Adding Neutralino Decays in Geant4

In 19.2.X.Y when GMSBIndex=1 was set then GMSB Neutralinos would be decayed
to a photon and a Gravitino within Geant4. This functionality was lost
during the configuration migration for MC16. This set of changes adds it back.
See ATLASSIM-3401.

Simulation/G4Extensions/Gauginos/python/GauginosConfig.py

@@ -24,3 +24,10 @@ def getGauginosPhysicsTool(name="GauginosPhysicsTool", **kwargs):
         ##kwargs.setdefault("GravitinoLifetime",    -1);
         ##kwargs.setdefault("GravitinoShortlived",  False);
     return CfgMgr.GauginosPhysicsTool(name, **kwargs)
+
+
+def getNeutralinoToPhotonPlusGravitino(name="NeutralinoToPhotonPlusGravitino", **kwargs):
+    kwargs.setdefault("ParticleName","s_chi_0_1")
+    kwargs.setdefault("BR", 1.0) # Branching Ratio
+    kwargs.setdefault("Daughters","s_G,gamma")
+    return CfgMgr.AddPhysicsDecayTool(name, kwargs)

Simulation/G4Extensions/Gauginos/python/GauginosConfigDb.py

@@ -2,3 +2,4 @@
 
 from AthenaCommon.CfgGetter import addTool
 addTool("Gauginos.GauginosConfig.getGauginosPhysicsTool"         , "GauginosPhysicsTool" )
+addTool("Gauginos.GauginosConfig.getNeutralinoToPhotonPlusGravitino", "NeutralinoToPhotonPlusGravitino")

Simulation/SimulationJobOptions/share/specialConfig/preInclude.GMSB.py

@@ -129,6 +129,7 @@ if doG4SimConfig:
     from G4AtlasApps.SimFlags import simFlags
     if GMSBIndex == 1: # generic neutralino to photon scenario
         simFlags.PhysicsOptions += ["GauginosPhysicsTool"]
+        simFlags.PhysicsOptions += ["NeutralinoToPhotonPlusGravitino"]
     elif GMSBIndex == 2 or GMSBIndex == 3 or GMSBIndex == 4: # generic stau scenario
         simFlags.PhysicsOptions += ["SleptonsPhysicsTool"]
     del GMSBIndex