My first attempt at an efficiency measurement compares wire hits when you require that the first (wire 1) and last (wire 6) wires in a single super layer are hit.
First I looked at which wires were hit when I require that there is a hit on wire 1 and wire 2.
HV was G:F:S = 536:-750:1500 Volts
Most of the hits are in row 9.
If I histogram all wire hits requiring a hit in both wire 1, wire 6 and row 9 I see the following
Now I divide by the number of hits seen by both wire 1 and wire 6
If I now require that Wires 1-3 and 5-6 from column 9 have hits and then ask how many hits did wire 4 have I get an efficiency of about 98%.
Using run 3834, the efficiency increase to 99% when the discriminator is increased from -30 mV to -60 mV