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Frequency standard using an atomic fountain of optically trapped atoms . United States Patent 5338930 . Abstract: Beams of laser light trap and cool cesium atoms in a small vapor cell and put the atoms in a particular quantum mechanical state. The lasers are then configured so as to launch the atoms upward by shifting the frequencies of the ...

the caesium frequency is made using the weighted mean of all the fountains. (Some figures in this article are in colour only in the electronic version) 1. Introduction The first formal evaluation of a caesium fountain primary frequency standard (PFS) was reported to the Bureau International des Poids et Measures (BIPM) by the

fountain frequency standard Metrologia 48 87–100 [2] Li R and Gibble K 2004 Phase variations in microwave. cavities for atomic clocks Metrologia 41 376–86 [3] ...

The fractional frequency stability, limited predominantly by noise in the local oscillator, is measured to be 7 × 10 -16 after one day of averaging. Based on the proposed quasi-continuous regime of operation of the fountain, the accuracy of the Rb standard of 5 × 10 -17 reachable in …

The fractional frequency uncertainties of some Cs fountains are now in the range of 4 × 10−16 to 5 × 10−16. The results of this investigation show that the standards agree well with each other. An overall estimate of the caesium frequency is made using the weighted mean of all the fountains.

The NIST-F2 caesium fountain clock operated by the National Institute of Standards and Technology (NIST) was officially launched in April 2014, to serve as a new U.S. civilian frequency and time standard, along with the NIST-F1 standard. The planned u B performance level of NIST-F2 is 1 × 10 −16. " At this planned performance level the NIST-F2 clock will not lose a second in at least 300 ...

atomic fountain frequency standard Jocelyne Gu ena, Gregor Dudle, Pierre Thomann To cite this version: Jocelyne Gu ena, Gregor Dudle, Pierre Thomann. An experimental study of intermodulation e ects in an atomic fountain frequency standard. European Physical Journal: Applied Physics, EDP Sciences, 2007, pp.183-189. <10.1051/epjap:2007072>.

and evaluation procedures for NIST-F1, a Cs fountain primary frequency standard operated by the NIST Time and Frequency Division [1], [2]. NIST-F1 joins the fountain of the Laboratoire Primaire du Temps et des Fréquences (LPTF) [3] as a primary standard based on …

in an atomic fountain frequency standard J. Guéna 1, G. Dudle, P. Thomann 2 METAS, Lindenweg 50, 3003 Bern-Wabern, Switzerland 1 1 On leave from Laboratoire Kastler Brossel, CNRS UMR 8552, 24 Rue Lhomond, F-75231 Paris Cedex 05, France

This enables frequency measurement precision equivalent to less than 1 part in 10 13 for one second of averaging time. The long-term accuracy of this fountain standard is at parts in 10 16, limited by uncertainty of systematic frequency shifts, such as perturbations …

A post-processed time scale, involving an ensemble of five hydrogen masers, has been developed by a NIST scientist in Boulder to serve as a reference for comparing primary frequency standards.During the last 2 years, this time scale has been used to evaluate the relative frequencies of NIST-7, an optically pumped cesium-beam standard, and NIST-F1, the cesium-fountain frequency standard.

A caesium atomic fountain used as part of an atomic clock. The caesium standard is a primary frequency standard in which the photon absorption by transitions between the two hyperfine ground states of caesium-133 atoms are used to control the output frequency. The first caesium clock was built by Louis Essen in 1955 at the National Physical ...

The first cesium atomic fountain (India-CsF1) frequency standard is now completely assembled and operational. The CsF1 fountain has a (0, 0, 1) geometry of the magneto-optical trap (MOT) for cooling and launching operations. In this geometry, four out of the six cooling beams are in horizontal plane and other are going up and down, respectively.

The fountains intercompared are the primary frequency standards (PFS) FO1, FO2 located at SYRTE and CSF1, CSF2 [19, 20] located at PTB. FO2 is a dual fountain operating simultaneously with caesium and rubidium atoms, known as FO2-Cs (PFS) and FO2-Rb (secondary frequency standard realizing the 87 Rb

The Primary Time and Frequency Standard for the United States. NIST-F1, the nation's primary time and frequency standard, is a cesium fountain atomic clock developed at the NIST laboratories in Boulder, Colorado. NIST-F1 contributes to the international group of atomic clocks that define Coordinated Universal Time (UTC), the official world time.

National Physical Laboratory India has developed a cesium atomic fountain frequency standard. The fountain has now become operational and is ready for complete frequency evaluation. In this paper, we report for the first time, the preliminary results obtained with this fountain, which include Ramsey fringes, frequency stability analysis, with an H-maser, and magnetic field mapping in the ...

NIM5-M is a new generation of laser cooling-cesium atomic fountain frequency-standard developed by NIM (National Institute of Metrology, China). In this paper, thorough research on the engineering applications of NIM5-M is conducted. The continuous automatic operation of NIM5-M is achieved. And a software is implemented to realize automatic ...

Design and metrological features of microwave synthesizers for atomic fountain frequency standard. IEEE Transactions on Ultrasonics, Ferroelectrics and …

This response is then used to calculate the degradation of the frequency stability of a pulsed atomic frequency standard such as an atomic fountain or an ion trap standard. Comparison is made to an experimental evaluation of this effect in the LPTF Cs fountain …

The cesium fountain clock as primary frequency standard is widely used in the areas, such as time-keeping system, satellite navigation, fundamental physics research, etc. The principle of operation of cesium fountain clock is introduced. The noise source and frequency shift term are ananlyzed. The major noise source influencing frequency stability are cold atom loading time, …

A frequency standard is a stable oscillator used for frequency calibration or reference. A frequency standard generates a fundamental frequency with a high degree of accuracy and precision.Harmonics of this fundamental frequency are used to provide reference points. Since time is the reciprocal of frequency, it is relatively easy to derive a time standard from a frequency standard.

We report on the first comparison of distant caesium fountain primary frequency standards (PFSs) via an optical fiber link. The 1415 km long optical link connects two PFSs at LNE-SYRTE (Laboratoire National de métrologie et d'Essais - SYstème de Références Temps-Espace) in Paris (France) with two at PTB (Physikalisch-Technische Bundesanstalt) in Braunschweig (Germany). …

Leaders of the G20 throw coins into the Trevi Fountain during a walk through Rome, where they have gathered for a two-day summit.Continue reading: https://ww...

A frequency standard based on an atomic fountain of cesium atoms may have an accuracy of 10(exp -16) due to longer interaction times and smaller anticipated systematic errors. All of the known systematic effects that now limit the accuracy of the Cs frequency standard increase either linearly or as some higher power of the atom's velocity. The one systematic frequency shift which is ...

The definition of SI second can be realized in practice by primary Cs atomic frequency standard (PFS). Cs fountain clocks are not commercially available and have been indigenously developed in less than ten countries worldwide. [1,2,3,4,5,6,7,8,9]. India's first Cs fountain (NPLI-CsF1) was successfully developed at CSIR-NPL [10, 11]. NPLI ...

A systems approach is used in the operation of NIST-F1, the cesium-fountain primary frequency standard at the National Institute of Standards and Technology (NIST) [1]. The fountain is of course the heart of the operation, but two other important technologies play a significant role in the details of how the fountain is operated.

We report the realisation and preliminary study of a frequency standard using a fountain of laser cooled caesium atoms. Our apparatus uses a magneto-optical trap as a source of cold atoms and optical pumping to prepare the atoms in the correct state

[en] For the past 50 years, atomic standards based on the frequency of the cesium ground-state hyperfine transition have been the most accurate time pieces in the world. We now report a comparison between the cesium fountain standard NIST-F1, which has been evaluated with an inaccuracy of about 4x10-16, and an optical frequency standard based on an ultraviolet transition in a single, laser ...

The collisional frequency shift may vary significantly in the vicinity of the cancellation point (fig. ure. 1) and therefore a residual shift is measured and corrected during the normal operation of the fountain as frequency standard. The number of atoms is alternated by varying a microwave field amplitude in the

frequency standards, as well as a measurement tool for the gravitational redshift. Here, we describe the progress made on this project, including our recent observation of a magneto-optical trap (MOT), and the anticipated performance of our transportable Rb fountain frequency standard. INTRODUCTION