This example is based on extended/electromagnetic/TestEm3 and demonstrates how to register specialized tracking managers for a particle or a set of particles.

Geometry definition

The geometry of a simplified sampling calorimeter is used as in TestEm3 , please refer to its documentation for more details. The same UI commands exist for modifying the geometry (number of layers and absorbers, material and its thickness), without the /testem/ prefix.

In addition to the definition of the volumes, this example adds two regions, "Front" and "Back", which contain the front and rear half of the calorimeter.

Physics lists

By default, the example uses G4EmStandardPhysics and registers processes to the G4ProcessManager. This can be changed with the /setMode UI command. Possible values are:

processes: use G4EmStandardPhysics, the default
tracking: use the same physics as G4EmStandardPhysics, but implemented as a specialized tracking manager for electrons, positrons, and gammas; see the file EmStandardPhysicsTrackingManager.cc for details.
specialized: use a specialized tracking manager for gammas; for the purpose of demonstration,
- it uses G4EmStandardPhysics as the basis,
- defers processing of gammas with a kinetic energy of more than 100 MeV,
- implement a specialized stepping loop for the "Back" region of the detector. See the file SpecializedTrackingManager.cc for more details on the exact implementation.

How to start?

This example comes with one macro file for each of the described modes that can be passed as a parameter to the executable:

% exampleRE07 processes.mac
% exampleRE07 specialized.mac
% exampleRE07 tracking.mac