PrimEx p 0 radiative width extraction

1. PrimEx p0 radiative width extraction Eric Clinton University of Massachusetts Amherst June 21, 2007

2. Outline • Data Source and cuts • Event selection • Hybrid Mass Signal enhancement • Yields • Systematic effects from yield extraction • Simulation • Results • Sytematic Error Analysis

3. mysql -h primexdb -u primex_user book_keeping -b --execute="select run from run_list where radiator='A' and target='carbon' and type='pi0' and production='good';" > run_list.example mysql -h primexdb -u primex_user book_keeping -b --execute="select run from run_list where radiator='B' and target='carbon' and type='pi0' and production='good';" > run_list.example 1.) Two or more clusters/event. 2.) Minimum three (3) (PbWO4 or lead glass) detectors to define a “cluster”. 3.) 50 MeV or greater central (PbWO4 or lead glass) crystal detector energy in cluster. 4.) 10 MeV or greater minimum deposited energy in (PbWO4 or lead glass) detector. 5.) Max cluster energy 8 GeV. 6.) gg invariant mass greater than 0.085 GeV in at least one of the cluster pairs. 7.) Elasticity (cluster pair energy sum/tagger energy) greater than 0.70. 8.) Cluster energy greater than 0.5 GeV. 9.) Cluster X or Y position must be greater than 3.8 cm. 10.) Cluster pair energy sum between 3.5 and 6.5 GeV -- additional software cut not imposed on the skim, but imposed later: 11.) Timing cut of -15 ns to +5ns. “pi0gains” used as caliubration Data Source and Cuts

4. Likelihood Event entries have invariant mass, elasticity, and timing Which entry to choose in a mutli-entry event? Which is "most likely"? Fit invariant mass, elasticity, timing signal and background Fitted signal lineshape as probability density function (PDF) Evaluate the PDF for each parameter for each entry. Three individual likelihoods. PDFInvariant mass, PDFElasticity, PDFTiming Total likelihood = PDFInvariant mass × PDFElasticity ×PDFTiming Entry with highest total likelihood "wins". Event selectionEliminate Tagger and HyCal combinatorics

5. Most Likely invariant mass spectrum Final Likelihood PDFInvariant mass × PDFElasticity ×PDFTiming Getting Final Likelihood spectrumTake entire “Most Likely” spectrum as event sample

6. Misidentification – any systematics?No. MisID is random, and event selection tends to pick smaller production angle pions.

7. Original 2-D data Elasticity vs.Invariant Mass New 1-D signal AKA “Hybrid Mass” Rotation of 2-D data onto 1-DTry to enhance signal to noise

8. Selected Hybrid Mass Fits

9. p0 yields as a function of production angle.

10. Extracted yields over the entire pion angle range must be stable as these parameters are varied. Systematic error sources?

11. Lineshape Degrees of Freedomentire HyCal acceptance

12. Integration/BG subtraction rangeentire HyCal acceptance

13. Stability of Fit Rangeentire HyCal acceptance

14. The Veto—how it changes the angular spectrums

15. Extracting a Photon Misidentification EfficiencyPME = 0.76%

16. Simulation Work • Thrown with E-Channel Photon flux weighting • Primakoff (with FSI), Coherent (Cornell with FSI), Incoherent (Glauber) • Energy correction added • Energy lost out back of HyCal, out of cluster mask • Added back about 10% of energy • Tracking threshold tuned • Proper shower development • Resolution and centroid tuned • Get invariant mass right to proper mock physics • Vet the Simulation • Push 4 vectors from experiment thru sim • See how p0 candidate spectrum look, look for losses • Turn off detectors, see how acceptance behaves

17. Photon flux

18. Poor Elasticity

19. Energy CorrectionAcross entire HyCal acceptance

20. Tracking Threshold, resolution, and centroid tuning

21. Putting physics events thru the Simulation Around 99.2% fidelity

22. Turning off glass detectorsEntire HyCal Acceptance

23. Turning off tungstate detectorsEntire HyCal Acceptance

24. Turning off glass detectorsHyCal Tungstate Acceptance Only

25. Efficienciesas a function of the photo-pion process, entire HyCal acceptance

26. Geometric efficiency and reconstruction (cut) efficiency.Entire HyCal Acceptance

27. Efficienciesas a function of the photo-pion process, HyCal Tungstate acceptance

28. Geometric efficiency and reconstruction (cut) efficiency HyCal tungstate acceptance

29. Fit to Data, and Extracted WidthEntire HyCal Acceptance Extracted width – 7.870 eV ± 0.139 eV (1.77%)

30. Fit to Data, and Extracted WidthHyCal Tungstate AcceptanceExtracted width – 7.859 eV ± 0.146 eV (1.86%)

31. Acceptance Corrected Cross Sections Entire HyCal Acceptance PRELIMINARY HyCal Tungstate Acceptance

32. Systematic Error Entire HyCal acceptance • Nominal 7.870 NA • Veto width: 7.779 -1.16 • Cluster Position Finding Method • Method 0: 7.720 -1.90 • Method 1: 7.888 0.23 * (+) • Method 2: 7.938 0.86 • Method 4: 7.849 -0.27 • Lineshape (degrees of freedom)*** • DG3Sp: 7.859 -0.14 * (-) • TG3Po: 7.931 0.77 * (+) • Integration range (Nominal cutoff = 1.0%) • 3% width: 7.802 -0.86 * (-) • 2% width: 7.841 -0.36 • 0.5% width: 7.966 1.22 • 0.3% width: 7.966 1.22 *(+) • 0.2% width: 8.001 1.67 • Fit Range (nominal = ±0.030 HMU’s • -27, +27 7.760 -1.40 % • -33, +33 7.973 1.31 % • Average = 7.867 -0.03 % *(-) • -30, +33 7.838 -0.41 % • -30, +27 7.877 0.09 % • Average = 7.862 -0.10 % *(-) • -27,+30 7.745 -1.58 % • -33, +30 8.002 1.68 % • Average 7.870 0.04 % (+) • Adding the *(+) gives positive sytematic shift +1.46 • Adding the *(-) gives negative systematic shift -0.88 • Systematic Error = +1.46, -0.88 ***Nominal = Double gaussians with 3rd order polynominal DG3Sp = Double gaussians with 3rd order spline TG3Po = Triple gaussians with 3rd order polynominal

33. Systematic Error HyCal Tungstate acceptance • Nominal 7.859 NA • Veto width: 7.774 -1.16 • Cluster Position Finding Method • Method 0: 7.699 -2.04 • Method 1: 7.827 -0.41 * (-) • Method 2: 7.881 0.24 • Method 4: 7.670 -2.40 • Lineshape (degrees of freedom)*** • DG3Sp: 7.859 -0.00 * (-) • TG3Po: 7.891 0.41 * (+) • Integration range (Nominal cutoff = 1.0%) • 5% width: 7.788 -0.90 * (-) • 2% width: 7.813 -0.59 • 0.5% width: 7.877 0.22 • 0.2% width: 7.938 1.00 *(+) • 0.1% width: 7.926 1.31 • Fit Range (nominal = ±0.030 HMU’s • -27, +27 7.809 -0.63 % • -33, +33 7.888 0.36 % • Average = 7.867 -0.1 % *(-) • -30, +33 7.824 -0.45 % • -30, +27 7.888 0.36 % • Average = 7.862 -0.03 % *(-) • -27,+30 7.777 -1.04 % • -33, +30 7.941 1.04 % • Average 7.870 0.00 % (+) • Adding the *(+) gives positive sytematic shift +1.08 • Adding the *(-) gives negative systematic shift -0.99 • Systematic Error = +1.08, -0.99 ***Nominal = Double gaussians with 3rd order polynominal DG3Sp = Double gaussians with 3rd order spline TG3Po = Triple gaussians with 3rd order polynominal

34. Entire HyCal Acceptance Statistical Veto Off ± 1.77 Veto On ± 1.62 Photon Flux ±1.10 Systematic (Yield Extrn.) +1.46, -0.88 Branching Ratio ± 0.03 Target Thickness ± 0.04 Veto (if used) ± 0.05 HyCal Tungstate Acceptance Statistical Veto Off ± 1.86 Veto On ± 1.75 Photon Flux ±1.10 Systematic (Yield Extrn.) +1.08, -0.99 Branching Ratio ±0.03 Target Thickness ±0.04 Veto (if used) ± 0.05 Total Error budget

35. Entire HyCal Acceptance Gp0→gg = 7.870 eV ± 0.139 eV +0.144 eV – 0.111 eV Gp0→gg = 7.870 eV ± 1.77 % +1.83% - 1.41% HyCal Tungstate Acceptance Gp0→gg = 7.859 eV ± 0.146 eV +0.121 eV – 0.116 eV Gp0→gg = 7.859 eV ± 1.86 % +1.54% - 1.48% Result

36. Future work • Work another nuclear incoherent generator • Evolve cross sections to the weighted mean photon energy • Lead Target Data?