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#Maser elyoum series

This is done using a series of phase-locked loops and a high performance quartz oscillator. The coherent receiver is used to amplify the signal and change the frequency.

The microwave signal coming out of the maser is very weak (a few pW) and the frequency is extremely stable but can not be changed.

A small fraction of the signal in the microwave cavity is coupled into a coaxial cable and then sent to a coherent receiver.

The resonant frequency of the microwave cavity is exactly tuned to the hyperfine structure of hydrogen: 1420 405 751.768 Hz. This combination of amplification and feedback is what defines all oscillators. The stimulated emission amplifies the microwaves on each pass through the beam.

A high quality factor microwave cavity confines the microwaves and reinjects them repeatedly into the atom beam.

From this state, the atoms can decay to the lower state and emit some microwave radiation. After passing through an aperture and a magnetic field, many of the atoms in the beam are left in the upper energy level of the lasing transition. This is done in a way that is very similar to the famous Stern-Gerlach experiment.

The next step is "state selection"-in order to get some stimulated emission, it is necessary to create a population inversion of the atoms.

This is done by submitting the gas at low pressure to an RF discharge (see the picture on this page).

First, a beam of atomic hydrogen is produced.

Here is a brief description of how it works:

The maser oscillation relies on stimulated emission between two hyperfine levels of atomic hydrogen. Today's masers are identical to the original design. It was Norman Ramsey and his colleagues who first realized this device.

This is the international time scale, which is coordinated by the Bureau International des Poids et Mesures, or BIPM. Together with other types of atomic clocks, they constitute the "Temps Atomique International" or TAI. Today, the most important type of maser is the hydrogen maser which is currently used as an atomic frequency standard. They are also used as electronic amplifiers in radio telescopes. These "atomic frequency standards" are one form of atomic clock. Masers serve as high precision frequency references. The dual noble gas maser is an example of a masing medium which is nonpolar. When atoms have been put into an excited energy state, they can amplify radiation at the proper frequency.īy putting such an amplifying medium in a resonant cavity, feedback is created that can produce coherent radiation. The maser is based on the principle of stimulated emission proposed by Albert Einstein in 1917. For their research in this field Townes, Basov and Prokhorov were awarded the Nobel Prize in Physics in 1964. Schawlow to describe the principle of the optical maser, or laser, which Theodore H. The device used stimulated emission in a stream of energized ammonia molecules to produce amplification of microwaves at a frequency of 24 gigahertz. Zeiger built the first maser at Columbia University in 1953. They subsequently published their results in October 1954. Theoretically, reflecting principles previously discussed by Joseph Weber at the June 1952 conference of the Institute of Radio Engineers, the principle of the maser was described by Nikolay Basov and Alexander Prokhorov from Lebedev Institute of Physics at an All-Union Conference on Radio-Spectroscopy held by USSR Academy of Sciences in May 1952.