Two of the MWPCs were mounted on the hinged lid that formed the top of the dark box. The third MWPC was mounted below the dark box. One of the upper wire chambers did not function properly at the time this data were taken. The remaining two, however, functioned properly, which was sufficient for making the desired measurements.
The wire chambers were delayed signal type, meaning the anode signal line had delays between each anode wire that were long relative to the length of the anode wires themselves. This allows the particular anode wire hit in an event to be determined by the time at which the signal came in. The cathode wires were separated into two alternating sets designated as "even" and "odd". The difference of the even and odd signals is used to indicate on which side of the anode wire the particle passed through. The sum of the even and odd signals indicates the signal size. The obvious benefit of this design is that MWPCs with an arbitrary number of wires can be read out using two TDC channels and two ADC (analog to digital converter) channels as opposed to a separate set of TDC and ADC channels for each wire.
Three plastic veto staves were placed inside the dark box such that they were aligned vertically on top of one another as shown in Figure 4.1. Each stave was read out
on both ends by photomultiplier tubes. The analysis of this data focused on extracting two values: the effective attenuation length of PV staves and the signal velocity along the stave for position resolution via timing.