There are three coordinate systems used:
Lab Coordinates - Hall coordinate system where y goes against gravity, z is in the direction of the beam, and x is to the left when looking down the beam
Target Coordinates - Origin at the center of the target. x goes with gravity, z is parallel to the ground in the direction towards the center of the
BigBite drift chambers or neutron arm
?. y is to the left looking down z
Detector Coordinates - Origin specified by center of the first
plane of the
drift chambers or neutron arm
?. x is "down" in the dispersion direction, z is in the nominal direction of particles such that z = 0 is defined by the first plane of the drift chamber for BB and the front of the shielding for thee neutron arm's N1. y is defined so we have a right handed coordinate system.