Long-term monitoring of the ANTARES optical module efficiencies using 40K decays in sea water Díaz García, Antonio Francisco Albert, A. Navas Concha, Sergio Antares Collaboration Cherenkov light induced by radioactive decay products is one of the major sources of background light for deep-sea neutrino telescopes such as ANTARES. These decays are at the same time a powerful calibration source. Using data collected by the ANTARES neutrino telescope from mid 2008 to 2017, the time evolution of the photon detection efficiency of optical modules is studied. A modest loss of only 20% in 9 years is observed. The relative time calibration between adjacent modules is derived as well. 2019-11-26T11:23:32Z 2019-11-26T11:23:32Z 2018 info:eu-repo/semantics/article Albert, A., André, M., Anghinolfi, M., Anton, G., Ardid, M., Aubert, J. J., ... & Basa, S. (2018). Long-term monitoring of the ANTARES optical module efficiencies using $$^{40}\mathrm {{K}} $$ decays in sea water. The European Physical Journal C, 78(8), 669. http://hdl.handle.net/10481/58076 10.1140/epjc/s10052-018-6132-2 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España Springer Nature