Strange Warning Message " Dump for solid"

[joaodfc]

Hello,

I am running a simulation consisting of several (non-overlapping) spheres inside a box, and I am scoring every ionisation inside a sphere. I’ve been running the simulations for a couple of proton energies, and between runs, I’ve been changing the seed using the function:

CLHEP::HepRandom::setTheSeed(seed);

Yesterday’s run went smoothly with no apparent problems, but in today’s simulations, for 250 keV protons, sometime after 10000 events, I got the warning message shown below.

I don’t really understand what the message means. And it happened at least one more time (the run hasn’t finished yet).
Can I still trust the results I will get from the run, or should I start a new run?

Any help is appreciated.

G4WT0 > --> Event 10000 starts with initial seeds (13022849,9845275).
G4WT2 >
G4WT2 > -----------------------------------------------------------

    *** Dump for solid - SVolume ***
    ===================================================
 Solid type: G4Sphere
 Parameters:
    inner radius: 0 mm
    outer radius: 1.7e-06 mm
    starting phi of segment  : 0 degrees
    delta phi of segment     : 360 degrees
    starting theta of segment: 0 degrees
    delta theta of segment   : 180 degrees
-----------------------------------------------------------

-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomSolids1002
      issued by : G4Sphere::DistanceToOut(p,v,..)
Undefined side for valid surface normal to solid.
Position:

p.x() = -1.050145407909561e-06 mm
p.y() = -7.898835272270622e-07 mm
p.z() = -1.079341811921444e-06 mm

Direction:

v.x() = -0.4254830210941504
v.y() = 0.7204651858913677
v.z() = 0.5476258893433654

Proposed distance :

snxt = 9e+99 mm

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------

[evc]

I would suggest that you replace G4Sphere with G4Orb, which is faster and more robust.

[joaodfc]

Hi @evc, thank you for your suggestion. I was unaware of that.

But regarding the warning message, should I be worried about the impact on the results?

[evc]

If this message appears rarely, then I would not worry.

I am not very familiar with G4Sphere code, but the warning message sounds for me like there was a problem with calculation of the normal to the surface in the point where the track leaves the sphere. It does not necessary mean that this will create a problem for the particle transportation.