1. Physics Lists Design

2. Design choices, my personal opinion
Readability
Maintainability
try a new option in a new PL variant
Model
Cross section
Consistency checks
Have all physics, no duplicates
Performance less important

3. G4VModularPhysicsList
Physics list needs to implement
using
public: // with description
// This method will be invoked in the Construct() method.
// each particle type will be instantiated
virtual void ConstructParticle();
// each physics process will be instantiated and
// registered to the process manager of each particle type
virtual void ConstructProcess();
void RegisterPhysics(G4VPhysicsConstructor* );
// Replace Physics Constructor
// The existing physics constructor with same physics_type as one of
// the given physics constructor is replaced
// (existing physics will be deleted)
// If any corresponding physics constructor is found,
// the given physics constructor is just added
void ReplacePhysics(G4VPhysicsConstructor* );

4. Hierarchy in constrcuting
Physics list
Example FTFP_BERT
Checks user environment for needed data
Constructs physics using
 Physics Constructors
HadronPhysicsFTFP_BERT, G4EmStandardPhysics, ….
 Physics Builders
now only for hadron inelastic

5. An example: HadronPhysicsFTFP_BERT
ConstructProcess:
G4NeutronBuilder has processes for Neutron
CreateModels() registers (G4VNeutronBuilder) ‘models’ to G4NeutronBuilder
G4FTFPNeutronBuilder
G4BertiniNeutronBuilder
G4LEPNeutronBuilder ( using capture & fission)
G4NeutronBuilder::Build() calls Build() for all ‘models’ and physics (elastic,inelastic, capture, fission) and then registers the process with the particle
G4LEPNeutronBuilder::Build(G4Hadron”physics” Process)
HadronPhysicsFTFP_BERT(G4int verbose =1);
HadronPhysicsFTFP_BERT(const G4String& name,
G4bool quasiElastic=false);
virtual ~HadronPhysicsFTFP_BERT();
public:
virtual void ConstructParticle();
virtual void ConstructProcess();
private:
void CreateModels();
CreateModels();
(G4NeutronBuilder*) theNeutrons->Build();
thePro->Build(); …
//may add cross section data sets

6. Strong & weak points Is strongly typed
strong typing in part forces to repeat similar code
Some checks on completeness of a physics list
Keeps types of physics in one class per particle
Forces to implement all physics components
This contributes to code repetition as well.
Cross sections not handled consistently
Cross section added in builder for a model
Could be or partially is done in Physics Constructor
But HP cross sections are model cross sections, valid over the energy of the model