Here I compare the endcap gains currently in the DB to the new gains calculated by Shirvel ...

The endcap tower gains used in the initial production of the 2009 jet trees were the 2006 gains modified to take into account the HV changes made at the end of Run 7. Measurements of the Pion mass in the endcap using these gains seemed to show that the gains were too large and comparisons of simulated jets in the endcap were consistent with that picture.

We did not have a tower-by-tower MIP calibration in place in time for the jet embedding simulations to begin, so we decided to uniformily lower the gains present in the database by 7.5% which was roughly the discrepency seen in the Pion mass measurements.

Figure 1: This figure shows the data (Blue) / simulation (Red) jet eta spectra comparisons using the old gains (top pannel) and the gains lowered by 7.5% (bottom pannel).

As can be seen in figure 1, the new gains vastly improved the data / simulation agreement in the endcap region although there is still slight disagreement at the highest etas. Shirvel has been working on a tower by tower MIP calibration and I wanted to see if there were any systematic differences between the gains obtained by lowering the DB gains by 7.5% and the gains obtained by Shirvel. The 7.5% drop gains get the eta spectrum about right, but it would be good to make sure there are aren't large gain shifts at some eta values and smaller gain shifts at others. Also, I would naively expect the "correct" gains to be a little lower at large etas to make up for the slight simulation excess above data seen in the above plot.

The endcap has 720 towers (index[0,719]) arranged into 12 sectors in phi,each containing 5 subsectors in phi with each subsector containing 12 eta bins (12X5X12 = 720). Each tower has a name which denotes its sector, subsector, and eta bin, ie tower 02TB05 is in sector 2, subsector B and eta bin 5. The index numbers map to the tower names as:

Index:     Tower Name:

00           01TA01

01           01TA02

02           01TA03

...           ...

12           01TB01

...           ...

The physical location of each index in x-y space as well as the phi and eta bin which corresponds to each index is shown in figure 2 below (there may be an inversion about the Y axis.

Figure 2: The location of the tower with a given index in X-Y space (top figure) and phi-bin vs eta-bin space (bottom figure).

As a cross check, I show the difference between the original Run 9 gains which were taken from the 2006 HV corrected gains and the gains which were lowered by 7.5%.

Figure 3: This figure shows the percent change in the gains between the original Run 9 gains and the lowered Run 9 gains. All values should be very close to 7.5%.

Figure 4: This figure shows the ratio of the gains Shirvel calculated over the gains currently in the DB (the 7.5% lowered gains) for each phi and eta bin.

Patterns are hard to see in the above plot, so I have made a series of 1-D plots showing the gain ratio for each phi bin for the 12 different eta bins. I also show a line which denotes the average of all bins that are non-zero.

Figure 5: Here are the gain ratios vs phi for the 12 eta bins. Remember that eta bin 0 is closest to eta=2 and eta bin 11 is closest to eta=1.