https://root.cern.ch/doc/v632/classTEveTrackPropagator.html
ROOT: TEveTrackPropagator Class Reference
rootclassreference
https://root.cern.ch/doc/v632/structTEveTrackPropagator_1_1Helix__t.html
ROOT: TEveTrackPropagator::Helix_t Struct Reference
roothelixstructreference