[Gate-users] Strange pile up effects with Cylindrical PET system

[Simon Stute]

Hi,

On Fri, Feb 26, 2010 at 5:00 PM, K B <kd8had at gmail.com> wrote:

> Hello Simon,
>
>    I did check to make sure that the children are totally included in the
> mother volume ie. the thickness of the Rsector, module and cylindricalPET
> change accordingly to accommodate a 16 or 17 mm crystal. For all the various
> crystal thickness, I run a geometry check using
>  /geometry/test/recursive_test  and get :
>
>           GeomTest: no daughter volume extending outside mother detected.
>           GeomTest: no overlapping daughters detected.
>

OK, it was just to see if at least geometry was fine.
But I can't help you more now ! sorry ...

Good luck,
Simon



>
> Attached is another plot showing the total number of singles with energy
> greater than a certain value. On the yaxis I plot the total number of
> singles (normalized individually to 1 in each case) above a certain energy
> value (plotted on the y axis). The same plot is here as well :
> http://img7.imageshack.us/img7/1014/intgml.png. It is unusual to see that
> there are no tails past the 511 peak in the 17 mm case.
>
>
> KB
>
>
> >Hi,
> >
> >I have not really an idea to explain this physically speaking. But maybe
> >some suggestions about your simulation design.
> >Do your crystals are totally included in their mother volume ? I mean when
> >you make them grow to 17 mm, did you anticipate the size of the mother
> >volume.
> >In case of a child volume bigger than its mother volume, results are not
> >predictable at all !
> >Same thing when volumes are overlapping.
> >So maybe it comes from that.
> >
> >Cheers,
> >Simon
>