Dynamic positioning and orientation calibration for the KM3NeT detectors

The KM3NeT infrastructure comprises two water Cherenkov detectors in the Mediterranean Sea. Each detector consists of an array of optical modules that are subject to movement due to deep-sea currents. To ensure an accurate reconstruction of neutrino events, the position and orientation of each optical module needs to be monitored continuously. This is performed by means of a dedicated positioning system, composed of acoustic emitters placed on the seabed, and acoustic receivers integrated into the optical modules. The dynamic positions of the detector elements are determined via a global fit to the acoustic data. To achieve the envisaged angular resolution of 0.05 degrees in KM3NeT/ARCA, the position of each optical module must be resolved with an accuracy better than 20 cm. The orientations of the optical modules are determined using compass data and need to be resolved with an accuracy of about three degrees. This contribution presents the global fit method that is currently used for the positioning calibration in both KM3NeT telescopes, ARCA and ORCA. The movement of the detection units is shown as a function of time and compared to sea current measurements. Furthermore, the impact of dynamic positioning calibration on the accuracy of the reconstructed direction is studied for ARCA.