Re: (Anti)Neutrino issues

From: Alberto Fasso' <fasso_at_slac.stanford.edu>
Date: Tue, 20 Aug 2013 07:12:37 -0700 (PDT)

Dear Ali Koosha,

I am not able to answer all your questions (hopefully some colleague will
do that), but I will try to clarify your points (1-b) and (4).

> (1-b) I think the folliwng argument in the user's manual has ambiguities.
> Please calrify what is saying by this:
> "Neutrino interactions however are implemented, but independently from
> tracking."

There is no ambiguity. You can track neutrinos, but only as non-interacting
particles. A neutrino can be followed through the geometry, you can score
boundary crossing and track length fluence, until the neutrino escapes into
the black hole. No interaction takes place. Or, you can force the neutrino to
interact with a nucleus at a point, but you will have no information about
how the neutrino got there. You cannot have both things at the same time.

> (4) ¿½BTit seems that the documentation about neutrino transport process in
> the Fluka jargon is rather poor. A direct search will result in nothing more
> than some papers of cosmic project of the Fluka team.

The documentation is poor because neutrino transport is a purely geometric
effect. It is similar to what a RAY does (or, if you are familiar with the
Geant code, to a Geantino). What is there to document? Just the intersection of
a straight line with surfaces of 1st or 2nd degree...
Neutrino nuclear interactions are another matter, but as said above they are
not connected with transport.

Alberto


On Mon, 19 Aug 2013, Ali Koosha wrote:

> Dear Fluka experts,
>
> I'm simulating neutrino interaction events using the Fluka code.
> I put a cylindrical scintillator in front of a mono-directional
> beam of electron anti-neutrino (ANEUTRIE). To make the run process
> be possible, I "undiscarded" the all 6 types of neutrino/antineutrino
> particles via the following card:
>
> DISCARD -neutrie -neutim -neutrit -aneutrie -aneutim -aneutrit
>
> The program runs well in most cases. However, there exists some
> misconceptions about what appears in the results:
>
> (1) The attenuation occures to antineutrinos seems to be "huge"
> compared to the cross sections we already know about its interactions
> (see Fig below). This is strictly in contrast to the "users manual"
> arguments
> that says that electron and muon (anti)neutrinos are produced and trackes
> without
> interactions. I just know that Fluka "forces" the (anti)neutrinos to
> interact near the BEAMPOS, but I little know about the consequences
> this might have in interpretation of results.
>
> (1-a) It seems that there is NO working (anti)neutrino production available
> in Fluka. For example occuring "Fission" reaction should result in
> (anti)neutrino
> secondaries, but I was not able to see anything.
>
> (1-b) I think the folliwng argument in the user's manual has ambiguities.
> Please calrify what is saying by this:
> "Neutrino interactions however are implemented, but independently from
> tracking."
>
> (2) Reducing the primary (ANTINEUTRIE) particles' energy to 0.1 GeV, the
> program crashes and "erroneously" reports that there exists to many
> "geometry"
> errors in the input file.
>
> (3) In addition to (2), setting the energy to higher values, but also
> setting the PART-THR of desired particles to values less than 0.1 GeV
> will result to the same erroneous "error"!
>
> (4) BTW it seems that the documentation about neutrino transport process in
> the Fluka jargon is rather poor. A direct search will result in nothing more
> than some papers of cosmic project of the Fluka team.
>
> Cheers,
> --
> Ali Koosha
Received on Wed Aug 21 2013 - 00:04:21 CEST