Description: The 8th International Comparison of Absolute Gravimeters (ICAG2009) took place at the headquarters of the International Bureau of Weights and Measures (BIPM) from September to October 2009. It was the first ICAG organized as a key comparison in the framework of the CIPM Mutual Recognition Arrangement of the International Committee for Weights and Measures (CIPM MRA) (CIPM 1999). ICAG2009 was composed of a Key Comparison (KC) as defined by the CIPM MRA, organized by the Consultative Committee for Mass and Related Quantities (CCM) and designated as CCM.G-K1. Participating gravimeters and their operators came from national metrology institutes (NMIs) or their designated institutes (DIs) as defined by the CIPM MRA. A Pilot Study (PS) was run in parallel in order to include gravimeters and their operators from other institutes which, while not signatories of the CIPM MRA, nevertheless play important roles in international gravimetry measurements. The aim of the CIPM MRA is to have international acceptance of the measurement capabilities of the participating institutes in various fields of metrology. The results of CCM.G-K1 thus constitute an accurate and consistent gravity reference traceable to the SI (International System of Units), which can be used as the global basis for geodetic, geophysical and metrological observations of gravity. The measurements performed afterwards by the KC participants can be referred to the international metrological reference, i.e. they are SI-traceable. The ICAG2009 was complemented by a number of associated measurements: the Relative Gravity Campaign (RGC2009), high-precision levelling and an accurate gravity survey in support of the BIPM watt balance project. The major measurements took place at the BIPM between July and October 2009. Altogether 24 institutes with 22 absolute gravimeters32 and nine relative gravimeters participated in the ICAG/RGC campaign. This paper is focused on the absolute gravity campaign. We review the history of the ICAGs and present the organization, data processing and the final results of the ICAG2009. After almost thirty years of hosting eight successive ICAGs, the CIPM decided to transfer the responsibility for piloting the future ICAGs to NMIs, although maintaining a supervisory role through its Consultative Committee for Mass and Related Quantities.

Description: Published

Description: 666–684

Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive

Description: JCR Journal

Description: restricted

Description: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy. IGETS continues the activities of the Global Geodynamics Project (GGP) between 1997 and 2015 to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. As part of this network, the Trappes station (code TR) was established in 2013 by LNE-SYRTE. Continuous time-varying gravity and atmospheric pressure data from TR are integrated in the IGETS data base hosted by ISDC (Information System and Data Centre) at GFZ. LNE-SYRTE is responsible for primary metrology missions of gravimetry in France. The gravimetry laboratory is located at 30 km at the West of Paris (longitude: 1.98 E, latitude: 48.76 N, height above MSL: 170 m) [Merlet et al. 2008, doi:10.1088/0026-1394/45/3/002] in the French National Metrology Institute LNE-Trappes. It has been designed to accommodate other gravimeters for metrological comparisons tests and calibrations and is located close to the LNE Kibble Balance for which an absolute value of g is needed [Thomas et al. doi.org/10.1088/1681-7575/aa7882]. For that purpose an absolute quantum gravimeter has been developed [Louchet-Chauvet et al. 2011, doi:10.1088/1367-2630/13/6/065025, Karcher et al. 2018, doi.org/10.1088/1367-2630/aaf07d]. To evaluate its long term sensitivity, to ensure redundancy and to guarantee the continuity of the gravity signal in case of displacement of the reference gravimeter, an SG manufactured by GWR Instruments, the iGrav#005, has been installed in the gravimetry laboratory at the beginning of 2013. With the quantum gravimeter, it allows for Planck constant determination and now for the implementation of the new definition of the kilogram [Thomas et al. doi.org/10.1088/1681-7575/aa7882]. Research activities are aimed at both improving the accuracy of the quantum instrument, of 20 nm.s-2 currently, to a level below 10 nm.s-2, and its long term sensitivity, of 0.6 nm.s-2 currently, to a level below 0.1 nm.s-2. The time series of gravity and barometric pressure from the gravimeter iGrav-005 starts in February 2013. It interrupted 3 times: from 25 of may 2018 to 4 of July 2018 due to a coldhead maintenance problem of the manufacturer; from 14 of August 2019 to 1st of October 2019 and from 1st of January 2020 to 4th of March 2020 for a CPU problem. The time sampling of the raw gravity and barometric pressure data of IGETS Level 1 is both 1 minute and 1 second. For a detailed description of the IGETS data base and the provided files see Voigt et al. (2016, http://doi.org/10.2312/GFZ.b103-16087). Moreover the laboratory is also equipped with a permanent GNSS (Global Navigation Satellite Systems) antenna LNE1 belonging of the RENAG network (RESIF-RENAG French National Geodetic Network, RESIF – Réseau Sismologique et Géodésique Français, https://doi.org/10.15778/resif.rg, 2017) which is the French contribution to EPOS for the Seismology and Geodesy components.