Status of the INRIM-VMI Collaboration on the Use of Galactic Cosmic Rays for Time Metrology Applications

In this work, we present the status of the ongoing scientific collaboration between INRIM （Istituto Nazionale di Ricerca Metrologica） and VMI （International Virtual Muography Institute） on the possibility of synchronizing atomic clocks and disseminating reference atomic time scales using relativistic charged particles, muons, from cosmic rays induced Extended Air Showers （EAS）, through an approach called CTS （Cosmic Time Synchronizer）, ideated by the University of Tokyo. Based on muons, this system aims to grant timing services within the EAS shower disc with improved robustness and reliability against consolidated time synchronization systems. The CTS approach is, in principle, not affected by malicious or intentional jamming and spoofing actions, typically undermining time synchronization techniques based on the use of RF （Radio Frequency） signals, like those emitted by GPS （Global Positioning System） and other GNSS （Global Navigation Satellite Systems） satellites. This reliability makes CTS a good candidate for providing secure synchronization and dissemination of reference time in critical applications. In addition, it could complement GNSS in areas/environments not covered by its RF signals, such as indoors, underground, and underwater.