1. Analysis Overview Kent Paschke HAPPEX Collaboration Meeting February 24, 2006

2. February 24 – April 21 SundayMondayTuesdayWedThursdayFridaySaturday 24 TODAY 25 26272812 3 Analysis I 4 56789 10 Analysis II 11 1213141516 17 Analysis III 18 1920212223 24 Analysis IV 25 2627282930 31 Analysis V 1 23456 7 Analysis VI COLLAB MEETING 8 COLLAB MEETING 9101112131415 161718 19JLAB Seminar? 202122 23 APS Talk 242526272829

3. Technical Notes Publications 2005 Hydrogen + Helium measurement – Letter Technical “Notes”Draft date Optics/Q 2 – Tim, Rob, Bob (Bryan, UMass) ? Finite acceptance – Bryan, David L., Kent ? Backgrounds – Ryan, Kent, Bryan, Bob ? Asymmetry analysis – Lisa, Rich, Hachemi, KK ? Polarimetry – David L., Paul S., Hachemi ? Transverse Asymmetry– Lisa, Kent ? Beam asymmetries Cavity performance

4. Raw Asymmetry Analysis Near-term: - epics words added to run.db files, re-run data, slug-pair and run-summary root files (Lisa) I - Inclusive RUNLIST check: review of runs in data set to verify runlist/run cuts. (Lisa) I Medium-term: Dither Quality Control (Syracuse) -I Review of averaged dither slopes, verifying consistency, avoiding outliers, etc. There have been almost NO quality checks for dither slope calculation/averaging. Averaging (Lisa and Syracuse) - II -modify run macro to avoid "binning" errors in averages - macros to average asymmetries by run, slug. - macros to average weighted pos difs and Aq. - pedestal error over run Pedestals/Linearity (Lisa) - III - Evaluate possible pedestal errors over run. - Verify pedestals at each current scan - Verify pedestals used for run periods. He Slugs 39-41. Fix these. (UMass) -II Exclusive RUNLIST check – Ryan Detector Weights (UMass) - II Density Fluctuations, detector correlations (UMass) -IV

5. Raw Asymmetry Analysis Longer-term: Beam Correction Quality (Umass) -V - Check systematics for large asymmetry runs - Characterize difference between regression and dithering - Estimate uncertainty in dithering/regression corrections. This is very important for helium. “Final” Data Set (Umass and Syracuse) - V - Make “Final” run root files with final cuts, pedestals, slope averages, pair and run sum. files - Verify pedestals, cuts, double differences, asymmetry corrections for final data set. - perform final averaging, with various summary tables similar to last year. - Evaluate asymmetry systematic error (pedestal, beam corrections, Aq correction). Tech Note! -V

6. Backgrounds Helium QE is almost done! Check stability over many measurements - I Rescattering: significant work remains -III Aluminum to be removed from rescattering probability –II Det pedestals for very low rates (if necessary) -II Correct rescattering for convolution with inelastic spectrum. -II Subtract radiative tail from inelastic spectrum - Requires simulation, but doesn’t need to be precise. (BRYAN) - II Aluminum: easy, but important cross checks must be done -III Verify on-line results, mainly trigger quality in counting and pedestals in integrating mode Verify observed Al dummy targets consistent with He/H cryo target spectra Reduced density target runs to verify “x T ” factor - V

7. Backgrounds Poletip: not yet started Propagate through field map to “measure” fraction of pole-tip intersections (Bob) - II Estimate possible number of near-tangent pole-tip intersections via SNAKE/gener_cone (Bryan, Kent) check sensitivity to details of collimation Tech Note!

8. Q2Q2Q2Q2 Much like last year, and much already done. Addendum note to last year’s tech-note is called for. Optics issues related to limited sieve collimator coverage? additional cross-checks of matrix elements vs. fp parameters... where does the matrix fail... or eliminate holes and re-fit optics db to check for errors. - I But NO CLEAR ERROR SIGNAL REMAINS... is there really anything here to worry about? Cross-check (Rob) - III Stability/Drift issues. (defer, but think about this) weight asymmetry average by (changing) Q 2 ? Was this stable during hydrogen (Bob, - II) Profile Scanner. Compare distribution parameters for drift over time Track Q 2 measurement vs. profile parameters over time Compare profile moments from scanner vs. spectrometer – Bob, on spectrometer: I. UMass, on scanner,: - II. Simulation, reproduce Q2 distribution?

9. Simulation gener_cone + SNAKE: Reproduce Q 2 distribution – (update in I) Radiative tail for subtraction in rescattering background calculation - II Average A NS over acceptance, radiative corrections (Tech Note) -V Average analyzing power over acceptance? (probably negligible) Estimate possible number of near-tangent pole-tip intersections via SNAKE/gener_cone (Bryan, Kent) - III check sensitivity to details of collimation MUCH additional work which may not be needed for unblinding: Improve match to magnetic transport, use optics db to reconstruct sieve pattern. Do we have comparable data without the septum (for future)? improve Multiple Scattering Match low density runs.... although what this takes isn’t clear

10. Polarimetery Electron Detector re-analysis straight-forward, but requires some labor? waiting for the photon analysis method to be refined, to spin both photon and electron analysis together We need David L to oversee this analysis Photon response function -> analyzing power. A better fit should reduce analyzing power systematic uncertainty. ~2 weeks before automated procedure for response function fit Compton co-incidence measurement? We need to have polarimetery top agenda at next meeting. How stable is the polarimetry analysis now? What is needed to finish it, at a minimal level? - I Mott results (vertical component most important) - II (for Helium syst) Moller results – smaller error bar? (how about vertical pol error bar?) Tech Note

11. Transverse Asymmetry Goal: to complete soon after unblinding. Verify background asymmetry ranges Verify pedestals, beam corrections. Use precision estimates from longitudinal runs for correction precision estimates Polarimetery: verify precision of Moller, come up with a defendable precision estimate WEEK IV L/R correction factor for He. (kent) Tech note...

12. 2005 - Physics Asymmetry Hydrogen Helium A PV :  ~ 0.21 ppm (3.5%) G E s :  ~ 0.014 2004: A PV :  ~ 0.84 ppm (11.2%) G E s :  ~ 0.042 A PV :  ~ 0.12 ppm (8%) G E s + 0.084 G M s :  ~ 0.012 2004: A PV :  ~ 0.24 ppm (17%) G E s + 0.080 G M s :  ~ 0.025 NOTE: Statistical error only! Systematic error will likely increase Helium error bar by <30%, and Hydrogen by <20%

13. Getting the story out – future talks JLab Seminar - April 21, 2006? First (JLab) release of 2005 results - APS @ Dallas - April 22-25, 2006 - April First public release of 2005 results - Paul Souder (session chaired by KK) PAVI @ Milos - May 16-20, 2006 HAPPEX 2005 results – David Armstrong Control of Beam Asymmetries- Kent P Transverse Asymmetry – Lisa K Q 2 and Backgrounds – Bryan M CIPANP @ Rio Mar - May30-June 3, 2006 HAPPEX 2005 results – Krishna Kumar

14. PREx Preparations Meeting Feb 25, 2006 A110, CEBAF Center 9:00 - 9:30 Paul Task List / Warm Septum 9:30 - 10:00 Bob New Electronics 10:00 - 10:30 David Compton Upgrade 10:30 - 11:00 KK Detector Design 11:00 - 11:30Eugene High-Field Moller 11:30 - 12:00 Discussion of other tasks