Translation of mother volume causing overlapping

Geometry, Fields and Transportation
1

Hi, I have a mother volume shaped like a simple cube, within which I’ve defined a complex geometry composed of roughly 20 smaller volumes. Recently, I decided to customize the mother volume to precisely match the shape of my geometry. To achieve this, I employed a G4Sphere with a radius of 332 mm and a theta angle of 8 degrees. I performed a translation to position the mother volume on top of my geometry.

However, during this translation, I encountered visual artifacts where the geometry volumes appear to overlap with the mother volume in the visualization, even though there is no physical overlap in the underlying geometry.

2

Dear @mogola
The translation of your geometry and the use of G4Sphere with a theta angle of 8 degree migh have created some overlaps in the system.
Remember that the dauthers’ coordinates are defined ralatively to the mother position. For example, a cube of 2 cm dimension will overlap with the above mentioned sphere (50 cm) mother when located at the center only because of the 8 degree theta angle. A simplified view is below
image

3

Thanks for the reply!
However, when I created the sphere, I set both the inner and outer radii to avoid this overlap. I attempted to make it hollow.

4

Check your sphere settings, then. Is it possible that you set the inner radius based on the simple cube dimenions, rather than the diagonal distance along your wedge?

1 Like
5

Check the inner radius according to the box dimensions. I think something is definitely overlapping there. You may also share parts of the geometry for faster issue identification and resolution.

6

Here is the piece of code:

G4double pmtGlassThickness = 2.0mm;
G4double pmtGlassRadius = 53.0mm;
G4double pmtCylRadius = 40.15mm;
G4double pmtTubeRadius = 26.1mm;
G4double pmtCylHeight = 18.0mm;
G4double pmtConeHeight = 20.0mm;

///////////////////////////////Defining World Volume/////////////////////////////////
G4Sphere mainSolid = new G4Sphere(“mainSolid”,
339.9mm,
340.mm,
0.0deg, 360.0deg,
0.0, 8.02deg);

G4Tubs coneWorld = new G4Tubs(“coneSolid”,
46.9mm,
47*mm,
51.*mm,
0.*deg, 360.*deg);

G4UnionSolid *motherSolid = new G4UnionSolid(“motherSolid”,
coneWorld,
mainSolid,
0,
G4ThreeVector(0.,0.,-286.*mm));

////////////////////////////////////////////////////////////////////////////////////

G4LogicalVolume *logicWorld = new G4LogicalVolume(//solidWorld,
motherSolid,
Air1,
//Water,
“logicWorld”);

G4Cons *SolidCone = new G4Cons(“pmtCone”,
pmtTubeRadius-pmtGlassThickness,
pmtTubeRadius,
pmtCylRadius-pmtGlassThickness,
pmtCylRadius,
pmtConeHeight/2.*mm,
0.*deg, 360.*deg);

G4Tubs *tube = new G4Tubs(“tube”,
pmtCylRadius-pmtGlassThickness,
pmtCylRadius,
pmtCylHeight/2.*mm,
0.*deg, 360.*deg);
G4UnionSolid combineSolid1 = new G4UnionSolid(“tubeplusreflection”,
SolidCone,
tube,
0,
G4ThreeVector(0.,0.,19.0mm));

G4LogicalVolume *logicCombine1 = new G4LogicalVolume(combineSolid1,
PMTGlass,
“logicCombine1”);

G4VPhysicalVolume *glassTube = new G4PVPlacement(0,
G4ThreeVector(0.,0.,0.),
logicCombine1,
“glassTube”,
logicWorld,
false,
0,
true);

G4Box *solidCutOff = new G4Box(“cutOffTubs”,
pmtGlassRadius+1.*cm,
pmtGlassRadius+1.cm,
34.597mm);

G4Sphere pmtGlassSolid = new G4Sphere(“pmtglass”,
pmtGlassRadius-pmtGlassThickness,
pmtGlassRadius,
0.0deg, 360.0deg,
0.0, 90deg);

G4SubtractionSolid pmtBulb = new G4SubtractionSolid(“pmtInnerglass”,
pmtGlassSolid,
solidCutOff);
G4Transform3D transform(G4Translate3D(0.0, 0.0, -17.702mm));

pmtGlassLogic = new G4LogicalVolume(pmtBulb,
PMTGlass,
“pmtGlassLogic”);

G4VPhysicalVolume pmtSphere = new G4PVPlacement(0,
//G4ThreeVector(0.,0.,-18.097mm),
G4ThreeVector(0.,0.,-6.597*mm),
pmtGlassLogic,
“pmtSphere”,
logicWorld,
false,
0,
true);