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["Van Buren, Gene" <gene AT bnl.gov>]

Thank you for the detailed reports, Chenliang. These do appear to indicate some remaining mis-calibration of the TPC in the Run 19 AuAu 19.6 GeV dataset (which to be clear is RFF). The observation of larger mass-splitting for positive eta tracks than negative
 eta tracks prompted me to have a look at whether there was any possible east-west asymmetry in the TPC SpaceCharge which I had not accounted...

The attached plots show...

(1) the difference in SpaceCharge measured from west-side-only tracks vs. east-side only tracks vs. luminosity, using the overall measured SpaceCharge as a proxy for luminosity

(2) same as (1) but difference in <sDCA> between the west and east sides

(3) same as (1) but ZDC coincidence rate as a proxy for luminosity

In none of these do I see any significant luminosity dependence, but I do see an apparent west-vs-east offset. A static offset points to a difference in a static calibration between the two sides, such as alignment or static field distortions, not to SpaceCharge asymmetry.

An additional observation comes from my h-/h+ ratio measurements for the 19.6 GeV data:

https://drupal.star.bnl.gov/STAR/blog/genevb/h-h-Run-19-196-GeV-new-TPC-alignment

...and more specifically this plot:

https://drupal.star.bnl.gov/STAR/system/files/userfiles/17/image/Calibrations/TPC_Alignment/hmhp/Run19/hminus_hplus_exponentParametersP24iy.png

If I count sectors above and below zero (where zero is by definition the average of all sectors), then I find...

West side sectors (1-12): 3 are well below zero, 3 are near zero, 6 are well above zero, so a net "well above zero" result

East side sectors (13-24): 8 or 9 are well below zero, 1 or 2 are near zero, 2 are well above zero, so a net "well below zero" result

So my overall conclusion, agreeing with the BTOF mass-splitting observation, is that there are remaining east-vs-west static TPC calibration differences.

Thanks,

-Gene

On Nov 27, 2024, at 4:04 PM, Chenliang Jin <cj17 AT rice.edu> wrote:

Dear Gene and all,

We have finished BTOF calibration for Run19 AuAu 19.6GeV data with new TPC alignment. BTOF T0 and geometry behaviour are good now and we plan to use these new parameter tables to check FXT datasets. 

But we find an issue about the charged particle mass splitting for this dataset similar as previous Run21 OO 200GeV. The splitting is large in positive Eta range and small in negative Eta range. Here are the slides for Run19 19.6GeV BTOF calibration in the attachment together with previous Run21 OO 200GeV report using this link:https://drupal.star.bnl.gov/STAR/system/files/VPD_BTOF_Calibrations_OO_Chenliang_0412_SC.pdf . 

And this is the Drupal link for Detailed QA report: https://drupal.star.bnl.gov/STAR/system/files/tofCalibSummary_Run19_AuAu19GeV_startless_newalign_p1.pdf

Sincerely,
Chenliang Jin

<BTOF calibration for Run19 19.6GeV with new TPC alignment.pdf>