P-ONE-1: the first detector line of the Pacific Ocean Neutrino Experiment
Neutrino telescopes instrument optically transparent media with three-dimensional arrays of photosensors to detect Cherenkov radiation induced by neutrino interactions within or near the instrumented volume. The small cross-sections of the weak interaction and the low neutrino fluxes above TeV energies require vast detector volumes, which only natural media on Earth can realistically provide. Spurred by the detection of the first neutrino sources by the IceCube Neutrino Observatory, a new generation of neutrino telescopes is emerging to increase the global instrumented volume and detection sensitivity. The Pacific Ocean Neutrino Experiment (P-ONE) aims to install such a telescope in the Northeast Pacific Ocean, building on established neutrino telescope design targets in collaboration with Ocean Networks Canada (ONC). This article presents the design, integration, and testing of the first P-ONE line, P-ONE-1, in preparation for its deployment and integration into ONC's deep-sea observatory NEPTUNE. Alongside the detector design and integration methods, we detail in-air and in-water system-level validation performed at several test sites in Canada, culminating in the successful construction of P-ONE-1 and its preparation for deployment.