PrimEx Analysis Status

1
PrimEx Analysis Status

• Mark Ito
• November 19, 2005

• Accomplishments
• In progress
• Anomalies
• Next steps
• Bias

2
Accomplishments

• tri-modal LMS data
• Luminosity pass
• absolute/relative tagging ratio analysis
• pflux system
• tagger energy correction
• new tagger TDC data
• HyCal sum timing/accidentals

3
Tri-modal LMS correction
4
Absolute Tagging Ratio
5
Relative Tagging Ratios
6
Tagger Energy Correction
7
Tagger HYCAL time difference (ns)for 50 runs
(first file)
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Tagger HYCAL time difference (ns)Run 5003
(first 2 files)
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Accomplishments II

• Monte Carlo improvements
• TAC analysis multiple electron problem
• veto effect on pi0 yield
• new tagger calibration scheme
• understanding of trigger information
• sparsification linearity correction
• new HyCal snake calibration

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Monte Carlo Improvements
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Veto effect on p0 yield
12
Sparsification Energy Correction
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Accomplishments III

• HyCal gain stability confirmation
• Resolution vs. energy
• Position determination
• Other items...

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Long-term Gain Stability
15
Energy Resolution in PbWO4 Crystal Detectors
15
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Position Reconstruction in Transition Region
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In Progress

• Absolute/Relative tagging ratios
• offline monitoring
• z position determination
• beam position determination
• alternative clustering algorithm
• Finish clustering

18
In Progress 2

• physics analyses
• p0 Production Dustin
• Compton Yelena, Kelly
• Pair Production

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Anomalies

• global HyCal energy calibration
• gain vs. T-counter anomaly
• angle effect in coordinate reconstruction

20
Global Energy Calibration Anomaly
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gain vs. T-counter anomaly
22
angle effect in coordinate reconstruction
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Next Steps

• Get the lifetime (very preliminary, say 5)
• Settle on an yield analysis strategy or two
• Finish flux method
• Get a handle on acceptance and efficiency
• Scheme for getting lifetime from differential
  cross section
• Demonstrate lack of show stoppers
• There is a caveat...

24
Bias, Causes

• Once preliminary answer known, subsequent work
  can be biased
• Look for correction that go the right way
• Stop looking when answer is right.

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Bias, Remedies

• Secret fudge factor
• Introduced into pizero analysis
• Value revealed just before publication
• Do Compton first
• Set procedures on well-known cross section
• Agree not to change them for pizero
• Problems
• cross section not that well-known???
• reactions have different analyses
• agreement not to change hard to keep

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Summary

• We have a much better understanding of the
  detector
• Important task yet to be completed or started
• Need to think about overall analysis strategy