EMCal Recalibration Check Check of Debsankar’s and Dipali’s PWG Presentation on Kaon Mass Spectrum Fits PWG presentation on May 10 Determined the EMCal particle ID function parameters based on fits to mass spectra in each momentum bin Initial check of results shown last Monday at group meeting My mass width results are ~30% larger than those at the PWG (slide 9) Differences in two analyses Different background function choices Different mass fit regions for each momentum bin Use of PC3 tracking cut in my analysis (re-did my analysis without PC3 cuts) Results of checks of effects of differences done this week Background function difference does not lead to different fit widths PWG results are not stable with respect to size of mass fit region (slide 4) Not enough representative satellite channels for background PC3 tracking cut leads to better Signal/Background in kaon mass region We need to think about using this cut for the Run4 analysis Effects of PC3 cuts on S/B will be tabulated in a future spreadsheet but use of PC3 cut does not explain the larger  values which I obtained October 24, 2005 EMCal Recalibration Check

Slide 11 from May 10 PWG presentation Examples of Kaon mass spectra with fits Top half should be for K+ and K- in the 0.50 to 0.55 GeV/c momentum bin Mistake that the same K- spectrum and fit are shown twice Corrected by Debsankar in mail to me last week See correction next slide = 0.018 Bottom half is for the 0.90 to 0.95 GeV/c momentum bin. Also has typo error in that right “m2n” is not the K- but it is the K+ Spectrum on the left is the K- = 0.032 = 0.032 Note fit regions in mass2 essentially covering just larger than the peak region October 24, 2005 EMCal Recalibration Check

Corrected K+ mass spectrum for 0.50 to 0.55 GeV/c Background function = p0 + p1*exp(-p2*m2) Note the fit region is for mass2 from 0.18 to 0.30 The shape of the background at the high edge should arouse suspicion = 0.019 October 24, 2005 EMCal Recalibration Check

Sensitivity of Fit Results to Fit Starting Parameters Example of 0 Sensitivity of Fit Results to Fit Starting Parameters Example of 0.90-0.95 mass2 Spectrum (Using 0.145 to 0.330 fit range) K+ K- Top half: Spectra and fits as shown in PWG meeting Using PWG background function = 0.033 = 0.032 Bottom half: Same spectra but with fits as derived from different starting parameters Gives larger  and the 2/NDF is improved = 0.042 = 0.043 October 24, 2005 EMCal Recalibration Check

EMCal Recalibration Check Checks of validity of PWG background extrapolation Using fit parameters obtained from PWG study Plotting range 0.10 to 0.40 in mass2 K+ 0.50 to 0.55 GeV/c K- 0.50 to 0.55 GeV/c K- 0.90 to 0.95 GeV/c = 0.019 Backgrounds determined just under mass peak do not extrapolate accurately very far from mass peak region itself = 0.018 = 0.032 October 24, 2005 EMCal Recalibration Check

EMCal Recalibration Check Checks of stability of fitting using different mass2 ranges Compare PWG spectra for 0.50-0.55 and my own spectra Fitting range 0.10 to 0.40 in mass2 Fitting range 0.14 to 0.36 in mass2 K + K- K+ K- = 0.024 = 0.020 = 0.021 = 0.025 = 0.024 = 0.020 = 0.021 = 0.023 Fit widths, centroids, and backgrounds are stable for two wider choices of mass2 fit region October 24, 2005 EMCal Recalibration Check

EMCal Recalibration Check Checks of stability of fitting using different mass2 ranges Compare PWG spectra for 0.90-0.95 and my own spectra Fitting range 0.10 to 0.40 in mass2 Fitting range 0.14 to 0.36 in mass2 K + K- K+ K- = 0.045 = 0.045 = 0.045 = 0.045 = 0.047 = 0.044 = 0.052 = 0.047 For this momentum bin the background fit is unstable when the fit region is narrowed October 24, 2005 EMCal Recalibration Check

Kaon Centroids Compared Between East and West Arms K+ ++ field K+ -- field K- ++ field K- -- field Trends of PWG results and my results agree The PWG results were summed over East and West Arms and over the ++ and the -- fields For the -- field there is a distinct separation between East and West Arm centroids for both K+ and K- For the ++ field there is less separation especially for the K- October 24, 2005 EMCal Recalibration Check

Comparison of Kaon Widths with PWG results The PWG width results are significantly lower than my results for all particle, arm, and field combinations No big separation between East and West arm results, but there is a small separation for K+ in ++ field For the lowest momentum bins the K- widths are slightly smaller than the K+ widths, but this difference disappears at higher momentum bins October 24, 2005 EMCal Recalibration Check

Check of EMC Azimuthal Residual Centroids for Kaon m2 Azimuthal recalibration for EMCal was not completed Centroids show consistent, systematic deviation from nominal 0.0 as momentum decreases, for all charge-field sign combinations The same is true for the widths of residuals, next slide Plots are for scans not using a PC3 hit requirement October 24, 2005 EMCal Recalibration Check

Check of EMC Azimuthal Residual Widths for Kaon m2 Azimuthal recalibration for EMCal tracking was not done?? Widths show a significant deviation from nominal 1.0 as the momentum decreases The deviations are large enough to lead to a loss of efficiency even with a 3 tracking cut Plots are for scans not using a PC3 hit requirement October 24, 2005 EMCal Recalibration Check

Checking Effects of Requiring a PC3 Match October 24, 2005 EMCal Recalibration Check

EMCal Recalibration Check Sample kaon m2 spectrum without PC3 hit requirement Example from -- field runs Signal and background yields in a +/- 2 wide m2 window for 0.575 Gev/c momentum bin Part Arm Sig Bgrd S/B K+ W 4502 1954 2.30 E 2096 897 2.33 K- 5013 1883 2.67 2130 645 3.30 = 0.028 = 0.026 = 0.024 = 0.025 October 24, 2005 EMCal Recalibration Check

Sample kaon m2 spectrum with PC3 hit requirement Same -- field runs as previous slide Signal and background yields in a +/- 2 wide m2 window Part Arm Sig Bgrd S/B K+ W 3881 940 4.23 E 1957 492 3.98 K- 3999 913 4.38 1831 345 5.31 = 0.027 = 0.026 Effect of PC3 cut: Average signal loss = 14% Average S/B gain = 1.69 = 0.024 = 0.025 October 24, 2005 EMCal Recalibration Check

Sample EMC azimuthal residual without PC3 hit requirement Same -- field runs as previous slides = 1.26 c = 0.082 = 1.21 c = -0.115 = 1.14 c = -0.233 = 1.17 Fits with Gaussian + Constant Bgrnd Centroids should be nominally 0.0 and the widths should be 1.0 These are significantly not at nominal values Constant bgrnd is at a high (~10%) level? October 24, 2005 EMCal Recalibration Check

EMCal Recalibration Check Sample EMC azimuthal residual with PC3 hit requirement Same -- field runs as previous slides Fits with Gaussian + Constant Bgrnd Centroids similar to before but the  are slightly smaller Constant bgrnd level is much smaller (3%) Residuals are closer to Gaussian shapes c = 0.225 = 1.15 c = 0.096 = 1.10 c = -0.105 = 1.08 c = -0.224 = 1.14 October 24, 2005 EMCal Recalibration Check

EMCal Recalibration Check Summary Kaon particle widths derived for PWG study are too small Larger m2 fitting region will lead to larger  values We need to check the stability of the fitting results We have to re-do the EMCal recalibration mass parameters Should have separate parameterizations for East and West arms since the mass centroids are generally different between East and West There is also some difference between the ++ and the -- fields Other issues Also need to fix the tracking cut parameterizations Should investigate that use of PC3 matching PC3 was not used for Run2 because there is a loss (~15%) of yield in the single kaons and more for the pairs: Need to compare with MC Statistics not as big an issue in Run4 for the dN/dy studies NTUPLEs with 2% of particle pro.59 CNT yields available on VUPAC system including latest recalibration software We should check that this is no change with the newer pro.66 CNTs October 24, 2005 EMCal Recalibration Check