Re: Problem with REC body

Dear Joseph,

It could be easier to define a REC aligned with an axis and use
transformations, e.g.

$start_transform
..
$end_transform

to let FLUKA rotate it and take care of the accuracy. You will find
examples in the advanced course material on the FLUKA Web-site.

It is difficult to comment on the physics. If you would like us to have a
closed look, please post all necessary files (input, user routines etc)and
indicate which detector now gives different results.

Cheers
Stefan

On Sat, 7 May 2011, Joseph Comfort wrote:

> I have some more information with regards to the REC bodies.
>
> I did a side calculation and expanded the Height and 2nd Semiaxis values
> to 14 significant digits (with IDBG=0 still). The full geometry of my
> case was then handled (including all of my ARBs, etc.) without problems,
> and the case ran without glitches. Only the REC cards needed to be
> modified.
>
> The pipe for the second pair of RECs in the test file is actually
> circular, so I replaced the two REC bodies with RCC cylinders. There
> were no significant changes (beyond the random number sequencing) in the
> results. (Good.)
>
>
> However, the final results have notable differences from those with the
> 2008.3 Fluka. I save beam profile data at various places along the
> beamline structure. There are no significant differences between the
> two Fluka versions at locations prior to the start of the Pipe1 vacuum
> pipe.
>
> But I begin to see real differences even before the end of Pipe1. (The
> collimated neutral beamline is entirely outside of Pipe1, but halos
> extend inside it.) At the end of the entire beamline in the
> calculations, the new Fluka has about 8% less yield than the old one.
> The yield within a circle of radius 5 cm is about twice as much less.
>
> It is not obvious to me which code version is giving the most reliable
> results. Was the REC coding modified? The extra sensitivity on
> perpendicularity suggests it was. But, then, was a bug introduced or
> was a bug fixed?
>
> Thank you,
> Joe Comfort
>
>
Received on Sun May 08 2011 - 20:10:29 CEST