These data were obtained in the cosmic ray test stand at VPI. The "Loose Trigger" is a three-fold coincidence trigger with large area scintillator planes which don't quite cover the superlayers in the z readout dimension but extend beyond the superlayer area in the phi dimension. There are some pickup strip channels in each plane which are not being readout due to a cabling error. One other strip is not showing hits due to unknown electronics problems. One channel is disabled because it always has hits. The end result is that the loose trigger data shows performance over almost all of the surface area, but with quoted efficiencies which are ~7% lower than the real efficiency because of the geometric acceptance and missing strips.
The "Tight trigger" has an additional scintillator 30cm x 40cm which limits the events to a smaller area.
The "Very Tight Trigger" has an even smaller scintillator 10cm x 15cm which insures that the events pass through all four superlayers in areas where the strips are all being readout. With this trigger we get efficiencies of 99+-0.5% for the superlayers.
This shows the acceptance of the loose trigger and the missing channels.
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Last Updated: 20 June 1996