RE: Bug in FLUKA or error in the setup?

From: Alessio Mereghetti <Alessio.Mereghetti_at_cern.ch>
Date: Thu, 22 Aug 2013 12:16:51 +0000

2013 14:16:58 +0200 (CEST)
Sender: owner-fluka-discuss_at_smtp2.mi.infn.it

Hello FLUKA users and experts,

After a bit of time spent with Mina in checking the .inp file, we found a bug in the geometry, bringing the regions she was interested in to be of 0-volume. The bug was made subtle by the parametrisation of certain relevant dimensions of the geometry.

Parametrisation of the .inp file is a powerful and useful tool, especially when designing new devices etc... But, as Vasilis always recommends, use it carefully. In addition, a quick look at the most relevant settings in the .inp file (the one that actually run) with a text editor can be of help.

All the best!
A.

*********************************
Alessio Mereghetti
CERN, EN-STI-EET
Tel: +41 (0) 22 76 79564
Office: 864 2-D13
*********************************

________________________________________
From: Alessio Mereghetti
Sent: 15 August 2013 23:50
To: fluka-discuss_at_fluka.org
Subject: RE: Bug in FLUKA or error in the setup?

Hi Mina,

could you please attach also the .inp file and any other file you need to run it (eg user routines)?
I think it's really hard to disentangle a bug in the exe from an error in the .inp file with none of them :P
Cheers
Alessio

*********************************
Alessio Mereghetti
CERN, EN-STI-EET
Tel: +41 (0) 22 76 79564
Office: 864 2-D13
*********************************

________________________________________
From: owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it] on behalf of Mina Nozar [nozarm_at_triumf.ca]
Sent: 15 August 2013 21:19
To: fluka-discuss_at_fluka.org
Subject: Bug in FLUKA or error in the setup?

Hello everyone,

There is something happening in my setup that just doesn't make sense
and I have tried different things in the last three days, trying to find
out whether the mistake is from my part.

I have 75 MeV electron beam 4x4 cm square incident on a Beam Dump
composed of Al with some cooling channels. We have divided up the BD
and some of the shielding around the BD into sub regions in order to use
the results for thermal analysis.

Here is the description of the strange behaviour (as best as I can
describe it). The beam spot area (BS) where the beam hits is at an
angle of 3.06 deg. wrt the horizontal plane. The BS is 74 cm long, 4 mm
high, and 4 cm wide. I have the BS divided up into 16 equal regions:
BS1-BS16 (see attachment please).

When I look at the Beam Particle distribution (usrbin), I see the beam
go through all of these regions as expected but when I look at deposited
energy in BS4, BS8, BS12, and BS16 (stacked up vertically), I see zero
deposited energy. When I look at beam particle and photon fluences in
these regions, I see distributions that make sense but nothing in BS4,
BS8, BS12, and BS16. How could this be???

Another related oddity is that I see similar behaviour in the lead
shielding that lines up with these regions - longitudinally: PbSh1_6,
Pb_Sh1_14, PbSh1_22 (see attachment please). The only common thing
between these lead regions and the beam spot regions where I see no
deposited energy or beam particle/photons is that they share the same
two planes as the boundaries in x (longitudinally). I have not done
anything special with these regions - physics-wise, thresholds, etc. I
see both neutron and photon fluences (using usrbin) in these lead
regions and the adjacent regions show deposited energies but not
these... This does not make any sense.

EMF-cut is set to 100 keV for e+, e- and 10 keV for photons.


I would like to know whether this is a bug in FLUKA or some silly
mistake from my part (which I can't seem to find).

Thanks and best wishes,
Mina
Received on Fri Aug 23 2013 - 16:47:02 CEST