Laboratoire commun de métrologie

Abstract Measuring gravity from an aircraft or a ship is essential in geodesy, geophysics, mineral and hydrocarbon exploration, and navigation. Today, only relative sensors are available for onboard gravimetry. This is a major drawback because of the calibration and drift estimation procedures which lead to important operational constraints. Atom interferometry is a promising technology to obtain onboard absolute gravimeter. But, despite high performances obtained in static condition, no precise measurements were reported in dynamic. Here, we present absolute gravity measurements from a ship with a sensor based on atom interferometry. Despite rough sea conditions, we obtained precision below 10 −5 m s −2 . The atom gravimeter was also compared with a commercial spring gravimeter and showed better performances. This demonstration opens the way to the next generation of inertial sensors (accelerometer, gyroscope) based on atom interferometry which should provide high-precision absolute measurements from a moving platform.

We review the principles, techniques and results from primary acoustic gas thermometry (AGT). Since the establishment of ITS-90, the International Temperature Scale of 1990, spherical and quasi-spherical cavity resonators have been used to realize primary AGT in the temperature range 7 K to 552 K. Throughout the sub-range 90 K < T < 384 K, at least two laboratories measured ( T − T 90 ). (Here T is the thermodynamic temperature and T 90 is the temperature on ITS-90.) With a minor exception, the resulting values of ( T − T 90 ) are mutually consistent within 3 × 10 −6 T . These consistent measurements were obtained using helium and argon as thermometric gases inside cavities that had radii ranging from 40 mm to 90 mm and that had walls made of copper or aluminium or stainless steel. The AGT values of ( T − T 90 ) fall on a smooth curve that is outside ± u ( T 90 ), the estimated uncertainty of T 90 . Thus, the AGT results imply that ITS-90 has errors that could be reduced in a future temperature scale. Recently developed techniques imply that low-uncertainty AGT can be realized at temperatures up to 1350 K or higher and also at temperatures in the liquid-helium range.

We report a new experimental scheme which combines atom interferometry with Bloch oscillations to provide a new measurement of the ratio $h/{m}_{\mathrm{Rb}}$. By using Bloch oscillations, we impart to the atoms up to 1600 recoil momenta and thus we improve the accuracy on the recoil velocity measurement. The deduced value of $h/{m}_{\mathrm{Rb}}$ leads to a new determination of the fine structure constant ${\ensuremath{\alpha}}^{\ensuremath{-}1}=137.035\text{ }999\text{ }45\text{ }(62)$ with a relative uncertainty of $4.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$. The comparison of this result with the value deduced from the measurement of the electron anomaly provides the most stringent test of QED.

We used a quasi-spherical cavity as an acoustic and microwave resonator to measure the thermodynamic temperatures, T, of the triple points of equilibrium hydrogen, neon, argon and mercury and to measure the difference T − T90, in the range 7 K to 273 K. (T90 is the temperature on the International Temperature Scale of 1990 (ITS-90).) In the range 7 K to 24.5 K, our preliminary values of T − T90 agree with recent results from dielectric-constant gas thermometry and achieve uncertainties that are comparable to or smaller than those achievable using the interpolating constant volume gas thermometer as currently defined on the ITS-90. In the range 90 K to 273 K, the present results for T − T90 obtained using a helium-filled, copper-walled, quasi-spherical cavity agree with earlier results obtained using argon-filled, steel-walled or aluminium-walled, spherical cavities. The agreement confirms our understanding of both acoustic and microwave cavity resonators and demonstrates that resonators function as primary thermometers spanning wide temperature ranges. The mutually consistent acoustic thermometry data from several laboratories imply that the values of (T − T90)/T90 are 5 times larger than the uncertainty of T/T90 near 150 K and near 400 K. They also imply that the derivative dT/dT90 is too large by approximately 10−4 near 273.16 K and that dT/dT90 has a discontinuity of 4 × 10−5 at 273.16 K.

Measuring gravity from an aircraft is essential in geodesy, geophysics and exploration. It fills a gap between satellite techniques which have a low spatial resolution and traditional ground measurements which can only be performed on ground in accessible areas. Today, only relative sensors are available for airborne gravimetry. This is a major drawback because of the calibration and drift estimation procedures which lead to important operational constraints and measurement errors. Here, we report an absolute airborne gravimeter based on atom interferometry. This instrument has been first tested on a motion simulator leading to gravity measurements noise of 0.3 mGal for 75 s filtering time constant. Then, we realized an airborne campaign across Iceland in April 2017. From repeated line and crossing points, we obtain gravity measurements with an estimated error between 1.7 and 3.9 mGal. The airborne measurements have also been compared to upward continued ground gravity data and show differences with a standard deviation ranging from 3.3 to 6.2 mGal and a mean value ranging from − 0.7 to − 1.9 mGal.

Intra‐tooth sequential analysis of enamel δ 18 O is currently used to investigate birth seasonality in past animal populations, offering new insights into seasonal availability of animal resources, herd management and seasonality of site occupation. Reference data sets are still required to address two major difficulties: (1) that inter‐individual variability in the record of the seasonal cycle is affected by tooth size; and (2) that the season of birth cannot be directly estimated from the timing of tooth growth, because of a delay in enamel mineralization. We present a data set acquired on the lower second molar of 10 modern sheep from Rousay (Orkney) born within a few weeks of each other in April/May and submitted to the same environmental conditions until death. All sheep have recorded a sinusoidal pattern of δ 18 O variation spanning approximately a year. From the difference between the expected and the measured time sequence, the delay of enamel mineralization is estimated to be 5–6 months. The data set is then described using a model mainly based on a cosine function. The period, corresponding to the length of the M2 crown formed over a year, averaged 35.8 mm. A very slight variation of tooth growth rate with time and no attenuation of the isotopic signal towards the cervical margin of the crown could be detected in this data set. The lowest δ 18 O values, corresponding to the sheep's first winter, were tracked at a distance from the enamel/root junction that varied between 23.0 and 30.3 mm (x min mean = 27.6 mm); the highest δ 18 O values, corresponding to the sheep's second summer, were between 6.3 and 11.6 mm (x max mean = 9.9 mm). Most of the variability can be attributed to tooth size. When normalized on the period, x min and x max are 0.28 ( ± 0.05) and 0.78 ( ± 0.05) on average, meaning that the Rousay sheep have recorded the minimum and maximum δ 18 O values on average at 78% and 28%, respectively, of the end of the periodic cycle recorded in the second molar.

The paper presents a comprehensive overview of existing data for the evaluation of spoken content processing in a multimedia framework for the French language.We focus on the ETAPE corpus which will be made publicly available by ELDA at the end of 2012, after completion of the evaluation, and recall existing resources resulting from previous evaluation campaigns.The ETAPE corpus consists of 30 hours of TV and radio broadcasts, selected to cover a wide variety of topics and speaking styles, emphasizing spontaneous speech and multiple speaker areas.

Étude, par la diffraction des rayons X, des transformations d'un monocristal de solution solide sursaturée avant et pendant la précipitation de la nouvelle phase. Les irrégularités du réseau sont révélées par des diffusions anormales en dehors des directions de réflexion sélective. Les atomes dissous . se rassemblent d'abord en noyaux où ils tendent à s'ordonner avec les atomes d'aluminium : puis le réseau se transforme. Comparaison des stades intermédiaires dans le cas des alliages au cuivre et à l'argent.

A new Watt balance project is now in progress at the Bureau National de Metrologie (BNM), Paris, France. In this paper, the general configuration and the main parts of the experimental setup currently in development are presented. The aim is to contribute to the international effort in monitoring the kilogram toward a new definition of the mass unit with a relative accuracy of 10/sup -8/ or better.

There is currently great interest in the international metrological community for new accurate determinations of the Boltzmann constant k B, with the prospect of a new definition of the unit of thermodynamic temperature, the kelvin. In fact, k B relates the unit of energy (the joule) to the unit of the thermodynamic temperature (the kelvin). One of the most accurate ways to access the value of the Boltzmann constant is from measurements of the velocity of the sound in a noble gas. In the method described here, the experimental determination has been performed in a closed quasi-spherical cavity. To improve the accuracy, all the parameters in the experiment (purity of the gas, static pressure, temperature, exact shape of the cavity monitored by EM microwaves, etc.) have to be carefully controlled. Correction terms have been computed using carefully validated theoretical models, and applied to the acoustic and microwave signals. We report on two sets of isothermal acoustic measurements yielding the value k B = 1.380 647 74(171) × 10−23 J · K−1 with a relative standard uncertainty of 1.24 parts in 106. This value lies 1.9 parts in 106 below the 2006 CODATA value (Mohr et al., Rev. Mod. Phys. 80, 633 (2008)), but, according to the uncertainties, remains consistent with it.

The chalcopyrite crystal LiGaTe 2 was grown by the Bridgman-Stockbarger technique with sufficient size and optical quality that allowed the characterization of its linear (dispersion and birefringence) and nonlinear optical properties. X-ray structural analysis was performed on single crystals. The transmission was recorded in the 0.5−24 μm range, and Raman and IR-spectra were recorded in the 0−400 cm -1 and 180−400 cm -1 ranges, respectively. The clear transparency range of LiGaTe 2 extends from 2.5 to 12 μm, the band-gap at room temperature is at 2.41 eV (515 nm), residual absorption limits the transmission near the band-edge, and the upper limit for the transmission is determined by the onset two-phonon absorption. LiGaTe 2 is a positive uniaxial crystal that possesses sufficient birefringence for phase-matching. Its nonlinear coefficient d 36 was estimated by phase-matched second harmonic generation to be 43 pm/V ± 10%. It is only the third crystal belonging to the A I B III chalcopyrite family for which phase-matched nonlinear frequency conversion could be demonstrated, and of this group it exhibits the highest nonlinearity and figure of merit for nonlinear optical applications in the mid-infrared.

Lithium selenoindate (LiInSe2) is a new nonlinear chalcogenide biaxial crystal, related to LiInS2 and transparent from 0.54 to 10&#x2009;&#x3bc;m at the 50% level (10 mm thickness), which has been successfully grown in large sizes and with good optical quality. We report on what we believe to be new physical properties that are relevant for laser and nonlinear optical applications and summarize all relevant characteristics, both from the literature and as measured in the present work. With respect to AgGaS(e)2 ternary chalcopyrite materials, LiInSe2 displays a nearly isotropic thermal expansion behavior with three- to five-times-larger thermal conductivities associated with high optical damage thresholds, and low intensity-dependent absorption, allowing direct high-power downconversion from the near-infrared, especially 1064 nm, to the deep mid-infrared. Continuous-wave difference-frequency generation (5.9&#x2013;8.1&#x2009;&#x3bc;m) of Ti:sapphire laser sources is reported for the first time as well as nanosecond optical parametric oscillation with a Nd:YAG laser as the pump source at 100 Hz and idler tuning between 4.7 and 8.7&#x2009;&#x3bc;m.

Abstract A determination of the Planck constant h using the LNE Kibble balance in air was carried out in the spring of 2017. Substantial improvements since 2014, chiefly related to the mass standard, mechanical alignments, voltage measurements and type A evaluation uncertainties, leads to a h value of 6.626 070 41(38) × 10 –34 J · s, with a relative standard uncertainty of 5.7 × 10 –8 .

The thermodynamic temperature of the point of inflection of the melting transition of Re-C, Pt-C and Co-C eutectics has been determined to be 2747.84 ± 0.35 K, 2011.43 ± 0.18 K and 1597.39 ± 0.13 K, respectively, and the thermodynamic temperature of the freezing transition of Cu has been determined to be 1357.80 ± 0.08 K, where the ± symbol represents 95% coverage. These results are the best consensus estimates obtained from measurements made using various spectroradiometric primary thermometry techniques by nine different national metrology institutes. The good agreement between the institutes suggests that spectroradiometric thermometry techniques are sufficiently mature (at least in those institutes) to allow the direct realization of thermodynamic temperature above 1234 K (rather than the use of a temperature scale) and that metal-carbon eutectics can be used as high-temperature fixed points for thermodynamic temperature dissemination. The results directly support the developing mise en pratique for the definition of the kelvin to include direct measurement of thermodynamic temperature.

We have measured the Rydberg constant by frequency comparison of the three transitions 2${\mathit{S}}_{1/2\mathrm{\ensuremath{-}}}$8${\mathit{S}}_{1/2}$, 2${\mathit{S}}_{1/2\mathrm{\ensuremath{-}}}$8${\mathit{D}}_{3/2}$, and 2${\mathit{S}}_{1/2\mathrm{\ensuremath{-}}}$8${\mathit{D}}_{5/2}$ in hydrogen with the difference of two optical standards, the methane-stabilized He-Ne laser and the iodine-stabilized He-Ne laser. The frequency of the iodine-stabilized He-Ne laser has been remeasured. The new value for the Rydberg constant, ${\mathit{R}}_{\mathrm{\ensuremath{\infty}}}$=109 737.315 683 0(31) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$, is currently the most precise available.

Output power as high as 790 mW are achieved starting from 370 mW at 1319 nm and 770 mW at 1064 nm, corresponding to

The SI unit of temperature will soon be redefined in terms of a fixed value of the Boltzmann constant k derived from an ensemble of measurements worldwide. We report on a new determination of k using acoustic thermometry of helium-4 gas in a 3 l volume quasi-spherical resonator. The method is based on the accurate determination of acoustic and microwave resonances to measure the speed of sound at different pressures. We find for the universal gas constant R = 8.314 4614(50) J·mol −1 ·K −1 . Using the current best available value of the Avogadro constant, we obtain k = 1.380 648 78(83) × 10 −23 J·K −1 with u ( k )/ k = 0.60 × 10 −6 , where the uncertainty u is one standard uncertainty corresponding to a 68% confidence level. This value is consistent with our previous determinations and with that of the 2014 CODATA adjustment of the fundamental constants (Mohr et al 2016 Rev. Mod. Phys . 88 035009), within the standard uncertainties. We combined the present values of k and u ( k ) with earlier values that were measured at LNE. Assuming the maximum possible correlations between the measurements, ( k present /〈 k 〉 − 1) = 0.07 × 10 −6 and the combined u r ( k ) is reduced to 0.56 × 10 −6 . Assuming minimum correlations, ( k present /〈 k 〉 − 1) = 0.10 × 10 −6 and the combined u r ( k ) is reduced to 0.48 × 10 −6 .

The principles and techniques of primary refractive-index gas thermometry (RIGT) are reviewed. Absolute primary RIGT using microwave measurements of helium-filled quasi-spherical resonators has been implemented at the temperatures of the triple points of neon, oxygen, argon and water, with relative standard uncertainties ranging from 9.1 × 10 −6 to 3.5 × 10 −5 . Researchers are now also using argon-filled cylindrical microwave resonators for RIGT near ambient temperature, with relative standard uncertainties between 3.8 × 10 −5 and 4.6 × 10 −5 , and conducting relative RIGT measurements on isobars at low temperatures. RIGT at optical frequencies is progressing, and has been used to perform a Boltzmann constant measurement at room temperature with a relative standard uncertainty of 1.2 × 10 −5 . Uncertainty budgets from implementations of absolute primary microwave RIGT, relative primary microwave RIGT and absolute primary optical RIGT are provided.

The ETAPE evaluation is the third evaluation in automatic speech recognition and associated technologies in a series which started with ESTER.This evaluation proposed some new challenges, by proposing TV and radio shows with prepared and spontaneous speech, annotation and evaluation of overlapping speech, a cross-show condition in speaker diarization, and new, complex but very informative named entities in the information extraction task.This paper presents the whole campaign, including the data annotated, the metrics used and the anonymized system results.All the data created in the evaluation, hopefully including system outputs, will be distributed through the ELRA catalogue in the future.

Abstract The most straightforward way to assess the glossiness of a surface is by measuring the specular reflectance by use of a specular glossmeter. Although alternative measurement methods have been proposed, this is still the most frequently used instrumental measurement technique for gloss evaluation until today. However, due to both the multidimensional nature of gloss perception and to the initial purpose of a specular glossmeter only to judge the gloss differences of surfaces with similar appearance, specular glossmeter results do not seem to provide a reliable basis for estimating the gloss appearance of a surface. During the past decades, increased attention has been paid to understanding how the human visual system arrives at a particular sensation of surface gloss, and which factors influence this process. This article was established in response to these new insights, and provides the reader an overview of the most important developments and findings regarding gloss measurement and gloss perception over the past 15 years. With the ultimate goal to achieve a better correspondence between gloss measurement and gloss perception in the future, issues of alternative measurement methods are considered, and some suggestions for relevant future research are proposed. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 559–570, 2014