![]() Winkler of the US Naval Observatory.Ĭesium atomic clocks are the most accurate time and frequency standards, serving as the primary standard for the definition of the second in the International System of Units (SI) (the modern form of the metric system). The first cesium clock was built by Louis Essen in 1955 at the UK National Physical Laboratory and promoted worldwide by Gernot M. The cesium pattern is a primary frequency pattern in which photon absorption by transitions between the two hyperfine ground states of cesium-133 atoms is used to control the output frequency. Please help update this article to reflect recent developments or new information available. The reason is: it needs to reflect the 2019 redefinition of SI base units, which came into effect on May 20, 2019. With our innovative optical cesium atomic clocks, we are taking the next level of lifetime stability and performance. Now you must go further than ever to meet the even more stringent requirements of the future. This technology has proven to offer excellent performance and reliability in many applications, including mission-critical use cases. You may be interest in: 7 Best Electric Blankets of 2022 Communication service providers appreciate the standard-compliant SNMP interfaces for seamless end-to-end control from their umbrella management systems. With technology that ensures phenomenal accuracy, performance levels that exceed ITU-T G.811/Stratum 1 PRC, and a 10-year long-life cesium tube, all in an extremely compact size, our cesium watches they are the best in their class. Ideal for ensuring timekeeping accuracy in today’s and tomorrow’s applications, they offer outstanding performance over a wide temperature range and a unique set of operational features, including greatly improved and easy integration into industrial, professional and mobile systems. Our cesium units improve overall network performance and prevent upstream clock errors from propagating throughout the network. With our technology, network operators can rely on a frequency source that delivers even better levels of accuracy than required over its entire lifetime. Our cesium atomic clock achieve this and more. What you want, as with microwave clocks, is a "narrow" transition, which means it should have a long lifetime.Meeting precise timing specifications requires the implementation of a primary reference clock that generates signals at all times, along with very high frequency stability. These days, it has become possible to use optical transitions at much higher frequencies (and therefore higher Q's), and there is a lot of work on "optical" clocks. Another advantage Cs has is that there is only one stable isotope, meaning you don't have any issues arising from having multiple isotopes around, or having to purify it. Other atoms and ions have been in common use, including Rubidium, Hydrogen, and Mercury ions. Because of the technology available at the time, microwave transitions such as this (9192631770 Hz for Cs) were the limit of what could be measured. Put another way, as an oscillator, it has a very high Q. That means for a given interrogation time, you will maximize the number of oscillations between these two states, giving a more precise measurement. Cesium has the advantage of having the largest hyperfine structure, that is, the energy difference of the two electron spin states in the presence on the nucleus's magnetic field. Since they have a single electron in addition to a filled shell, they have a fairly simple electronic structure. As sophiecentaur has noted, there are reasons for using alkali atoms, the ones on the left-hand side of the periodic table. I don't know if today is possible to use other systems instead of caesiumĬesium was actually chosen for a number of reasons. ![]() Then a counter detect the exact frequency of the oscillator, so stabilized, that is the number of cycles every second, or the second, knowing the number of cycles so counted. This variation is measured by a photodetector and immediately the electronic circuit corrects the oscillator's frequency to bring again the light intensity to its maximum value. ![]() When the exciting frequency varies slightly, the atoms, in those experimental conditions, cannot absorb that frequency anymore and so the emitted light intensity is reduced. Remember that, for example, caesium was one of the first metals to be used for photoelectric cells because you can ionize it with visible light. Caesium was initially used because its electronic levels can be excited with radiofrequencies (microwaves) produced by an electronic circuit and then they de-excitate generating light (don't know the details of the process) you can't do the same, in a rather simple way, with other atoms.
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