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DoE for the gravimeters participating in the KC (surrounded by a rectangular box) and PS (the FG5-230 excluded). Absolute measurements corrected for the self-attraction, laser beam diffraction effects and geophysical gravity changes observed with the SG.
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We present the results of the third European Comparison of Absolute Gravimeters held in Walferdange, Grand Duchy of Luxembourg, in November 2011. Twenty-two gravimeters from both metrological and non-metrological institutes are compared. For the first time, corrections for the laser beam diffraction and the self-attraction of the gravimeters are im...
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Different geophysical tools such as magnetic, gravity and geoelectric have been applied to detect groundwater potentiality and structural elements, which controlled a geometry of the groundwater aquifers in the study area. The first method is Magnetic Method to determine the depth of basement rocks, which indicates on the thickness of sedimentary c...
Citations
... CAGs have participated in several comparisons of absolute gravimeters, comparing favourably with other technologies. The cold atom gravimeter (LNE-SYRTE) has been participating in international comparisons of absolute gravimeters since 2009 [87][88][89]. Another CAG participated in the first Asia-Pacific Comparison of Absolute Gravimeters, hosted by the National Institute of Metrology of China from December 2015 to March 2016 [90]. ...
Gravity sensing is a valuable technique used for several applications, including fundamental physics, civil engineering, metrology, geology, and resource exploration. While classical gravimeters have proven useful, they face limitations, such as mechanical wear on the test masses, resulting in drift, and limited measurement speeds, hindering their use for long-term monitoring, as well as the need to average out microseismic vibrations, limiting their speed of data acquisition. Emerging sensors based on atom interferometry for gravity measurements could offer promising solutions to these limitations, and are currently advancing towards portable devices for real-world applications. This article provides a brief state-of-the-art review of portable atom interferometry-based quantum sensors and provides a perspective on routes towards improved sensors.
... The CAG also operates in this laboratory since the end of the CIPM Key Comparison CCM.G-K1 which occurred during ICAG'09 (Jiang 2012). Since then, we have been continuously working at improving the instrument performance, except when participating to comparisons in other laboratories (Francis 2013(Francis , 2015 or demonstrating the capabilities of atom interferometers in the LSBB underground facility for the MIGA project (Geiger et al. 2015). We performed a 1-month-long gravity measurement performed simultaneously by the iGrav005 1 and the 1 doi.org/10.5880/igets.tr.l1.001 ...
We present a 27-day-long common view measurement of an absolute cold atom gravimeter (CAG) and a relative iGrav superconducting gravimeter, which we use to calibrate the iGrav scale factor. This allowed us to push the CAG long-term stability down to the level of 0.5 nm s. We investigate the impact of the duration of the measurement on the uncertainty in the determination of the correlation factor and show that it is limited to about 3‰ by the coloured noise of our cold atom gravimeter. A 3-day-long measurement session with an additional FG5X absolute gravimeter allows us to directly compare the calibration results obtained with two different absolute meters. Based on our analysis, we expect that with an improvement of its long-term stability, the CAG will allow to calibrate the iGrav scale factor to better than the per mille level (1 level of confidence) after only 1 day of concurrent measurements for maximum tidal amplitudes.
... Since the measurement of gravity is dependent on instrumentation, as well as spatial and temporal variables, no estimation of the accuracy of the instruments is possible. To quantify results of absolute gravimeters the best solution is to obtain relative offsets between instruments during international gravimeter comparisons (Francis et al. 2013 (Francis et al. 2013). Since FG5-229 was found to be in very close agreement (0.2˙1 Gal) with FG5-216, the offset of C1.8 has been used for FG5-229. ...
... Since the measurement of gravity is dependent on instrumentation, as well as spatial and temporal variables, no estimation of the accuracy of the instruments is possible. To quantify results of absolute gravimeters the best solution is to obtain relative offsets between instruments during international gravimeter comparisons (Francis et al. 2013 (Francis et al. 2013). Since FG5-229 was found to be in very close agreement (0.2˙1 Gal) with FG5-216, the offset of C1.8 has been used for FG5-229. ...
Absolute gravity measurements taken on a near-weekly basis at a single location is a rarity. Twelve years of data at the UK’s Space Geodesy Facility (SGF) provides evidence to show that the application of results from international comparisons of absolute gravimeters should be applied to data and are critical to the interpretation of theSGF gravity time series of data from 2007 to 2019. Though residual biases in the data are seen. The SGF time series comprises near weekly data, with exceptions for manufacturer services and participation in international instrument comparisons. Each data set comprises hourly data taken over 1 day, with between 100 and 200 drops per hour. Environmental modelling indicates that the annual groundwater variation at SGFof some 2 m influences the gravity data by 3.1 μGal, based upon some measured and estimated soil parameters. The soil parameters were also used in the calculation of the effect of an additional telescope dome, built above the gravity laboratory, and have been shown to be realistic. Sited in close proximity to the long-established satellite laser ranging (SLR) system and the global navigation satellite systems (GNSS) the absolute gravimetry (AG) measurements provide a complimentary geodetic technique, which is non space-based. The SLR-derived height time series provides an independent measurement of vertical motion at the site which may be used to assess the AG results, which are impacted by ground motion as well as mass changes above and below the instruments.
... A laboratory realisation, the Cold Atom Gravimeter (CAG) developed at LNE-SYRTE in the context of the Kibble balance has demonstrated unprecedented performances both in sensitivity and accuracy. at International Comparisons of Absolute Gravimeters (ICAG) showing a better short-term sensitivity than absolute gravimeters and a well quantified accuracy budget(Jiang et al. (2012);Francis et al. (2013);Gillot et al. (2014)).Numerous research institutions and private companies work on different realisations of cold atom gravimeters(Geiger et al. (2020)) such as GAIN (Germany;Hauth et al. (2013)) or WAG-H5-1 (China;Huang et al. (2019)). ...
Quantum gravimeters provide the possibility of continuous, high-frequency absolute gravity monitoring while remaining user-friendly and transportable. This thesis assessed high precision performance measures of the first commercial absolute quantum gravimeters AQG#A01 and AQG#B01 developed by Muquans. This was carried out in comparison with high precision absolute and relative gravimeters and additional geophysical and environmental data, in controlled conditions and experiments in view of future deployment in field conditions.Both AQG devices allow stable measurements of g of several weeks. Significant drifts in time have not been observed. The two instruments have been transported and re-installed several times between sites and had been successfully applied in different conditions. The sensitivity of the AQG#A01 is better than 10 nm/s² after 24 h, which the AQG#B01 achieves after only one hour in a calm environment. For noisier environments, the sensitivity after one hour of the AQG#B01 is 20 to 30 nm/s². The repeatability of the AQG#B01 is reported as better than 50 nm/s². Changes of instrument tilt and external temperature (20 - 30 °C) and combination of both did not influence the measurement of gravitational attraction. These results were also confirmed during two weeks of acquisition in an urban garage during which the measurement of g remained unaffected by fast temperature changes.A rainfall event at the Larzac geodetic observatory caused a gravity increase of 100 nm/s² in December 2019, which was detected with the AQG#B01 in agreement with the superconducting relative gravimeter (GWR, iGrav#002) and corresponding Bouguer slab approximation. The potential gain in precision and time saved makes the AQG#B01 a promising instrument for e.g. large-scale gravity mapping. Such studies were formerly only feasible using a relative gravimeter that requires repeated acquisition loops and a reference absolute gravimeter for drift corrections. The AQG#B01 can be used without a reference instrument: It provides stable, repeatable measurements of absolute gravity while being transportable and user-friendly. Continuous monitoring at high precision allows for studies of high temporal resolution at different scales. The AQG#B01 would especially be suited for the monitoring of transient mass changes at durations (e.g. a few weeks) that are too short to justify the effort of installing a stationary, superconducting gravimeter. To reliably detect transient phenomena, a drift-free and repeatable determination of g is required for which e.g. spring relative gravimeters are not suitable. There are aspects that are still under investigations, such as the potential effect of the sensor head's orientation, the Coriolis effect, on the measurement of g and the assessment of the accuracy in view of differences between the AQG#B01 and the absolute gravimeter (Micro-g LaCoste, FG5#228) that is used as a reference.Time-lapse ground-based gravimetry is increasingly applied in subsurface hydrology to monitor water storage dynamics. The complementary spatial sensitivities of gravity and vertical gravity gradients (VGG) can be used to deduct the spatial characteristics of subsurface mass changes. VGG were estimated from one year of monthly relative gravity surveys on three different heights on three locations inside the Larzac observatory. The repeatability of VGG estimations was found to be better than 23 ± 9 E. The study suggests the influence of heterogeneous soil saturation patterns on VGG and the potential of differential VGG monitoring in resolving spatial mass distributions. Observed time-lapse, differential VGG changes provided additional constraints to the subsurface model. Combined VGG and gravity monitoring in hydrogeology is a promising new approach for hydrogeophysical subsurface imaging, which could find practical application in gravity monitoring during hydraulic aquifer testing.
... Thus, a strategy to reduce the measurements of the 16 AG campaigns at OSO could be laid out which might appear as unorthodox as bold: all drop observations, 199,542 in total, are reduced using the SG data and its inferred drift function; orientation biases individually for each meter (180 • reorientation from north to south is to eliminate the Eötvös effect, Křen et al. (2018)); a meter bias, i.e. a relative offset between meters (FG5X-233, FG5-220, FG5X-220) and the declared master meter (FG5-233) after applying the so-called degrees of equivalence (DoE) resulting from International Comparison Campaigns (henceforth ICC); monument ties (OSO has four observation points); and setup trend rate for each setup of the AG's. We refer to the following ICC's: Jiang et al. (2012), Francis et al. (2013), Francis et al. (2015), Pálinkáš et al. (2017) and Falk et al. (2020). For a review of the con-cept of DoE and their uncertainties, refer to Burns (2003) and any of the ICC publications. ...
... This leakage is principally at work at all the signals in regression and trades slope signal with the drift terms. However, uncertainty in the sum of these terms arises only (Jiang et al. 2012;Francis et al. 2013;Francis et al. 2015;Pálinkáš et al. 2017;Falk et al. 2020). The secular rate of − 3.53 nm/s 2 /year given in the diagram has an uncertainty of ± 0.32 nm/s 2 /year in the least-squares fit; the rate bias, however, adds ± 0.2 nm/s 2 /year to it in the case of signals that contain stochastic errors; that is, tides take no part in this. ...
Ten-year worth of absolute gravity (AG) campaigns at Onsala Space Observatory (OSO), Sweden, are simultaneously reduced using synchronous data from a superconducting gravimeter (SG). In this multi-campaign adjustment, the a priori models commonly applied for each setup in AG-alone experiments are sidestepped in favour of SG records and a model to estimate its drift. We obtain a residual (hourly samples) at the 5 nm/s RMS level, reducing the SG data with a range of ancillary data for the site’s exposure to ocean and atmospheric loading, and hydrology effects. The target quantity in AG projects in the Baltic Shield area is the secular change of gravity dominated by glacial isostatic adjustment with land uplift as its major part. Investigating into the details of the associated processes using AG requires a long-term stable reference, which is the aim of international comparison campaigns of FG5 instruments. Two of these have been campaigning at OSO since 2009 when the SG had been installed. In the simultaneous inversion of all sixteen campaigns, we identify weaknesses of AG observations, like varying systematic offsets over time, excess microseismic sensitivity, trends in the AG data and side effects on the SG’s scale factor when campaigns are evaluated one by one. The simultaneous adjustment afforded us an SG scale factor very near the result from a campaign with a prototype quantum gravimeter. Whence, we propose that single-campaign results may be biased and conjectures into their variation, let alone its causes misleading. The OSO site appears to present manageable problems as far as environmental influences are concerned. Our findings advocate the use of AG instruments and procedures that are more long-term stable (reference realization), more short-term stable too (setup drifts), less service craving and more resilient to microseismic noise.
... 59). Since then, the technology of atomic gravity sensors has considerably grown in maturity, as assessed by some major achievements, such as (i) the participation since 2009 to CIPM key comparisons (KC) and Euramet comparisons of absolute gravimeters, [60][61][62] in 2017, even if not included in the 3rd KC, 63 four atom gravimeters developed in China 39,64-66 have participated in the associated pilot study; ðiiÞ the demonstration of on board measurements, in a ship 67 and a plane; 68 and ðiiiÞ the industrial development and commercial product offer of atom gravimeters at a competitive level of performance. 69 In total, about 30 research groups and private companies are today working on the development of atomic gravity sensors. ...
The research on cold-atom interferometers gathers a large community of about 50 groups worldwide both in the academic and now in the industrial sectors. The interest in this sub-field of quantum sensing and metrology lies in the large panel of possible applications of cold-atom sensors for measuring inertial and gravitational signals with a high level of stability and accuracy. This review presents the evolution of the field over the last 30 years and focuses on the acceleration of the research effort in the last 10 years. The article describes the physics principle of cold-atom gravito-inertial sensors as well as the main parts of hardware and the expertise required when starting the design of such sensors. The author then reviews the progress in the development of instruments measuring gravitational and inertial signals, with a highlight on the limitations to the performances of the sensors, on their applications and on the latest directions of research.
... Il existe des campagnes de comparaison entre différents gravimètres absolus à atomes froids. Le gravimètre développé par le LNE-SYRTE par exemple participe à ces campagnes et a montré en 2013 une exactitude de 4, 9 × 10 −9 g [70]. Depuis, un piège dipolaire a été mis en place afin de travailler avec une source d'atomes ultra-froids, qui se disperse spatialement moins pendant la chute libre, ce qui diminue l'effet systématique venant de l'aberration du front d'onde [71]. ...
Ce manuscrit présente le développement expérimental d’un capteur inertiel à atomes froids mesurant l’accélération de pesanteur, la composante verticale du gradient de gravité et l’accélération horizontale, en choisissant des technologies qui permettent d’obtenir un capteur inertiel embarquable et hybridé avec des capteurs classiques. Le dispositif expérimental permet d’effectuer des séquences d’interférométrie verticales et horizontales avec des transitions Raman stimulées rétroréfléchies contra-propageantes. La séquence d’interférométrie à quatre impulsions Raman a été utilisée pour mesurer le gradient de gravité. Les effets systématiques ont été étudiées afin d’obtenir l’exactitude de la mesure. Notre mesure extrapolée avec une chute libre de 1 mètre et limitée par le bruit de projection quantique permettrait d’atteindre des sensibilités du même ordre que l’état de l’art. Cette méthode est intéressante pour un capteur embarquable car elle est facile à mettre en place, et elle est insensible à la force de Coriolis, qui cause une grosse chute de contraste pour un interféromètre Mach-Zehnder en dynamique. Cette méthode peut être utilisée pour la mesure de rotation dans un capteur inertiel embarqué. Une mesure de l’accélération horizontale a été effectuée en simple diffraction avec des faisceaux lasers Raman horizontaux contra-propageants et rétro-réfléchis. Pour la mesure de l'accélération horizontale, un interféromètre Mach-Zehnder horizontal a été utilisé. Une rampe de fréquence est appliquée sur les faisceaux Raman pour levée la dégénérescence des deux paires Raman. La mesure effectuée a une sensibilité proche de l'état de l'art.
... It has been regularly compared with other absolute gravimeters, especially during the three last key comparisons. 29,30 A 3D gravity map combined with a model of the gravitational field in the laboratories 31 allows one to transfer the absolute value of gravity at the center of mass of the watt balance mass artefact under test. Finally, the self-attraction effect of the watt balance itself is also taken into account using the methods developed for the calculation of the selfattraction effect of the CAG. ...
This paper describes the mechanical and electrical modifications carried out on the LNE watt balance to reduce the noise level associated with the static phase. The mechanical improvements concern the home-made balance beam using flexure hinges as pivots of the force comparator. The electrical improvements involve the source used to servo-control the equilibrium position of the beam during the static phase. All these modifications have led to a significant improvement of the repeatability and reproducibility of the results of static phase measurements.
... The resultant average velocity for the MN unit equals -0.3 mm/year for the northern component and 0.5 mm/year for the eastern component. For the PF unit, very similar residual velocities were also obtained, amounting to ±0.2-0.9 mm/year, along Table 5also take into account the results of calibration of absolute gravimeters presented as part of ICAG2011 (Francis at al., 2013), therefore the values of g are at a level which is in compliance with what is defined as the European level of reference. Comparing the results obtained using the ZZG and FG-5 gravimeters it can be concluded that the maximum discrepancies between the determinations reach up to 20µGal. ...
The Pieniny Klippen Belt (PKB), which is situated in Southern Poland, is one of the main fault zones on the boundary of the Outer and Inner Carpathians. The geodynamic investigations which have been carried out since 1960s indicate that PKB demonstrates neo-tectonic activity. In 1990s, the Dunajec river dam and the water reservoirs in Czorsztyn and Sromowce Wyzne have been built. This has created a new aspect in investigations related to the effect of tectonic movements on the dam. In 2001, after few years break, the investigations were revived. Current the measurements are performed annually, in the beginning of September and contain GNSS and gravimetric measurements. The results of horizontal displacement in the PKB area based on GNSS measurements as well as gravity changes obtained from absolute measurements in 2004-2015 are presented and discussed in this paper. © 2016, Academy of Sciences of the Czech Republic, All rights reserved.
... Intercomparison campaigns [e.g. Francis et al., 2005; 2010; 2013; 2015; Jiang et al., 2012; Schmerge et al., 2012; Vitushkin et al., 2002] showed that differences between FG5 and JILAg gravimeters are commonly of the order of 100-150 nm/s² . A difference as large as 461 nm/s² was reported for one of the A10 instruments that participated in the ICAG-2001 intercomparison [Vitushkin et al., 2002]. ...
... A difference as large as 461 nm/s² was reported for one of the A10 instruments that participated in the ICAG-2001 intercomparison [Vitushkin et al., 2002]. In other comparisons, systematic and random errors of A10 gravimeters ranged between 70 and 220 nm/s² [Jiang et al., 2011; Francis et al., 2005; 2013; 2015]. Concurrently, the uncertainty due to the setup of the AG instrument should be taken into account. ...
We estimate the signature of the climate-induced mass transfers in repeated absolute gravity measurements based on satellite gravimetric measurements from the GRACE mission. We show results at the globe scale, and compare them with repeated absolute gravity (AG) time behavior in three zones where AG surveys have been published: Northwestern Europe, Canada and Tibet. For 10 yearly campaigns, the uncertainties affecting the determination of a linear gravity rate of change range 3-4 nm/s²/a in most cases, in absence of instrumental artefacts. The results are consistent with what is observed for long term repeated campaigns. We also discuss the possible artefact that can results from using short AG survey to determine the tectonic effects in a zone of high hydrological variability. We call into question the tectonic interpretation of several gravity changes reported from stations in Tibet, in particular the variation observed prior to the 2015 Gorkha earthquake.
