multiple and single scatterings

From: Rollet Sofia <>
Date: Mon, 16 Nov 2009 11:53:05 +0100

Dear FLUKA experts,
As I wrote some time ago, I found some discrepancies between the microdosimetric
spectra simulated by FLUKA compared with measurements done with a miniaturized
Tissue Equivalent Proportional Counter. As kindly suggested by Alberto Fasso',
a better agreement is achieved if the single scattering (SS) treatment is used
everywhere instead of only at the boundaries between the gas chamber and the
surrounding A150, as I was using previously (see attached figures).

I can make the calculation with SS everywhere for photons but if I do the same
with protons (E=62 MeV) the CPU time becomes unacceptably long. So the
question is: how do I implement the SS only in certain materials?

Reading the manual, I understand that if I want the single scattering everywhere
with maximum accuracy I should write, for example:

MULSOPT 0. 0. 0. 1. 1. 99999.GLOBAL

and this work, but instead, if I want the SS in two materials only (GAS and A150)
I have problems to understand how to write the card.
For example, requesting 10 SS for hadrons and 100 SS for
electrons -->I0 I1-1= 10, I2-1= 100 --> WHAT(1)= 1+(11*10)+(101*100000)100111
I tried to write:

MULSOPT 10100111 3. 3. GAS A150 1.
And this doesn't work since there are only multiple scatterings in the output.

(- I am not sure of the meaning of "number of single scattering steps" in WHAT(1).
If they are "steps" than it should refer to multiple scatterings or if it
is the number of single scatterings is not a "step"?
-I am not sure if WHAT(2) & WHAT(3) should be =3 and hence completely suppress
the multiple scattering ?
- I am not sure of what SDUM should I write, since I don't want the GLOBAL
and I, suppose, Moliere screening angle refer to multiple scattering only
and the FANO-ON/OFF refers to corrections to the Poisson distribution of the

Since, obviously, I understood or implemented it wrongly (or, sadly, both)
I would kindly ask for some extra explanation on the MULSOPT options.


Health & Environment Department
Nano Systems

Received on Mon Nov 16 2009 - 15:18:53 CET

This archive was generated by hypermail 2.2.0 : Mon Nov 16 2009 - 15:18:55 CET