The BIPM, the Time Department and UTC Elisa Felicitas Arias Fundamentals for a time and frequency laboratory BIPM, 11 September 2012
BUREAU INTERNATIONAL DES POIDS ET MESURES The BIPM It has headquarters near Paris, France. It is financed jointly by the Member States (56) and Associates (37), and operates under the exclusive supervision of the CIPM. Its mandate is to provide the basis for a single, coherent system of measurements throughout the world, traceable to the International System of Units (SI). This task takes many forms, from direct dissemination of units (as in the case of mass and time) to coordination through international comparisons of national measurement standards (as in length, electricity and ionizing radiation). It maintains scientific laboratories in areas of: mass, time, electricity, ionizing radiation, and chemistry. It has an international staff of over 70 and its status vis-à-vis the French Government is similar to that of other intergovernmental organizations. 2
METROLOGY AND SOCIETY Increasing need of reliable measurements; Expansion of metrology to new areas Health Safety Environment Communications More requirements Time and Frequency Nanometrology Traceability (food, medicine, environment) 3
Time National institutes: Maintain local atomic timescales UTC(k) Realize the SI second (PFS) BIPM: Maintenance and dissemination of the international time scale UTC whose unit interval is the SI second 4
PUBLICATIONS Metrologia is an international journal dealing with the scientific aspects of metrology The SI Brochure. The BIPM disseminates the time scales and gives traceability to UTC to participating laboratories through the monthly BIPM Circular T. The Annual report on Time Activities gives definitive results and complete information on TAI and UTC (only web version). 5
Time Department staff Felicitas Arias - Director Hawaï Konaté Principal Technician Aurélie Harmegnies Assistant Zhiheng Jiang - Principal Physicist Wlodek Lewandowski - Principal Physicist Gianna Panfilo - Physicist Gérard Petit- Principal Physicist Lennart Robertsson- Principal Physicist Laurent Tisserand - Principal Technician
UTC Coordinated Universal Time Coordinated broadcast of time signals (ITU-R) Universal Time (UT) was the name of the time scale derived from the apparent daily motion of the Sun; Universal referred to «the same for all the world» TAI differs from UTC in an integral number of seconds Leap second announcement is the responsibility of the IERS 7
Each month: 69 participants ~400 clocks, one measurement / 5 days, t&f corr. monthly ftp server 13 primary freq. standard data monthly ~180 time transfer files daily, weekly, monthly Data submission deadline 4/mm/yy/ Datation is in «Modified Julian Date», a contiuous count of days since an arbitrary origin 8
Elaboration of TAI and UTC - ALGOS 400 atomic clocks in 70 laboratories average EAL Echelle Atomique Libre 13 primary frequency standards (8 labs) steering TAI freq stability 0.4 x 10-15 @30-40 days Temps Atomique International Measurement of Earth s rotation (IERS) leap seconds freq accuracy ~10-15 UTC(k) Circular T UTC Temps Universel Coordonné Role of the BIPM 9
Participating laboratories and their time transfer equipment
Improving UTC for the 21 st century applications Better clocks (in labs) New primary frequency standards (in labs) Optical frequency standards (in labs) Accurate time and frequency transfer (labs, BIPM) Improved clock comparisons by refining time transfer (labs, BIPM) Improved algorithms (labs for UTC(k), BIPM for UTC) Providing UTC more frequently (BIPM Rapid UTC project) Impact on UTC(k) Impact on steering GNSS times to a representation of UTC Rendering UTC continuous (ITU)
Many thanks for your attention!