) against
angle. I am looking for some advice on choosing the most suitable
scoring option:

>From the course notes for USRBDX, I see that it is possible to score
particles/cm2/GeV/sr per primary, as long as the surface area is given
explicitly. So maybe I can use USRBDX with a single energy bin and
multiple angular bins to score fluence in each angular bin. However, it
also says that angles for USRBDX are measured with respect to the normal
to the surface. With the cylindrical target, the normal will change
direction between the end face and the side of the cylinder, so if I use
this method, do I need separate USRBDX cards for the front, rear and
side surfaces of the cylinder (with surface areas set accordingly) ?

Alternatively, can I use USRYIELD with x1 =3D3D polar angle in lab =
frame, x=3D
2
=3D3D energy (only a single bin required), and setting the normalisation
factor WHAT(6) equal to the surface area of the target cylinder ? This
should also give a result in particles/GeV/sr/cm2 per primary, which I
can convert to particles/cm2/angle, and then use AUXSCORE to convert to
pSv/angle. Since the angles in USRYIELD are measured relative to the
beam direction, will this allow me to deal with scoring in all
directions using a single USRYIELD card ?

Any suggestions on these or other options gratefully received,

Frances

Frances Burge
Health Physicist
01235 778269
Diamond Light Source Ltd.
Harwell Science and Innovation Campus
Didcot
Oxfordshire
OX11 0DE
Received on Tue Mar 17 2009 - 14:12:45 CET