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Analysis of the September data

A detailed analysis of September data collected; combining cycles, determining cut values, background subtraction, normalization, asymmetry calculations, and corrections for reliable results.

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Analysis of the September data

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  1. Analysis of the September data H. Kolanoski, K. Laihem, S. Riemann, A. Schälicke , DESY R. Dollan,T. Lohse , HU - Berlin R. Dollan, Princeton 22/05/06

  2. Collected data R. Dollan, Princeton 22/05/06

  3. What has to be done • Combine (reject) cycles • Determine values for later used cuts • Extract the signal -> subtract the Background • Cut • Normalize the data • Determine the Energydeposition in the CsI • Calculate Asymmetries • Normalize again • Correct • Compare results R. Dollan, Princeton 22/05/06

  4. General for this analysis Only superruns are included (Sept. (Oct.) data R. Dollan, Princeton 22/05/06

  5. General for this analysis Only superruns are included (Sept. (Oct.) data Only gain1 low sensitivity (12bit) data are used 15bit R. Dollan, Princeton 22/05/06

  6. General for this analysis Only superruns are included (Sept. (Oct.) data Only gain1 low sensitivity (12bit) data All data are normalized (Beamcurrent, Photonflux) R. Dollan, Princeton 22/05/06

  7. General for this analysis Only superruns are included (Sept. (Oct.) data Only gain1 low sensitivity (12bit) data All data are normalized (Beamcurrent, Photonflux) Only central crystal are used for the asymmetry calculation R. Dollan, Princeton 22/05/06

  8. + - + - Superruns R. Dollan, Princeton 22/05/06

  9. + - + - Pairing of superruns R. Dollan, Princeton 22/05/06

  10. Toroid 6130 • the histograms containe the signals of both cycles • mean value und width are used for further analysis stable example more unstable example R. Dollan, Princeton 22/05/06

  11. PcalE • the histograms containe the signals of both cycles • mean value und width are used for further analysis Background is changing over the two cycles „stable Background“ R. Dollan, Princeton 22/05/06

  12. The Cuts 3σ „Cut1“ „Cut2“ 1σ R. Dollan, Princeton 22/05/06

  13. The Signals in the CsI • Undulato on: Signal + Background • Undulator off : Background Bg How the Background has to be subtracted to get a stable result? Bg + signal We tested several Methods: R. Dollan, Princeton 22/05/06

  14. Normalization To the beamcurrent: • Each signal and background event is normalized to its corresponding toroid signal si , bj si / Ii , bj / Ij To the photonflux: • Each background subtracted signal is normalized to the readings of Ag1Sic ( si – bj)( si – bj)/ Φγ R. Dollan, Princeton 22/05/06

  15. Combining Signal and Background events Edep CsI Edep CsI Edep CsI Edep CsI time time time time N = Ns = Nb N = Ns = Nb or or or N = Ns + Nb N = Ns * Nb or „Meth.: D“ „Meth.: C1“ R. Dollan, Princeton 22/05/06

  16. BG subtr. Edep in the CsI crystals Sum of two Gaussians with the same meanvalue is fitted to the Energydistribution: Ffit = G1(μ,σ1) + G2(μ,σ2) = µ ns,nb - # of Signal/Background events in the fit FWHM - full width at half max. of the final fit R. Dollan, Princeton 22/05/06

  17. Asymmetries Ai Linear fit of Ai: S140(2nd) R. Dollan, Princeton 22/05/06

  18. Asymmetries Ai S140(2nd) Linear fit of Ai: define a figure of merit: R. Dollan, Princeton 22/05/06

  19. Asymmetries Ai S140(2nd) Ai weighted with Linear fit of Ai: define a figure of merit: R. Dollan, Princeton 22/05/06

  20. Asymmetries Ai S140(2nd) Ai weighted with Linear fit of Ai: define a figure of merit: R. Dollan, Princeton 22/05/06

  21. Conclusion • Combining every signal with every background event leads to the result with the smallest total uncertainty (Method D) R. Dollan, Princeton 22/05/06

  22. off on Correction Does the Undulator kick the beam when on ? Background changes for undulator on/off -> use Pcal to correct for it R. Dollan, Princeton 22/05/06

  23. off on Correction Does the Undulator kick the beam when on ? Background changes for undulator on/off -> use Pcal to correct for it R. Dollan, Princeton 22/05/06

  24. off on Correction Does the Undulator kick the beam when on ? Background changes for undulator on/off -> use Pcal to correct for it or R. Dollan, Princeton 22/05/06

  25. Beamcurrent normalization : Photonflux normalization : Corection event by event R. Dollan, Princeton 22/05/06

  26. E-166 Detector area (Top view) CsI SLAC Faraday Cup (removable) Under main CsI PosSi 2, 3 (mobile) C-2 Analyzer Bend C-1 g CsI G_cal-old Collimator Si SiC-old (mobile) e+ 15cm (reversible) magnetized Fe CsI DESY Collimator 2 Ag-2 Ag-1 Positron Spectrometer Analyzer Bend Ag1SiC g (5 MeV, 109), Etot ~ 0.5 104 TeV G_cal e- 0.4 X0, Ti Ag2SiC 15cm (reversible) magnetized Fe IP1 ~30 meters upstream Detector Segmentation DAQ ch. Description Location 1. Pcal B, C, D, E(e-) 1, 2, 3, 4 4x4 arrays, 23 layer: 1X0W/Si/G10, xyz sum above permanent dump magnets 2. Gcalold 1 8 12ch M1s, 23 layer: 1X0W/Si/G10, xyz sum mobile (background) 3. SiCold 1 9 12ch M1s, 15 layer: Si/G10, xyz sum mobile (background) 4. Ag2SiC 1 13 12ch. M1, 1 layer: 0.15X0W/G10/Si, xy sum inside Gcal box 5. Gcal Z1-4s 14-17 (s)ig:central 8ch M1s, Zsum| 1:1,2 2:3,4 3:5,6 4:7-9 Gcal box Z1-4b 18-21 (b)kgndl:corners 4ch M1s, Zsum| same as sig. 9 layers: 1X0W/G10/Si 6. PositronSi 1 22 12ch. M1, 1 layer Si/G10, xy sum between Faraday cup and e+ magnet (June05 run) 6a.PosSi 2 or 3 4-BL,TL,TR,BR 88,89,90,92 (1) 2x2 array, 1 layer: Si only in beam, between Faraday cup and e+ magnet (Sept05 run) 7. Ag1Si 1 23 12ch. M1, 1 layer 0.15X0W/G10/Si, xy sum upstream of Ag1 in Al box 8. Collimator Si 4-T,R,B,L 84,85,86,87 4-M1, 12ch arrays w/ 1X0W, 3mm hole aligned w/ collimator 3mm hole R. Dollan, Princeton 22/05/06

  27. Impact of correction and normalization • The normalization to the absolute photonflux is an additional improvement R. Dollan, Princeton 22/05/06

  28. Conlusions • Combining every signal with every background event leads to the result with the smallest total uncertainty (Method D) • The normalization to the absolute photonflux is an additional improvement R. Dollan, Princeton 22/05/06

  29. R. Dollan, Princeton 22/05/06

  30. The correction shifts the asymmetry within the errors R. Dollan, Princeton 22/05/06

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  32. Outlier rejection Criterion: Individual contribution to total χ2 Find next biggest χi -> remove whole superrun But R. Dollan, Princeton 22/05/06

  33. Conlusions - Asymmetry determination • Combining every signal with every background event leads to the result with the smallest total uncertainty (Method D) • The normalization to the absolute photonflux is an additional improvement • We should correct the data for steering effect • The outlier rejection is an additional method to improve the χ2/ ndf of the Asymmetry-Fit To do / questions • Compare results for selected runs with Tennessee • photon beam behavior in September ? • Run also over the june data (150A) with the selected methods • determine the asymmetries in the other crystals • estimate the final systematic uncertainty R. Dollan, Princeton 22/05/06

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  35. appendix R. Dollan, Princeton 22/05/06

  36. ) ( R. Dollan, Princeton 22/05/06

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