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Transcript
Masers
(Microwave Amplification by Stimulated
Emission of Radiation)
Ariunaa Bayarbat
Chuck Protheroe
John Leone
Phys 4D 2006
SRJC
What’s a maser?
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Maser is a microwave beam that has been amplified through coherent stimulated
radiation emission
What this means is that a molecule is in a certain environment where its outer electrons
are in a high energy state and is bombarded by a photon (in this case a microwave)
which causes the electrons to ‘jump down’ in energy level and release another photon so
that both photons have the same phase, frequency, and direction. This makes the photons
add up and create an amplified beam.
Masers occur naturally in space and also are created in laboratories
History and background
• A maser is based on Einstein’s 1917 stimulated emission
principle
• Two soviet scientists, Nikolay Basov and Alexander
Prokhorov came up with the idea in 1952
• In 1953, the first ammonia maser was developed by
Townes, Gordon and Zeiger at Columbia University.
• Norman Ramsey created the first laboratory hydrogen
maser in 1960. His design is still being used today
• Discovery of laser (optical maser) was followed in
December of 1958
• Natural masers in space have been discovered since 1965
• Everyone has different names for masers, such as losers
Maser Molecule Types
• Atomic beam
Hydrogen and ammonium
• Gas
Rubidium
• Solid state
Ruby
• Dual noble gas
He3 and 129Xe
• Liquid
Water
Maser Beam Types
• Originally masers emitted only microwaves
• Upon the discovery of emissions of other wavelengths in
different parts of the EM spectrum the definition of a maser
became hazy
• Now masers can be considered as emitting solely microwaves,
or any type of stimulated radiation emission depending on the
classification used
• Basically, despite what you call it, amplification by stimulated
emission of radiation can happen for any wavelength in EM
spectrum, some are more common then others
• Means beam can be x-ray, infra red, radio, visible light(laser),
etc.
Laboratory vs. Natural
• Naturally occurring masers are usually
much weaker than laboratory made masers.
So radio telescopes are used to detect
• The laboratory made masers usually emit
more powerful beams because, with
technology, we can create the perfect
coherence, resonant frequencies, etc.
• Natural masers use magnetic field to
polarize movement and create coherence
Laboratory made Hydrogen Maser
• The high frequency and regularity of
hydrogen maser can be used as a
standard to keep the atomic clock
accurate (HMC)
• Works similarly to a laser with two
mirrors designed to reflect
microwaves
Astrophysical Maser
• For an Astrophysical Maser to function in space, it requires a magnetic
field for the resonant frequency to be formed
• Less effective than engineered masers, because of the inability to make
a perfect resonant cavity.
• Can be used to identify conditions in space, such as temperature,
magnetic field, and velocity.
• OH, water, methanol- common types
Maser Applications
• Improved atomic clock
• Electronic amplifiers in radio telescopes
• Masers are also used as a low-noise radio frequency
amplifiers in satellite communication and radio astronomy
• Used as a non-lethal weapon (VMADS) for military
purposes
Works Cited
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http://en.wikipedia.org/wiki/Maser
http://www-ra.phys.utas.edu.au/~sellings/queens.html
http://www.factmonster.com/ce6/sci/A0832083.html
http://www.foundationalquestions.net/townes/articles/lasers.asp
http://www.absoluteastronomy.com/ref/maser
http://www.reference.com/browse/wiki/Maser
http://www.Globalsecurity.org/org/news/2001/010227/zapper.htm
web.haystack.mit.edu/RET/Astrochemistry