PrimEx Analysis Status Mark Ito November 19, 2005 ● Accomplishments ● In progress ● Anomalies ● Next steps ● Bias

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**

Tri-modal LMS correction

Absolute Tagging Ratio

Relative Tagging Ratios

Tagger Energy Correction

Tagger – HYCAL time difference (ns) for 50+ runs (first file)

Tagger – HYCAL time difference (ns) Run 5003 (first 2 files)

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

Monte Carlo Improvements

Veto effect on   yield

Sparsification Energy Correction

Accomplishments III ● HyCal gain stability confirmation* ● Resolution vs. energy* ● Position determination* ● Other items...

Long-term Gain Stability

15 Energy Resolution in PbWO 4 Crystal Detectors

16 Position Reconstruction in Transition Region

In Progress ● Absolute/Relative tagging ratios ● offline monitoring ● z position determination ● beam position determination ● alternative clustering algorithm ● Finish clustering

In Progress 2 ● physics analyses –   Production: Dustin – Compton: Yelena, Kelly – Pair Production:

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

Global Energy Calibration Anomaly

gain vs. T-counter anomaly

angle effect in coordinate reconstruction

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...

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.”

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

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