After examining the Z invariant mass peak calculated using the L2W data stream with the offline calibration applied, it seemed like there was a problem. The simplest explanation was that the relative gains were reversed, so that hypothesis was tested by examining the Z peak with the data reversed.

The slopes were also recalculated comparing the original histogram to histograms corrected with the relative gains and the inverse of the relative gains.

In the following two figures, black is the original value of the slopes, red has the relative gain applied, and blue has the inverse of the relative gain applied.

**Fig 1** Means of slope by eta ring with RMS

**Fig 2** RMS of slope by eta ring

The E/p calculation improves after making the change to the inverse of the relative slopes because the effect of outliers is reduced instead of amplified.

**Fig 3** E/p by eta ring with corrected relative gains

Update:

After last week's discussion at the EMC meeting, I recalculated all of the slopes and relative gains.

**Fig 4** Update Slope RMS calculation

I then used these relative gains to recalculate the absolute calibration. Jan used the calibration to rerun the Z analysis.

**Fig 5** Updated Z analysis

The updated calibration constants will now supercede the current calibration constatns.