Two scintillators are placed on top and below the drift chamber
These scintillators have PMTs on both ends allow an initial position to be determined according to the time difference between the PMT hits.
Below is the calibration for Detector M and Detector G
HV(M1) = -1602 Volts HV(M2) = -1750 Volts
HV(G1)= -1700 Volts HV(G2)= -1650 Volts