Re: Material properties

By default, FLUKA calculates average ionization potentials in compounds
using the Bragg additivity rule. Of course, this does not take well
into account the effect of molecular bonds.

However, the user has the possibility to input his own values, if they
are available: see command MAT-PROP, WHAT(3).

Values of I (average ionization potential) for a number of compounds
can be found in ICRU Reports 37 and 49, and in an article of
Sternheimer, Berger and Seltzer, At. Data Nucl. Data Tab. 30, 261-271 (1984).
The values reported by the three documents are essentially the same.
You can find in them also some rules to derive corrections to I for
different kinds of molecular bonds and for different phases (gas/liquid or
solid).
See also:
J. Oddershede and J.R. Sabin, Nucl. Instr. Meth. B42, 7-10 (1984)

Best regards,

Alberto

On Sun, 5 Jul 2009, cocchi_at_cems.umn.edu wrote:

> Dear Fluka experts:
> I am a graduate student of Chemical Engineering, actually I
> am at he Chemical eng. dept. of the University of Minnesota
> and I am doing research on the Electron Beam induced
> polymerization of difunctional monomers. Actually we have an
> Electron beam apparatus built in the department labs and
> capable of delivering pulsed beams in the energy range 100 -
> 250 keV and we are doing research on reaction kinetics and
> network properties buildup.
> I started using FLUKA to model the energy deposition in the reaction
> chamber and to assess safety issues, although all the material of the
> chamber are present in the material database (copper, vacuum, nitrogen,
> lead, allumomium etc) the reaction media is not present. Actually my
> concern regards the effect of the insaturated carbon bonds, say the double
> bonds of the reacting monomer, and the prsence of double bounded oxygen in
> the molecules, infact I know from csda theory that correction should be
> applied for insaturatio, but I don't know how to do this in Fluka.
> It should be considered that the presence of double bounded oxygen and
> carbon can lead to partial delocalization of valence electron on the
> monomer molecules, this lead to different bonding energy. Can this be
> important? Actually the mechanism of initiation of Electron Beam
> polymerization is the excitation and ionization induced by the collision
> between incident electron and molecular electron.
> With my best regards
> Giovanni Cocchi
>
>

-- 
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