Speaker
Description
The Timepix3 detector network installed inside the ATLAS cavern [1] has demonstrated reliable performance for measuring particle fluxes and monitoring luminosity during LHC operations [2, 4]. Comprising fourteen operational detectors distributed throughout the ATLAS experiment, the network is exposed to diverse radiation fields and flux levels. Detectors closer to the interaction point provide high-statistics measurements, while those at greater distances enable systematic uncertainty assessment.
Operating independently, the network is fully synchronized with the LHC orbit clock, allowing bunch-sensitive, real-time luminosity measurements. Furthermore, individual Timepix3 detectors provide detailed cluster analysis, enabling their classification into minimum ionizing particles, highly ionizing particles, gamma rays, neutrons, and electrons, as well as the reconstruction of particle trajectories. These capabilities are used to characterize the radiation environment [3] and to separate the collision peak in each bunch crossing, mitigating background and significantly improving the signal-to-background ratio [4].
This contribution presents the internal stability and performance of the Timepix3 network throughout 2025, alongside detailed measurements and analysis taken during the van der Meer (vdM) scans. Since the vdM scans provide the primary reference for absolute luminosity calibration and cross-section calculation, these studies show the potential of the Timepix3 network to contribute directly to absolute luminosity determination. Initial fits to the scan profiles confirm the consistency and reliability of the data collection.
Overall, these results demonstrate that the Timepix3 detector network is a versatile tool for both online and offline beam monitoring, positioning it as a strong, independent, and complementary candidate for luminosity calibration and long-term monitoring in luminosity LHC operations.
[1] P. Burian et al. “Timepix3 detector network at ATLAS experiment” JINST 13 C11024 (2018) \url{https://iopscience.iop.org/article/10.1088/1748-0221/13/11/C11024/meta}
[2] B. Bergmann et al., “Relative luminosity measurement with Timepix3 in ATLAS” JINST 15 C01039 (2020). \url{https://iopscience.iop.org/article/10.1088/1748-0221/15/01/C01039/meta}
[3] B. Bergmann et al., “Characterization of the Radiation Field in the ATLAS Experiment with Timepix Detectors”, in IEEE Transactions on Nuclear Science 66, no. 7, pp. 1861-1869 (2019) \url{https://ieeexplore.ieee.org/abstract/document/8720202}
[4] B. Bergmann et al., “Evaluation of Timepix3 as a luminosity detector at LHC during 2018 pp collisions at \sqrt{s}=13 TeV” Eur. Phys. J. C 85, 904 (2025). \url{https://doi.org/10.1140/epjc/s10052-025-14631-x}