Ability to define thresholds in energy

From requirements session @ Rennes CM

ALICE

Problem:

• Double conversion Energy => Range => Energy is redundant
• Geant4 provides only RangeToEnergy converters but not EnergyToRange, so we have to perform time consuming extrapolations to get the resulting energy match with the original one
• The conversion takes 75% of the total initialization time
• The final energy threshold does not match exactly the initial value due to the approximations 

Suggestions:

• Either have a method per region & material to set the cuts in energy
• Or have a possibility to predefine G4ProductionCutsTable with the energy thresholds that would not be then recomputed
• Or, if none of the above can be done, provide a fast EnergyToRange converter that could replace our own computations

Contacts:

• Ivana Hrivnacova: ivana.hrivnacova@cern.ch
• Sandro Wenzel: sandro.wenzel@cern.ch