The data consists of:

event id:track id:track wt:x:y:z:px:py:pz:time  

position in cm, mom in gev/c time in seconds
track id 3 = pi+
track id 4 = pi-

Statistics:

Hg  4604 events   3.22 pi+/event   2.97 pi-/event

Cu  8840 events   2.19 pi+/event   1.93 pi-/event