Pierre Gillot

Tyrrhenian Sea tephrochronology of the oxygen isotope record for the past 60,000 years

Abstract A chronology of the marine oxygen isotope record of the past 60 ka is proposed by correlating eight marine ash-layers with terrestrial volcanic deposits, dated by the 14C and/or K Ar methods. Detailed oxygen isotope analyses were made on the planktonic foraminifera of three cores collected in the central Tyrrhenian Sea. The origin of the ash-layers was determined by major and trace elements analyses. Then the major pyroclastic terrestrial deposits were sampled, and analysed in order to provide land-sea correlations. Two ash-layers occurred during the warm event that followed the first step of the deglaciation, and which was dated at 12.6±0.5 ka B.P. Another ash-layer is present near the last glacial maximum that we have dated at 17.5±0.3 ka B.P. During isotopic stage 3, five ash-layers were recognized and dated, which allowed us to assign ages to the isotopically light oxygen peaks (warmer interstadials) at 31±1.5 ka and 33.4±1.6 ka (Denekamp), at 37.5±2 ka (Hengelo), and successively at 49±2 ka, 52.4±2.2 ka, 57±2.2 ka and 60.5±2.2 ka (Moershoofd complex).

Stability comparison of two absolute gravimeters: optical versus atomic interferometers

We report the direct comparison between the stabilities of two mobile absolute gravimeters of different technology: the LNE-SYRTE Cold Atom Gravimeter and FG5X#216 of the Universite du Luxembourg. These instruments rely on two different principles of operation: atomic and optical interferometry. The comparison took place in the Walferdange Underground Laboratory for Geodynamics in Luxembourg, at the beginning of the last International Comparison of Absolute Gravimeters, ICAG-2013. We analyse a 2h10 duration common measurement, and find that the CAG shows better immunity with respect to changes in the level of vibration noise, as well as a slightly better short term stability.

CCM.G-K2 key comparison

In November 2013 an International Key Comparison, CCM.G-K2, was organized in the Underground Laboratory for Geodynamics in Walferdange. The comparison has assembled 25 participants coming from 19 countries and four different continents. The comparison was divided into two parts: the key comparison that included 10 NMIs or DIs, and the pilot study including all participants. The global result given by the pilot study confirms that all instruments are absolutely coherent to each other. The results obtained for the key comparison confirm a good agreement between the NMI instruments. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Metrology with Atom Interferometry: Inertial Sensors from Laboratory to Field Applications

Developments in atom interferometry have led to atomic inertial sensors with extremely high sensitivity. Their performances are for the moment limited by the ground vibrations, the impact of which is exacerbated by the sequential operation, resulting in aliasing and dead time. We discuss several experiments performed at LNE-SYRTE in order to reduce these problems and achieve the intrinsic limit of atomic inertial sensors. These techniques have resulted in transportable and high-performance instruments that participate in gravity measurements, and pave the way to applications in inertial navigation.

Influence of chirping the Raman lasers in an atom gravimeter: phase shifts due to the Raman light shift and to the finite speed of light

We present here an analysis of the influence of the frequency dependence of the Raman laser light shifts on the phase of a Raman-type atom gravimeter. Frequency chirps are applied to the Raman lasers in order to compensate gravity and ensure the resonance of the Raman pulses during the interferometer. We show that the change in the Raman light shift when this chirp is applied only to one of the two Raman lasers is enough to bias the gravity measurement by a fraction of

Effective velocity distribution in an atom gravimeter: effect of the convolution with the response of the detection

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Magma genesis controlled by tectonic styles in the northern part of the Arabia plate during Cenozoic time

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Morpho-structural analysis of Harrat Al Sham volcanic field Arabian plate (Syria, Jordan, and Saudi Arabia): methodology and application

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Coherent population trapping in a Raman atom interferometer

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Continuous free fall acceleration determination for the LNE Watt balance

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