Time Metrology for Fundamental Physics Experiments: INRIM’s Experience with the FRATERNISE Project
G. Cerretto, E. Cantoni, M. Sellone, Istituto Nazionale di Ricerca Metrologica; I. Gnesi, UniTo - Dipartimento di Management, | Centro Studi Enrico Fermi, CREF | INFN, Laboratori Nazionali di Frascati, | CERN; In collaboration with E. Bertacco, F. Pollastri, A. Gerace, H.K.M. Tanaka
Location: Beacon B
Date/Time: Wednesday, Jan. 24, 4:46 p.m.
Time Laboratories are facilities typically hosted at National Metrology Institutes (NMI) and Astronomical Observatories, aimed at developing and operating innovative methods and techniques for generating and measuring accurate time and time intervals. In Italy, this role is carried out by INRIM Time Laboratory, whose main tasks are related to the contribution to the implementation of TAI/UTC international time scales by the BIPM and to the generation of UTC(IT), the Italian Standard Time. Its dissemination to final users through NTP and White Rabbit technique, the regular provision of Certification Services for the Italian industries under the CIPM Mutual Recognition Agreement, together with the participation in the design and development of the timing aspects of the Galileo system, represent the main contributions provided by the Laboratory towards the national and international high-level production sectors. However, in such a context, fundamental-level research activities become crucial to improve the Laboratory’s metrological capabilities and support a wide range of scientific experiments requiring accurate time. Concerning the latter aspect, INRIM Time Laboratory provided its support to essential Particle Physics and Astrophysics experiments over the years, namely Borexino for the measurement of the neutrino velocity over the CERN-Gran Sasso baseline in 2012 and EEE (Extreme Energy Events) for the detection of high-energy cosmic showers, in 2020. The FRATERNISE project (Facility ad elevata accuRAtezza Temporale pEr espeRimeNti di fISicafondamEntale - High Accuracy Timing Facility for Fundamental Physics Esperiments) was born because of such experience and aims at establishing a permanent facility, installed at INRIM, dedicated to the metrological characterization and calibration of timing devices for Fundamental Physics experiments and GNSS receivers used in the remote comparison of atomic clocks or time scales. In Fundamental Physics experiments (space physics, accelerator physics), time plays a crucial role, allowing the evaluation of the events timestamping (timing) and their simultaneity, thus enabling deductions about the characteristics of the observed phenomena. Furthermore, it is increasingly necessary to correlate events from experiments that occur over large distances or events measured by different experiments located in distant places investigating similar phenomena. The FRATERNISE project contributes to optimizing timing systems for these types of experiments, assessing the possibility of synchronizing them with the Italian atomic reference time scale, UTC(IT). In addition to the permanent facility, implementing "traveling" units with "customized" functional and metrological characteristics was part of the project to calibrate timing devices that cannot be physically transported to INRIM. One of these units will also be optimized to be used as a traveling calibration station for GNSS systems used in Time Laboratories of NMI for the remote comparison of atomic clocks and time scales within the framework of international calibration campaigns organized by BIPM/EURAMET. The facility will remain operational beyond the project's end to consolidate its purposes and become a practical and functional system for the metrological characterization of timing devices used in Fundamental Physics experiments. To achieve this goal, a survey of the timing needs of the Particle Physics and Astrophysics community has been conducted through contact with various research groups to identify the main requirements and drivers of the experiments they are engaged in.