Hi, all.
I am simulating an RPC-PET scanner, which consists of a hollow box placed in the center of the world volume (via a G4PVPlacement). Inside the hollow box, four detection heads are placed through a G4PVParameterised by means of a translation vector and rotation matrices defining 0, 90, 180, and 270 degrees rotations about the Z axes.
Each detection head consists of a solid box, inside of which another solid box is placed by means of a G4PVPlacement. In this inner box, a given number of similar detectors (defined by solid boxes), are placed through a G4PVParameterised by means of translation vectors.
Inside of each detector, two tight detection modules (defined by solid boxes), are placed through G4PVParameterised. Even modules are placed by means of translation vectors, and odd modules are placed by means of translation vectors and a 180 degree rotation matrix about the Z axis.
Inside each detection module, several layers (solid boxes) with different dimensions are placed through a G4PVParameterised by means of translation vectors.
With the exception of the world volume, all objects share the same sensitive detector.
The geometry is depicted in the attached file.
Geometry.pdf (95.5 KB)
When a particle goes from the scanner to the outer box of the detection head, or from the outer box of the detection head to the inner box of the detection head, or from the inner box of the detection head to the first layer of a detection module, the post step point is fGeomBoundary, and the pre and post step points have different IDs (replica/copy numbers) and volume names (as expected). Equally, if the first step is in the scanner, in the outer box of the detection head, or in the inner box of the detection head the volume IDs and names of the pre and post step points are correct.
However, inside the layers of the the RPCs (all layers that are inside the volume of the modules), when a particle crosses the boundary the pre and post IDs (replica/copy numbers) of the layers are different and correct, but the pre and post volume names are the same.
Any suggestion for this behavior?
Thanks in advance.