Cesium Beam Atomic Time and Frequency Standards

Beehler, R. E.; Mockler, R. C.; Richardson, John M.

doi:10.1088/0026-1394/1/3/004

Cited by 47 publications

(10 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The unit of all these time scales is the Systeme International (SI) second, defined as the duration of 9 192 631 770 cycles of radiation from the transition between the two hyperfine levels of the ground state of cesium 133. The fractional accuracy of cesium atomic clocks is better than 10 l * (Ramsey, 1988(Ramsey, , 1990; see also Beehler et aL, 1965). TAI, the most precisely determined time scale available for astronomical use, is established by the Bureau International des Poids et Mesures in Paris from analyses of data from cesium clocks in many countries.…”

Section: Time Delay and Doppler Frequencymentioning

confidence: 99%

Planetary radar astronomy

1993

View full text Add to dashboard Cite

Radar is a powerful technique that has furnished otherwise unavailable information about solar system bodies for three decades. The advantages of radar in planetary astronomy result from (1) the observer's control of all the attributes of the coherent signal used to illuminate the target, especially the wave form's time/frequency modulation and polarization; (2) the ability of radar to resolve objects spatially via measurements of the distribution of echo power in time delay and Doppler frequency; (3) the pronounced degree to which delay-Doppler measurements constrain orbits and spin vectors; and (4) centimeter-to-meter wavelengths, which easily penetrate optically opaque planetary clouds and cometary comae, permit investigation of near-surface macrostructure and bulk density, and are sensitive to high concentrations of metal or, in certain situations, ice. Planetary radar astronomy has primarily involved observations with Earthbased radar telescopes, but also includes some experiments with a spaceborne transmitter or receiver. In addition to providing a wealth of information about the geological and dynamical properties of asteroids, comets, the inner planets, and natural satellites, radar experiments have established the scale of the solar system, have contributed significantly to the accuracy of planetary ephemerides, and have helped to constrain theories of gravitation. This review outlines radar astronomical techniques and describes principal observational results.

show abstract

Section: Time Delay and Doppler Frequencymentioning

confidence: 99%

Planetary radar astronomy

1993

View full text Add to dashboard Cite

show abstract

“…The high accuracy capability resulted (in October of 1964) in the declaration of the International Committee of Weights and Measures that the physical measurement of time be based on the F, m_ = the machine at the National Research Council of Canada; and the machine at the Physikalisch-Technische Bundesanstalt in Germany-have an evaluated accuracy (one sigma) of about 5 parts in 10 . This is a greater proven accuracy than for any other type of device known [9].…”

Section: The Cesium Beammentioning

confidence: 87%

“…Those parameters which, in the cesium beam, alter the transition frequency from its free atom value have been thoroughly studied [9].…”

Section: The Cesium Beammentioning

confidence: 99%

The physical basis of atomic frequency standards

Risley¹

1969

View full text Add to dashboard Cite

A tutorial discussion of the physical basis of atomic frequency standards is given. These principles are then related to the conditions under which an atom can be used as the working substance of a stable and accurate frequency standard. The three primary examples of atomic frequency standards--the hydrogen maser, the cesium beam, and the rubidium gas cell--are then discussed in terms of these principles and conditions. The functions of the fundamental parts of each device become apparent through this development.

show abstract

“…The inaccuracy of a primary frequency standard may also be bicategorized. Through the procedure of evaluation of the parameters that affect the frequency of the primary standard, there is associated with each parameter both a bias (possibly zero) and a random uncertainty in our knowledge of its effect [5]. Excellent stability of the time scale allows the possi-107 s 141.…”

Section: L2mentioning

confidence: 99%