I attach an example of using BTTracker to do the stepping. Please see comments for details on the code. I check

1. Tracking forwards and then backwards returns particle back to the origin.
2. Tracking forwards in G4 gives same answer as BTTracker.

• put this in your maus/bin/examples directory
• source env.sh
• cd ${MAUS_ROOT_DIR}/bin/examples/
• run tar -xzf example_stepper_cpp.tar.gz
• cd example_stepper_cpp
• make
• ./example_stepper

There is a sample log file which has my output in. Let me know if you have any problems. Enjoy!