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Run21 OO 200 GeV BTOF and VPD Calibrations

Updated on Mon, 2025-08-18 10:23. 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)

The additional horizontal bands appear to be caused by secondary hits in the bTOF detector. When restricting the calibration for the full-field (FF) dataset to tracks with matchflag = 1, these secondary bands disappear, confirming that they are related to non-primary or ambiguous hit associations. However, the vertical dips across trays remain visible even after applying this stricter cut.

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