Re: "Neutron" dose

Dear Thomas,

> I assume that Alberto's statement above means, that Neutron dose is
> kerma in the case that the secondary is not a proton, else the proton
> will "take care" about depositing the energy (via delta rays, low
> energy electros and so on, depending on the chosen PART-THR). Can you
> confirm or correct ?

In FLUKA, protons from neutron rections are explicitely transported in two
cases and only those two cases:
1) recoil protons, i.e. hydrogen nuclei hit by a neutron
2) protons from N(n,p) reaction
but protons from other (n,p), (n,np) etc. reactions are not transported
and their energy is deposited as kerma.
If you read again carefully Sec. 10.3.3 of the manual, you will realize
that this is exactly what the manual says.
In my previous mail, my intent was to stress the fact that in real life
energy is ultimately deposited by electrons, and I mentioned the kerma
approximation used by FLUKA for the majority of low-energy neutron reactions,
without thinking it necessary to refer to the two exceptions 1) and 2) above.

Best regards,

Alberto

On Tue, 8 Sep 2009, Thomas Otto wrote:

>
> Dear colleagues,
>
> I would like to thank Alberto Fass=F2 for his explanation that energy is
> finally imparted by electrons, in the archives under
> http://www.fluka.org/web_archive/earchive/new-fluka-discuss/2362.html .
>
> There is one statement which I need clarification about: Alberto writes
>
> " "Neutron dose" in FLUKA is kerma, which in the real world would
> be ionizing charged recoils, and they too would ionize by transferring
> energy to electrons."
>
> On the other hand, the manual states
> "10.3.3 Generation of charged particles [from l.E. neutrons]
> Recoil protons and protons from N(n,p) reaction are produced and
> transported explicitly, taking into account the detailed kinematics of
> elastic scattering, continuous energy loss with energy straggling, delta
> ray production, multiple and single scattering. [...] All other charged
> secondaries, including fission fragments, are not transported but their
> energy is deposited at the point of interaction (kerma approximation).
>
> I assume that Alberto's statement above means, that Neutron dose is
> kerma in the case that the secondary is not a proton, else the proton
> will "take care" about depositing the energy (via delta rays, low
> energy electros and so on, depending on the chosen PART-THR). Can you
> confirm or correct ?
> Thank you,
>
> Thomas
>
> Thomas OTTO
> Head, Dosimetry Service
> Radiation Protection Accelerators Meyrin
>
> DG-SCR
> CERN
> 1211 Gen=E8ve 23
> Switzerland
>
>

-- 
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