1. Problems with the Run4 Preliminary Phi->KK Analysis
EMCal checks so far
Particle ID widths for IsKaon function were too small
Track association residual distributions were calibrated for kaons
Azimuthal centroids are significantly different from 0.0 at lower momentum
Azimuthal widths are significantly larger than 1.0 at lower momentum
Z centroids seem to be OK (but is there a Z-depencence?)
Z widths are also significantly different from 0.0
Initial fiducial volume systematic checks show large variations (Monday)
We must understand completely any fiducial volume effect change on the pairs This means understanding the changes which we see in the singles
Fiducial volume studies need to be re-done after the fixes are made in the particle ID and the track association cuts
TOF checks so far
Also saw IsKaon width discrepancies at low momentum
Tracking residual discrepancies do not seem to be as severe as in EMCal
Fiducial volume studies also show significant changes in acceptance
Anything we conclude for TOF-TOF has to be confirmed by the WIS group
Summary
Much work needed before we can show any new numbers to the L/H PWG
November 9, 2005
EMCal Recalibration Homework

2. EMCal Recalibration Homework
Homework from Checks of Current EMC Recalib Results for Kaon Mass and Tracking Residuals (Nov 03 L/H PWG)
Show sample EMCal mass spectrum at low momentum
Question from Sasha Milov on how good a mass signal we have
Giving examples of 425 +/- 25 MeV/c momentum bin (see slide 2)
Fit with two different background functions, results essentially stable for <m> and 
Try track residual fits with two Gauss peaks (instead of constant bgrnd)
First gauss peak is for the true associations, other is false matches
True association peak should have width of ~1.0
Giving examples for pions (slide 4) and for kaons (slide 7)
Check the slide & swap residual distribution (not yet done)
Expectation that width of slide & swap corresponds to the second Gauss peak width
Summary of November 03 homework checks
Even the pion residual distribution in azimuth shows an offset from 0.0
The first Gauss peak for the pions does have a width of 1.0
The fit results for the kaon azimuthal residual width with a double Gaussian are similar to the fits with a signal Gaussian plus a constant background
The centroids and widths of the kaon azimuthal residual are consistently different from those of the pion residual when compared at this momentum bin
November 9, 2005
EMCal Recalibration Homework

3. EMCal Recalibration Homework
Sample Mass Spectra from EMCal with stable fits Example from ++ field data and p = 425 +/- 25 MeV/c
K+ [bgrnd = p0 + p1*exp(-p2*m2)] K K+ [bgrnd = p0 + p1/m2 + p2/m4] K-
c = 0.241
= 0.024
c = 0.246
= 0.023
c = 0.231
= 0.016
c = 0.231
= 0.016
c = 0.233
= 0.018
c = 0.246
= 0.022
c = 0.233
= 0.017
c = 0.246
= 0.023
November 9, 2005
EMCal Recalibration Homework

4. EMCal Recalibration Homework
Comparison of Kaon Widths with May 10 results The May 10 width results determine the CNT IsKaon function values
The May 10 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
November 9, 2005
EMCal Recalibration Homework

5. EMCal Recalibration Homework
Fits to Kaon Azimuthal Residual Distribution Examples from ++ data and p = 425 +/- 25 MeV/c
+ double Gauss fits  + single Gauss + const bg -
c = -0.56
= 1.45
= 2.58
c = +0.61
= 1.39
= 3.26
c = -0.51
= 1.56
bg= 2.7
c = +0.59
= 1.44
bg= 2.4
c = -0.69
= 1.40
= 2.99
c = -0.64
= 1.49
bg= 1.8
c = +0.42
= 1.42
bg = 1.7
c = +0.44
= 1.34
= 2.94
K peaks (red) have centroids with larger <c> shifts and larger  than seen for 
Fits with double Gauss or single Gauss + constant bg give about the same results
November 9, 2005
EMCal Recalibration Homework

6. 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
November 9, 2005
EMCal Recalibration Homework

7. 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
November 9, 2005
EMCal Recalibration Homework

8. Double Gauss fits to Pion Azimuthal Residual Distribution Examples from ++ and -- field data and p = 425 +/- 25 MeV/c
+ ++ field runs - ++ field runs + -- field runs - -- field runs
c = -0.28
= 1.00
= 2.09
c = +0.27
= 2.07
c = +0.23
= 1.98
c = -0.29
= 1.04
= 2.00
c = +0.26
= 1.00
= 2.06
c = -0.27
= 0.98
= 2.02
c = -0.27
= 1.02
= 2.11
c = +0.24
= 1.01
= 2.13
Primary peaks (red) have centroids shifted from 0.0 but  are 1.0
November 9, 2005
EMCal Recalibration Homework

9. EMCal Recalibration Homework
Check of Current EMC Recalib Results for Kaon Mass and Tracking Residuals [repeat from Nov. 3]
Original EMC recalibration presentation written on May
Important to check this as part of confirming the Phi->KK yields in Run4
May 10 analysis determined the EMCal particle ID function CNT parameter (IsKaon) based on fits to mass spectra in each momentum bin
No check was done on May 10 of the tracking residual parameters
Analyses assume that the tracking residual and the IsKaon distributions are Gaussians centered at 0.0 with a 1.0 standard deviation width
Initial check for kaons shown at local group meeting 2 weeks ago
My mass width results were ~30% larger than the May 10 values (next slide)
Differences in two analyses of the EMCal mass spectra
Different background function choices for the underlying pion contributions
Different mass fit regions for each momentum bin
Results of checks of effects of differences done past 2 weeks
Background function difference does not lead to different fit widths
May 10 results are not stable with respect to size of mass fit region (slide 7) Not enough representative satellite channels for background
November 9, 2005
EMCal Recalibration Homework

10. Slide 11 from May 10 presentation Mass fits for two momentum bins for K+ and K-
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 minor 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
November 9, 2005
EMCal Recalibration Homework

11. 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 The shape of the background at the high edge should arouse suspicion
= 0.019
November 9, 2005
EMCal Recalibration Homework

12. Sensitivity of Fit Results to Fit Starting Parameters Example of 0
Sensitivity of Fit Results to Fit Starting Parameters Example of mass2 Spectrum (Using to fit range) K+ K-
Top half: Spectra and fits as shown in May 10 meeting Using May 10 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
November 9, 2005
EMCal Recalibration Homework

13. EMCal Recalibration Homework
Checks of validity of May 10 background extrapolation Using fit parameters obtained from May 10 study
Plotting range 0.10 to 0.40 in mass2
K to 0.55 GeV/c
K to 0.55 GeV/c
K 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
November 9, 2005
EMCal Recalibration Homework

14. EMCal Recalibration Homework
Checks of stability of fitting using different mass2 ranges Compare May 10 spectra for and my own spectra
Fitting range 0.10 to 0.40 in mass 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
November 9, 2005
EMCal Recalibration Homework

15. EMCal Recalibration Homework
Checks of stability of fitting using different mass2 ranges Compare May 10 spectra for and my own spectra
Fitting range 0.10 to 0.40 in mass 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
November 9, 2005
EMCal Recalibration Homework

16. Kaon Centroids Compared Between East and West Arms
K+ ++ field
K+ -- field
K- ++ field
K- -- field
Trends of May 10 results and my results agree
The May 10 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-
November 9, 2005
EMCal Recalibration Homework

17. Check of EMC Zed Residual Centroids for Kaon m2
Zed centroids OK
Deviations from 0.0 are not significant compared to the 3 widths (next slide)
November 9, 2005
EMCal Recalibration Homework

18. Check of EMC Zed Residual Widths for Kaon m2
Zed widths deviate significantly from 1.0 at low momentum
Deviations for the K- are slightly less than for the K+ for both field signs
November 9, 2005
EMCal Recalibration Homework

19. EMCal Recalibration Homework
Summary
EMC Kaon particle widths derived for May 10 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
We need to fix the EMC tracking cut parameterizations
We should check that this is no change with the newer pro.66 CNTs
Also re-checking the TOF recalibration results and fiducial cuts
After new recalibrations parameters are introduced then the Phi->KK yield analysis will be re-done
Should re-do the Phi->KK v2 analysis
November 9, 2005
EMCal Recalibration Homework