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 =3D polar angle in lab frame, x=
2
=3D 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 Mon Mar 16 2009 - 11:50:54 CET