Re: Energy deposition too low

... or otherwise, if the exp. data are normalized x incident flux, you
have to account for your simulated flux (which is 0.01 cm^-2) and divide
by it, getting again a factor 100

              Ciao
             Alfredo
On Thu, 27 Mar 2008, Francesco Cerutti wrote:

>
> Dear Joel,
>
>> I've made FLUKA runs using the suggested changes for 30 g/cm2
>> polyethylene, aluminum, and copper. The good part is that FLUKA
>> outputs the expected dose-depth behavior; the bad part is that the
>> energy deposition per unit ion is roughly two orders of magnitude
>> lower than experiment. Why do you think the energy deposition is
>> down?
>
> I guess that the point still lies in the crucial BEAM card.
> You are considering a beam with a uniform square spot (10cm side), i.e. a
> primary fluence of 0.01 cm-2. The energy deposition density (GeV cm-3) scored
> by USRBIN of course incorporates this factor (roughly speaking - assuming
> just ionization - it is equal to stopping power [-dE/dx] times primary
> fluence). This means that broad beams induce (obviously) low energy
> deposition density (i.e. - through the density factor - dose).
> If now what is measured, is the energy deposited over a transverse slice
> (GeV/cm as a function of z, longitudinal position i.e. depth), you should
> multiply the average energy deposition density over the slice by the slice
> area (this way in your case you get back two orders of magnitude)
>
> Hope this helps
>
> Francesco
>
> **************************************************
> Francesco Cerutti
> CERN-AB
> CH-1211 Geneva 23
> Switzerland
> tel. ++41 22 7678962
> fax ++41 22 7668854
>

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