bhabha calibration at Y(3S)

-with the switch to Y(3S) running, the rolling bhabha calibration cannot be used (now)
-bhabha calibration does not calibrate on data, but on deposited Energy of Y(4S) MC, produced ~10 years ago - knowledge of the MC is lost: All that is known is the used c.m. energy
-MC deposited Energy has to be rescaled to come to reasonable results!
-bhabha calibration already contains rescaling routine, used to do a global scaling of Y(4S) beam energies to the values used for MC production
-global calibration is ok for small differences during Y(4S) running but not for Y(3S), because change of the boost:

-Caption is German - sorry for that! But: calibrating with global scaling for Y(4S) energies leads to errors for large Theta!
-Solution:
-multiplying the detector response for Y(4S) (MC) with a Scaling factor taking into accout the different Energies and Boosts for Y(3S) vs. Y(4S) running
-Rescaling the MC energies with: R=E(3S)/E(4S) = [(Etot3S^2-Ptot3S^2)/(Etot3S-Ptot3S*cos(theta))]/[(Etot4S^2-Ptot4S^2)/(Etot4S-Ptot4S*cos(theta))]...

bhabha calibration results (and problems...)

-ran offline calibration, used runs 77657-77857
-major results (just linked to the bhabha calibration results page):
-expected shift = 1.005:


-distribution vs. Theta:


-clear slope in constants vs. theta, constants drop with increasing theta!
-could be a result of the changed scaling!
-checked older calibrations, concerning the slope
-same plots for first run 6 calibration:


-similar slope (although not that clear)
-no slope for first run 5a calibration, but small slope for run5b start, looks like it appeared from time to time and was calibrated out
-checked theta dependency of E/p for EmcBumps for 25 randomly chosen runs at 3 different times: start of run 6; middle/end of run 6; start of run 7


-conclusion here: slope only in the middle of Run 6 plot
-assumption that slope is what is expected, then result of the first Run 7 bhabha calibration is reasonable!
-Shifts energies at lower theta more upwards and leaves energies at higher theta more or less unchanged...
-need to study more run ranges to make this a solid assumption
-at least it gives the impression that the calibration is not completely off

-In addition to that: Stripcharts (thanks to Michael Sigamani)
-compared E/p for the last runs of run 6 with E/p for the first runs of run 7
-Take a look at pages 9-12 of the run 6 stripcharts -the run 7 plots for the same variables can be found here at pages 75-78 -e.g. E/p EmcBump in Run6: ~0.938; for Run7: ~0.934; new bhabha calibration would lead to a shift of 1.005 --> 0.9387. Good agreement with stripcharts!

so, what's next?

-take some more test samples and try to make the assumption more solid
-in the run range used for calibration unfortunately a source calib took place - will extend the data sample and make two calibration out of the data, one before and one after the new source constants were loaded...
-will probably be finished on monday
-anyway: preliminiary results and cross checks with strip charts look good :-)