Re: convert MCNP geometry to FLUKA

From: Chris Theis <>
Date: Fri, 23 Dec 2011 13:33:46 +0100

Hello all,

automatic and full conversion between geometries of different MC codes is
in general difficult or rather impossible because it can only be performed
on the level of the smallest common denominator. Different codes have sometimes
different geometry philosophies (e.g. MARS or Geant) and even if they are
comparable their features are different (e.g. PHITS).

MCNP(X)->FLUKA will, at least for the moment, certainly not work without
manual intervention as FLUKA is missing features provided by MCNP's geometry
kernel. If the user has made use of them only a subset of the original geometry
can be converted at best. Among others one example is the torus which is not
supported in FLUKA. Also replicas or lattices work in a different way.

> for example in repeated geometries, and general quadratic
> surfaces: it simply crashes.

I'd appreciate if you could send me an example input to test because these
cases should normally be honoured with a warning instead of a crash. Which
version of SG did you use?

Regarding repeated geometries the philosophy of SimpleGeo is actually a bit
different which I would like to explain a bit in more detail. SG allows you
to create repeated geometries in a very simple way by putting your entity
(e.g. a fully modelled magnet) in a logical group and create with a mouse click
what we call a "replica". This is an identical copy which can be moved,
rotated etc. completely independent from it's source but internally a complete
geometric model is created and also exported. As a consequence region based scoring
or tallying can be directly applied without having to do extra programming
but using conventional input cards. In addition numerically sometimes problematic
bounding volumes as well as possible runtime penalties are avoided as well.
For those who are interested an example image of a full accelerator
beam line that was modelled with this can be found at:


On 23 Dec 2011, at 11:06, "Ali Koosha" <<>> wrote:

Hi All,
SimpleGeo is good for most simple geometries. However it has some
limitations, for example in repeated geometries, and general quadratic
surfaces: it simply crashes.
Note that the exported input file, needs extra effort to fit your request.

Ali Koosha
Received on Fri Dec 23 2011 - 14:00:03 CET

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