Ongoing Commissioning of the ToF Detector for the T2K ND280 Upgrade

The T2K ND280 upgrade aims to reduce systematic uncertainties affecting the oscillation analysis, enhancing the experiment’s sensitivity to CP violation in the lepton sector. As part of this upgrade, the existing $\pi^0$ detector (P0D) is replaced with three new detectors: the Super Fine-Grained Detector (SFGD) sandwiched between two High-Angle Time Projection Chambers (HA-TPCs), all enclosed by the Time-of-Flight (ToF) detector. The ToF detector plays a crucial role by providing precise timing information for particle tracks, allowing for the discrimination of background particles from those generated within the fiducial volume, thereby reducing one of the main backgrounds in ND280 analyses.

This project focused on examining the first cosmic-ray and beam data (sand muons) recorded by the newly installed ToF detector, which is essential for its tuning and calibration. Preliminary results revealed a misalignment in the ToF system and provided insights into beam behavior, both critical for ongoing detector commissioning. These findings will help optimize the ToF detector’s performance, ensuring it meets the upgrade’s goals of improved particle identification and reduced background noise in future analyses. By addressing this issue, the calibration process can now be fine-tuned, ensuring that future analyses of particle interactions are more reliable.