Created attachment 644 [details]
Macro, detector construction and output files to run with TestEm1

A detailed description is on the Geant4 forum here: https://geant4-forum.web.cern.ch/t/segmentation-fault-after-changing-material-of-a-volume-back-to-the-first-defined-material-for-this-volume/3267


A segmentation fault takes place when an object's material is changed, and then changed back to the original material.


The problem can be reproduced by using TestEm1 with the attached files:

After some time I tried to reproduce my problem using the TestEm1 example and finally I got it. But it is a mistery to me. I describe it below in four runs:

Description:

I used the version 10.06.p02 with your mac file: moralles.mac.txt
RESULT: OK, no errors.

I changed from emstandard_opt0 to emstandard_opt4.
RESULT: OK, no errors.

After this I have changed the SetMaterial method to reproduce the way I do it in my code:

I have commented
G4RunManager::GetRunManager()->PhysicsHasBeenModified();
and I have included
G4RunManager::GetRunManager()->ReinitializeGeometry();

So, the Construct() will be called again after material changes.

I used your mac file: moralles.mac.txt
RESULT: OK, no errors.

I changed from emstandard_opt0 to emstandard_opt4.
RESULT: SEGMENTAION FAULT when the material come back to G4_Al.

So, there is a combination to produce the error:
G4RunManager::GetRunManager()->ReinitializeGeometry();
with
emstandard_opt4
with
material change.

I hope someone can explain what what happens in this case.