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Run21 OO 200 GeV BTOF and VPD Calibrations

Updated on Wed, 2025-07-09 17:04. Originally created by dtorresva on 2025-06-26 14:27.

This page presents summary PDF files comparing the performance of VPDstart and Startless modes for the Run21 O+O 200 GeV FF and RFF datasets. The calibrations focus on both the BTOF and VPD systems.

Two key observations from the analysis are highlighted:

  • Improved T0 Resolution: The STARTLESS mode shows a higher T0 resolution compared to the VPDSTART mode in both datasets.

  • Proton Mass Splitting: A clear observation of proton mass splitting has been made. This splitting is more evident in the RFF dataset.

  • zLocal Shifts Bands: zLocal bands appear outside the normal zLocal distribution in both FF and RFF (more clearly observed in FF dataset).

Please refer to the attached summary files for further details.

VPD Calibration

Reverse Full Field (FF)


Full Field (RFF)

To further analyze what could be causing these bands, I examined the Zlocal hits across different ranges in the FF dataset, as it exhibits the most prominent bands outside the (–3, 3) range. I focused in particular on Tray 60, one of the trays showing this band-shift effect. However, no clear pattern was found.

STAR/system/files/userfiles/6735/oo200GeV_FF_RunID_vs_ZLocal(1).pdf


The bin mapping to Run Id can be found in the following files:

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