Eric's Preliminary Results from August 2002 Beam Test Data

TAC vs Tagger analysis

I regret to say that we have minimal if any useful TAC ADC information. Out of all of the TAC runs (769,770,771,772,773,774,775,776,797) only 771 has some correlated data.

Out of nearly 500,000 events, only about 550 events were valid TAC events. However, many of the TAC runs contain timing information. That analysis is ongoing.

Trigger 3 is the pre-scaled TAC trigger, and trigger 4 is the Master OR.

Tac VS Tagger on Trigger 3

Tac VS Tagger on Trigger 4

Tac VS Tagger on Trigger 4, rejecting events +- 700 from a y-intercept of 100

Tac VS Tagger on Trigger 4, rejecting events +- 900 from a y-intercept of 100

And here is the Profile of the 2-D histogram, and ROOT's best fit line. As you can see, we are severely handicapped by limited statistics. In this graph, the y-intercept should correspond to the TAC pedestal. A pedestal in the 3000's is somewhat absurd.

TAC vs Tagger profile on trig 3

An investigation into the data on the Master OR trigger looks a little more promising.

TAC vs Tagger profile on trig 4, y-inter = +-900

TAC Timing analysis

Here we can see definite correlation between the tagger and TAC TDC's.

TAGT vs TACT run 771, trig 3 & 4

TAGT vs TACT run 771, trig 3

TAGT vs TACT run 771, trig4

Veto Counter Analysis

We also encountered a few problems with the veto counters. It appears that only one Veto counter was eiter working or properly timed in with the Master OR. The VC we have data for is the longer one. It is also evident from the data that that the bottom channel is very noisy. There are a lot of spurious events in the bottom channel that have no correlation to either a hycal or top VC channel event. I have had partial though not complete success in removing the effects of this hot channel in software analysis.

Here we have the coincidences bewtween the top and bottom VC channels. Note that the center of the distribution appears to be off from zero. The only requirement for this histogram was a top/bottom coincidence. The following plots are from run 851, unless otherwise specified.

Veto Counter top/bottom coincidences without a Hycal cut

Veto Counter top/bottom coincidences with a HyCal cut

The next bit of analysis I will show is the VC timing differnce. Notice the assymetry on the positive side of the distribution. This is the result of the noisy bottom channel.

Veto Counter Timing difference without a Hycal Cut

Here I made a Hycal coincidence cut. All top/bottom coincidences not within a 500 ns window of a HYCAL event were rejected. This cleaned up quite a bit of the bottom channel noise.

Veto Counter Timing difference with a Hycal Cut

This last plot is the mean time for any coicidence signal to propagate through the VC. This time should reflect the total length of the VC, roughly 20 ns. However, we can still see a shoulder from the noisy bottom channel which widens out the time plate au from roughly 119 to 124 ns.

Veto Counter mean time with a Hycal Cut