Implementation of Tower Isolation Cut

Originally posted 11 October 2005

Previously we had calibrated the BEMC using data from all triggers. We now have enough data to restrict ourselves to minimum-bias triggers. Additionally, we have implemented a cut that requires the pedestal-subtracted ADC value of neighboring towers to be less than twice the width of the pedestal. This cut does an excellent job of removing background, especially in the high-eta region:

The cut is used in the bottom plot. Unfortunately there is also a small subset of towers where the isolation cut breaks the calibration:

Again the cut is used in the bottom plot. We have decided to use the isolation cut when possible, and use the full minimum-bias data in the case of the (55) towers for which the cut breaks the calibration. This new calibration is able to recover ~30 towers that were previously too noisy to calibrate. We are in the process of reviewing the remaining bad towers found in 2005_MinBiasBadTowers.pdf. Towers 671,1612, and 4672 appear to have problems with stuck bits in the electronics, and there are a few other strange towers, but the majority of these towers just seem to have gains that are far too high. We plan on reviewing the HV settings for these towers. An ASCII file of the bad towers is attached below.