Accurate Gravimetry at the BIPM Watt Balance Site

in Rizos, C.; Willis, P. (Eds.) Earth on the Edge: Science for a Sustanaible Planet (2014)

Measurement of the speed-of-light perturbation of free-fall absolute gravimeters

in Metrologia (2014), 51(3), 9

We report on a direct measurement of the relativistic Doppler shift with a commercial free-fall absolute gravimeter of the type FG5X. The observed Doppler shift, which is commonly called speed-of-light ... [more ▼]

We report on a direct measurement of the relativistic Doppler shift with a commercial free-fall absolute gravimeter of the type FG5X. The observed Doppler shift, which is commonly called speed-of-light perturbation, can be well described by the relativistic Doppler formula, where the constant object velocity is replaced by a time-dependent velocity with constant acceleration. The observed speed-of-light perturbation stands in contrast to other publications, which predict a higher frequency shift. It has been measured with a relative uncertainty of 1.1 × 10 −3 . [less ▲]

The European Comparison of Absolute Gravimeters 2011 (ECAG-2011) in Walferdange, Luxembourg: results and recommendations

in Metrologia (2013), 50(3), 257

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 ... [more ▼]

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 implemented. The gravity observations are also corrected for geophysical gravity changes that occurred during the comparison using the observations of a superconducting gravimeter. We show that these corrections improve the degree of equivalence between the gravimeters. We present the results for two different combinations of data. In the first one, we use only the observations from the metrological institutes. In the second solution, we include all the data from both metrological and non-metrological institutes. Those solutions are then compared with the official result of the comparison published previously and based on the observations of the metrological institutes and the gravity differences at the different sites as measured by non-metrological institutes. Overall, the absolute gravity meters agree with one another with a standard deviation of3.1 µ Gal. Finally, the results of this comparison are linked to previous ones. We conclude with some important recommendations for future comparisons. [less ▲]

On the evaluation of systematic effects in atom and corner-cube absolute gravimeters

in Physics Letters A (2012), 376

We show that due to analogy of atom and optical interferometry a perturbed phase propagates identically in atom and corner-cube absolute gravimeters. To evaluate associated systematic effects, we consider ... [more ▼]

We show that due to analogy of atom and optical interferometry a perturbed phase propagates identically in atom and corner-cube absolute gravimeters. To evaluate associated systematic effects, we consider both gravimeters as a linear system in the time domain. This formalism is based on a weighting function earlier derived for a corner-cube gravimeter. As an example, we demonstrate that the corrections for a linear change of gravity are essentially the same for both gravimeters. Application of a common formalism to analyse various systematic effects could reveal possible source of disagreement in comparisons of atom and corner-cube absolute gravimeters. [less ▲]

Relative Gravity Measurement Campaign during the 8th International Comparison of Absolute Gravimeters (2009)

in Metrologia (2012), 49(1), 95

The 8th International Comparison of Absolute Gravimeters (ICAG-2009) and the associated Relative Gravity Campaign (RGC2009) took place at the Bureau International des Poids et Mesures (BIPM) between July ... [more ▼]

The 8th International Comparison of Absolute Gravimeters (ICAG-2009) and the associated Relative Gravity Campaign (RGC2009) took place at the Bureau International des Poids et Mesures (BIPM) between July and October 2009. Altogether 24 institutes with 22 absolute gravimeters and 9 relative gravimeters participated in the ICAG/RGC campaign. Accurate absolute and relative gravity measurements as well as precision levelling measurements were performed on the micro-gravity 3D-grid at the BIPM. The 2009 comparison was the first to be organized as a Comité International des Poids et Mesures (CIPM) metrological Key Comparison under the CIPM MRA (Mutual Recognition Arrangement), which means that the result will be officially recognized by the governmental organizations responsible. As a consequence, the relative gravimeters employed were carefully selected and the measurement schedules were rigorously enforced compared with earlier campaigns. Thus the quality of the RGC2009 and the determination of the BIPM local gravity network were improved. After 30 years and eight successive ICAGs, the BIPM has decided to transfer its role to the national metrological institutes, although the CIPM will continue to organize the key comparison as ICAGs. The background to the RGC2009, and the organization, data processing and final results of the gravity and vertical gravity gradients, are presented in this paper. This report is more detailed than previous final reports of the RGCs. [less ▲]

Preliminary results of the BIPM Relative Gravity Measurement Campaign during the 8th International Comparison of Absolute Gravimeters (2009)

in Peshekhonov, Vladimir (Ed.) Proceedings of the IAG Symposium on Terrestrial Gravimetry: Static and Mobile Measurements (2011)

Reply to "Comment on second-order Doppler-shift corrections in free-fall absolute gravimeters"

in Metrologia (2011), 48

Results of the European Comparison of Absolute Gravimeters in Walferdange (Luxembourg) of November 2007

in Gravity, Geoid and Earth Observation (2010)

The second international comparison of absolute gravimeters was held in Walferdange, Grand Duchy of Luxembourg, in November 2007, in which twenty absolute gravimeters took part. A short description of the ... [more ▼]

The second international comparison of absolute gravimeters was held in Walferdange, Grand Duchy of Luxembourg, in November 2007, in which twenty absolute gravimeters took part. A short description of the data processing and adjustments will be presented here and will be followed by the presentation of the results. Two different methods were applied to estimate the relative offsets between the gravimeters. We show that the results are equivalent as the uncertainties of both adjustments overlap. The absolute gravity meters agree with one another with a standard deviation of 2 μgal (1 gal = 1 cm/s2). [less ▲]

First Experience with the Transportable MPG-2 Absolute Gravimeter

in Mertikas, Stelios P. (Ed.) Gravity, Geoid and Earth Observation (2010)

We report on design details and first results obtained with the transportable absolute gravimeter MPG-2 (“Max-Planck-Gravimeter”). It is developed as an evolution of the stationary device MPG-1, completed ... [more ▼]

We report on design details and first results obtained with the transportable absolute gravimeter MPG-2 (“Max-Planck-Gravimeter”). It is developed as an evolution of the stationary device MPG-1, completed in 2007. The MPG-2 is built on a common scheme where the position of a freely falling object is monitored. The setup consists of a ballistic block, an interferometer and the electronics. Free fall drops can be repeated every 10 s with the standard deviation close to 30 μgal. A one-day gravity observation gives a result with a standard deviation of the mean of less than 5 μgal. A prototype of the MPG-2 took part in the ECAG-2007. New measurements at the reference gravity station “Bad Homburg”, Germany confirmed the declared combined standard uncertainty of 50 μgal. [less ▲]

Development of new free-fall absolute gravimeters

in Metrologia (2009), 46(3), 283-297

The design and first results of two free-fall absolute gravimeters are reported: a stationary gravimeter is designed and can be used as a reference system and a portable gravimeter is aimed at field ... [more ▼]

The design and first results of two free-fall absolute gravimeters are reported: a stationary gravimeter is designed and can be used as a reference system and a portable gravimeter is aimed at field measurements. The determination of the acceleration due to gravity is done interferometrically in both instruments. The whole fringe signal is digitized by a high-speed analogue-to-digital converter, which is locked to a rubidium frequency standard. This fringe recording and processing is novel as compared with commercial free-fall gravimeters, which use an electronic zero-crossing discrimination. Advantages such as the application of a zero-phase-shifting digital filter to the digitized data are depicted. The portable gravimeter's mechanics deviate from the conventional type. Springs are used to accelerate and decelerate the carriage supporting the falling object. A detailed uncertainty budget is given for both gravimeters. The combined standard uncertainty for the portable and for the stationary gravimeter is estimated at 38.8 µGal and 16.6 µGal, respectively. The corresponding statistical uncertainties are 1.6 µGal (over one day of measurement) and 0.6 µGal (over one month of measurement). The different designs and dimensions of the new free-fall gravimeters can help to reveal unknown or so far underestimated systematic effects. The assessments of the uncertainties due to seismic noise and shock vibrations, and electronic phase shifts give validity to this assumption. [less ▲]