DNA physics in only one of multiple Regions

Hello,

I have several G4Regions in a geometry and want to activate the DNA physics in one of them. As an example I use the microdosimetry example. Here I have added another volume and region:

G4Box* testSolid = new G4Box("Test",worldSizeX/2, worldSizeY/2,TargetSizeZ/2);
G4LogicalVolume* logicTest = new G4LogicalVolume(testSolid, fpWaterMaterial,"Test");
new G4PVPlacement(0, G4ThreeVector(0,0,TargetSizeZ*2), "Test", logicTest, physiWorld, false, 0);

testRegion = new G4Region("Test");
testRegion->SetProductionCuts(cuts);
testRegion->AddRootLogicalVolume(logicTest); 

If I now run the example, I would expect the DNA processes to be active in the target region, but the standard processes to be active in the test region, since the DNA models were only assigned to the target region. However, I only observe the DNA processes in the test region and no standard process. The same happens when I use the G4EmDNAPhysicsActivator instead of the PhysicsList of the example.

G4VModularPhysicsList* physicsList = new G4VModularPhysicsList();
physicsList->RegisterPhysics( new G4EmLivermorePhysics() );
physicsList->RegisterPhysics(new G4EmDNAPhysicsActivator());
G4EmParameters* param = G4EmParameters::Instance();
param->AddDNA("Target", "DNA_Opt4");

What is the reason for this? How can the DNA models be deactivated in the test region?

Geant4 Version: 10.07

Background: I am actually simulating protons in a water phantom with a gold nanoparticle, using the DNA models for water in water and the DNA models for gold in gold for electrons and the Livermore processes for protons. The above example is just to demonstrate the problem.

1 Like

I am also struggling with a similar problem. Any solution?

Dear All, please could you refer to the next public release? The activation of different EM physics lists in different regions has been improved significantly.

Hi, thanks for the suggestion. I have tried with Geant4 11.0 and unfortunately it is exactly the same problem.

Thanks for report. We are working on this issue. For Geant4-DNA examples, we have also provided another example AuNP for nanoparticle applications. Can it can help some ?

Unfortunately no. They use DNA models for water in the default world region and for gold in the NP region. What we want to have is a region with DNA water processes, a region with DNA gold processes and standard Livermore processes in the default world region. And it seems like Geant4 can not assign the different processes to the two different regions.