You can assign a detector to a logical volume with the SetSensitveDetector method. With this method you pass a class that is called at every event inside this logical volume.

Inside this class you can distinguish the volumens by name and then collect whatever information you want.

I agree, G4VSensitiveDetector method is suitable.

- example in geant4/examples/extended/electromagnetic/TestEm10

I suggest you that use stepping action program, gather energy deposition in each volume and calculatedose simply.

SteppingAction is probably not a good choice. It can be complicated to find the volume you're in while you are in UserSteppingAction.

The G4SensitiveDetector is much easier to use since you get the name of the volume when the method ProcessHits in your detector class is called.

Actually collecting the energy is the the same, something like:

summedEnergyDeposit += aStep->GetTotalEnergyDeposit();

At first step it cannot link and compile the whole file HandsOn_5 in order to use the G4SensitiveDetector . I am using Virtual studio express.