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Gravimeter
About: Gravimeter is a research topic. Over the lifetime, 2380 publications have been published within this topic receiving 30359 citations.
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TL;DR: In this article, an atom interferometer based on a fountain of laser-cooled atoms was used to measure the acceleration of gravity, achieving an absolute uncertainty of Δg/g ≈ 3 × 10−9.
Abstract: Laser-cooling of atoms and atom-trapping are finding increasing application in many areas of science1 One important use of laser-cooled atoms is in atom interferometers2 In these devices, an atom is placed into a superposition of two or more spatially separated atomic states; these states are each described by a quantum-mechanical phase term, which will interfere with one another if they are brought back together at a later time Atom interferometers have been shown to be very precise inertial sensors for acceleration3,4, rotation5 and for the measurement of the fine structure constant6 Here we use an atom interferometer based on a fountain of laser-cooled atoms to measure g, the acceleration of gravity Through detailed investigation and elimination of systematic effects that may affect the accuracy ofthe measurement, we achieve an absolute uncertainty of Δg/g ≈ 3 × 10−9, representing a million-fold increase in absoluteaccuracy compared with previous atom-interferometer experiments7 We also compare our measurement with the value of g obtained at the same laboratory site using a Michelson interferometer gravimeter (a modern equivalent of Galileo's ‘leaning tower’ experiment in Pisa) We show that the macroscopic glass object used in this instrument falls with the same acceleration, to within 7 parts in 109, as a quantum-mechanical caesium atom
803 citations
TL;DR: The design improvements incorporated in a new generation of absolute gravimeters, the FG5, have led to an instrumental uncertainty estimate of 1,1 × 10-8 m s-2 (1,0 μGal).
Abstract: We describe the design improvements incorporated in a new generation of absolute gravimeters, the FG5. A vertically oriented (in-line) interferometer design is used to remove the influence of floor vibration and tilt on the optical path length. The interferometer uses an iodine-stabilized laser as a primary length standard, with circuitry for automatic peak detection and locking. The seismic isolation system is an active long-period seismometer (Super Spring). The new design has improved passive isolation and thermal drift characteristics over previous systems. Programming flexibility and control of the test mass trajectory have been improved. The computer system has also improved real-time analysis and system capability. The FG5 instrument has a higher level of robustness, reliability and ease of use. These design advances have led to an instrumental uncertainty estimate of 1,1 × 10-8 m s-2 (1,0 μGal). Instrument agreement among nine similar devices is 1,8 μGal and observations under optimal conditions exhibit standard deviations of 5 μGal to 8 μGal.
496 citations
TL;DR: In this paper, an improved scheme to drive the stimulated Raman transitions was used to achieve a resolution of 3×10−8 g after 2×103 seconds of integration time.
Abstract: Velocity sensitive stimulated Raman transitions have been used to measure the gravitational acceleration, g, of laser cooled sodium atoms in an atomic fountain geometry. By using an improved scheme to drive the Raman transitions, we have demonstrated a resolution of 3×10−8 g after 2×103 seconds of integration time. In addition to presenting recent experimental results, we review the theory of stimulated Raman transitions as it applies to atom interferometers and discuss the prospects of an atom interferometer-based gravimeter with better than 10−10 g absolute accuracy.
426 citations
TL;DR: In this paper, the authors considered the correction for the gravitational attraction of the topography on a gravity station is considered as consisting of two parts; (1) the restricted but conventional Bouguer correction, which postulates as a convenient approximation that the terrain consists of an infinite horizontal plain, and (2) the "Terrain correction" which is a supplementary correction taking into account the gravitational effect of the undulations of the terrain about the plane through the gravity station.
Abstract: In this paper the correction for the gravitational attraction of the topography on a gravity station is considered as consisting of two parts; (1) the restricted but conventional "Bouguer correction" which postulates as a convenient approximation that the topography consists of an infinite horizontal plain, and (2) the "Terrain correction" which is a supplementary correction taking into account the gravitational effect of the undulations of the terrain about the plane through the gravity station. The paper illustrates the necessity of making terrain corrections if precise gravity surveys are desired in hilly country and presents terrain correction tables with which this quantity may be determined to a relative accuracy of one-tenth milligal. This accuracy is required to fully utilize the high instrumental precision of modern gravimeters.
392 citations
TL;DR: In this paper, a gravimeter is constructed which uses the near perfect stability of superconducting persistent currents to make it a device with exceptional stability, and it is used to measure changes in the vertical position of the sphere or as changes in a feedback force, independent of the primary supporting force, which holds the sphere in a fixed position.
Abstract: A gravimeter is constructed which uses the near perfect stability of superconducting persistent currents to make it a device with exceptional stability. A superconducting sphere is levitated in the magnetic field generated by two superconducting coils. Changes in gravitational or inertial forces in the vertical direction are measured as changes in the vertical position of the sphere or as changes in a feedback force, independent of the primary supporting force, which holds the sphere in a fixed position. In its present state of development the instrument produces data which, when compared to calculated earth tides, set an upper limit on the drift rate of ±6 parts in 109 of g/day. Several possible sources of drift are discussed.
266 citations