Seth Gordon,age 13, of Eugene, Ore., for his question:
WHAT IS A MASER?
An atomic clock is a device used for measuring time intervals by measuring the frequency of electromagnetic waves given off, or absorbed, by atoms or molecules. In an atomic clock, such frequencies are extraordinarily stable. Some atomic clocks gain or lose no more than a few seconds in 100,000 years. A device called a maser is used as an atomic clock
A maser is an electronic device that generates and amplifies radio and light waves. In addition to using them as atomic clocks, masers are also used to amplify weak radio signals, such as those from distant stars.
The word maser stands for Microwave Amplification by Stimulated Emission of Radiation.
A laser is an optical maser. It produces an extremely narrow beam of light. Scientists hope that laser beams may be used to transmit radio and television signals.
The essential part of a maser is a substance that has been put into an excited, or high energy, state. In this state, the atoms of the substance are able to radiate energy of a particular frequency when stimulated, or triggered, by a radio or light wave of the same frequency. The energy released by the atoms is added to the stimulating wave, and thereby amplifying it.
In the ammonia maser, heat is used to excite ammonia gas.
In the ruby maser, radio waves are used to excite the chromium in a synthetic ruby placed in a magnetic field. Ruby masers are operated at temperatures of only a few degrees above absolute zero.
The first ammonia maser was built in the United States in 1953. Several years later American and Russian scientists developed the ruby maser. The first continuously operating laser was produced in the United States in 1961.
Mechanical clocks are disturbed by many things, including changes in temperature and the wearing of parts. Atoms and molecules used in atomic clocks include cesium atoms and molecules of ammonia gas.
Atomic clocks control the time signals sent out to the world from national laboratories, such as the Bureau of Standards. In 1964, scientists throughout the world adopted the vibration rate of an atomic clock as the standard for defining time units.