From: Giuseppe Battistoni (Giuseppe.Battistoni@mi.infn.it)
Date: Fri Nov 03 2006 - 00:54:24 CET
Hi Joseph,
I am not sure of what you are talking exactly, but maybe there is a
misunderstanding that it could be important to clear for all those who
have access to the fluka-discuss list: double precision in
tracking and geometry has nothing to do with physics models and their
reliability.
The need of it is to avoid problems in complicated geometries, like thin
layers. A typical problem of GEANT-3, for instance, was the possibility of
missing a thin silicon layer in detector geometries of several meters
scale.
In the FLUKA approach, similar things must be avoided. Physics models
(energy losses, particle production etc.) may improve in the future
(hopefully). All the rest is just mathematics and has to be kept at the
maximum possible level of reliability.
Maybe your point was another one...
Cheers
Giuseppe Battistoni for the FLUKA collaboration
On Thu, 2 Nov 2006, Joseph Comfort wrote:
> Date: Thu, 02 Nov 2006 15:42:12 -0700
> From: Joseph Comfort <Joseph.Comfort@asu.edu>
> To: Francesco Cerutti <Francesco.Cerutti@cern.ch>
> Cc: fluka-discuss@fluka.org
> Subject: Re: Problem with source.f
>
> Hi Francesco,
>
> Thank you for the suggestion. It worked. And I have a better
> understanding of how to prepare geometries.
>
> On another topic, the message about double precision that was sent out
> by someone earlier rather irritated me, and I can't get over it. We
> need to keep in mind that the data upon which the models are being built
> are seldom (if ever) better than 1% or so, absolute. If a model can get
> within a few percent (3-4 significant digits) of good data, it is doing
> well. This is just a comment and I don't mean to get into arguments,
> nor to lose any friendships.
>
> Thank you,
> Joe
>
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