Improved algorithms for determination of particle directions with Timepix3.

Timepix3 pixel detectors have demonstrated great potential for tracking applications. With $256\times 256$ pixels, 55 $\mathrm{\mu}$m pitch and improved resolution in time (1.56 ns) and energy (2 keV at 60 keV), they have become powerful instruments for characterization of unknown radiation fields. A crucial pre-processing step for such analysis is determination of particle trajectories in 3D space from individual tracks. This study presents a comprehensive comparison of regression methods that tackle this task under the assumption of track linearity. Proposed methods were first evaluated on a simulation and assessed by their accuracy and computational time. Selected methods were then validated with a real-world dataset, which was measured in a well-known radiation field. Finally, the presented methods were applied to experimental data from the Large Hardron Collider. The best-performing methods achieved mean absolute error of 1.99{\deg} and 3.90{\deg} in incidence angle $\theta$ and azimuth $\varphi$, respectively. The fastest presented method required mean computational time of 0.02 ps per track. For all experimental applications, we present angular maps and stopping power spectra.