Re: smallest thickness

Perhaps it is worth to add that when the multiple Coulomb scattering
and energy loss approach is not valid, FLUKA can be made to revert to
single scattering. (Command MULSOPT, see manual)
Even better, it is possible to force single scattering in all cases: MULSOPT
with SDUM=GLOBEMF or GLOBAL, WHAT(6) > 1000.
I think that with this feature, even micron thicknesses should be
acceptable, although as an extreme limit. Of course, CPU time can become
prohibitive if the electron energy is larger than a few tens of keV

Alberto

On Sun, 2 Aug 2009, G. Battistoni wrote:

> The answer is not easy and not univoque.
> 1) First of all the minimum thickness in a transport code like FLUKA is
> meaningful if there are enough atoms to make valid the use of multiple
> coulomb scattering approach and energy loss
> calculations. Therefore it depends on the medium, its atomic properties
> and the density.
> I am aware of successful FLUKA calculations with silicon detectors of
> thickness of the order of few tens of microns. I doubt that a gaseous
> medium of the same thickness (in space) would obtain the same success.
> 2) There is at least a second consideration: in a given geometry the
> minimum thickness that can be appreciated depends on its ratio with
> respect to the maximum size of the problem itself. In other words, the
> scale of the minimum size has to be such to be within the resolution
> given by the precision accuracy. Take into account that FLUKA makes use
> of double precision. In order to exploit it, you have to write the
> geometrical parameters using the maximum precision (see the manual)
> Hope that these concept can guide you...
> Giuseppe Battistoni
>
>
> Mr. Bhushankumar Jagnnath Patil. wrote:
>> Dear Fluka experts,
>> I am studding the scattering of electron beam by using various
>> materials as scatterer(cylindrical geometry). I have a question that
>> how smallest thickness of the material I can give? Is FLUKA consider
>> micron thickness or not?
>> Thanking you.
>>
>> Mr. Bhushankumar Jagnnath Patil.
>> Microtron Accelerator Lab.
>> Department of Physics,
>> University of Pune,
>> Ganeshkhind, Pune 411007
>> Ph. No. Off. 020-25692678 Ext. 421
>> Mob. 9823968377
>> Webpage http://physics.unipune.ernet.in/~bjp
>> Alternate e-mail amolbhushan_at_gmail.com
>>
>
>

-- 
Alberto Fasso`
SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025
Phone: (1 650) 926 4762   Fax: (1 650) 926 3569
fasso_at_slac.stanford.edu