I.Larin 08/11 2006 1

0 dN/d distribution for selected runsbeen used for cross section calculations

Following cuts were applied• cluster energy greater than 0.5GeV• Energy sum of two s greater than 3.5GeV• Crystal part of Hycal was used for this analysis• Hycal timing: tdif within 4ns or 8ns (optional)• Best “in tdif” (closest to 0ns) candidate

Overview of 0 dN/d distribution

then two invariant mass distribution (with energy constraint) has been produced for

each bin of (0 production angle)

I.Larin 08/11 2006 2

0 dN/d distribution for selected runs, PWO-onlyEach bin of the distribution is a result of mass distribution fit

I.Larin 08/11 2006 3

Two invariant mass plots with the double gaussian fit; dN/dfor bins for = 0…0.16 degrees

I.Larin 08/11 2006 4

Two invariant mass plots with the double gaussian fit; dN/d for bins for = 1.12…1.28 degrees

I.Larin 08/11 2006 5

Two invariant mass plots with the double gaussian fit; dN/d for bins for = 2.4…2.56 degrees

I.Larin 08/11 2006 6

Two invariant mass plot with the double gaussian fit; dN/d for all bins

I.Larin 08/11 2006 7

No systematic shift between number of signal events in the total distribution and sum of partial (dN/d) mass distributions within statistical error of ~1%

I.Larin 08/11 2006 8

0 invariant mass spectrum without and with energy constraint

Contribution of selected bands

I.Larin 08/11 2006 9

Elasticity distribution with 0 mass constraint for events with no Hycal trigger bit-9 presented and

for all events

I.Larin 08/11 2006 10

No artificial structure under the elasticity peak resulting from mass constraint method is seen

I.Larin 08/11 2006 11

0 tdif distributionEach bin of the distribution is a result of mass distribution fit

I.Larin 08/11 2006 12

Two g invariant mass plot with the double gaussian fit; dN/d for all bins

| tdif | < 8ns cut

Difference betweendistributions with| tdif | < 8ns and| tdif | < 4ns cuts

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Two plots for| tdif | < 8ns and | tdif | < 4ns cutsPrimakoff region is selected

0 dN/d distribution, comparing timing cuts

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Difference between two results obtained with 4ns and 8ns timing cut is 0.8%

which is also within statistical error level

I.Larin 08/11 2006 15

Studying tagging ratio fluctuations during the first snake scan

• First, events with Tagger hit in one of 11 production T-counters were selected

• Hycal scan periods close to edges or central hole were excluded from the analysis as well as beam trips

• Then Hycal energy deposition was required to distinguish “false” and “real” Tagger candidates

• Three sets of “enough energy” in Hycal were selected: 20%, 40% and 60% of nominal beam energy (given by Tagger)

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Hycal energy response: ratio of Hycal energy to Beam energy defined by Tagger

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Tagging ratio (integrated over all 11 T-counters) defined with 3 values of Hycal energy cut VS snake scan time

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Tagging ratio (integrated over all 11 T-counters) fluctuations during the first snake

One entry per one time interval

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Tagging ratio for 1 and 2 T-counters, fluctuations during the first snake

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Tagging ratio for all E-channels, defined with Hycal, integrated over all first snake time

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Tagging ratio fluctuations during the first snake scan period were within 0.9%

Since Hycal was used in this study some fluctuations may come from Hycal response function difference for different Hycal parts