gran·ite (n)A very hard, granular, crystalline, intrusive igneous rock consisting mainly of quartz, mica, and feldspar and often used as a building...Used in similes and metaphors to refer to something very hard and impenetrable.
MASER Muzzamil Shaikh Sukkur IBA Mir Muhammad Lodhro Electrical (Telecom) Engineering1/11/2013
History and background• 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
MASER’s Microwave Amplification by the Stimulated Emission of Radiation Masers in Space
Microwave• Masers are just like lasers except that the radiation they emit is in the microwave part of the electromagnetic spectrum.• This light has a longer wavelength and less energy than the visual light emitted by lasers.
Amplified• Radiation from a maser or laser is much more intense than radiation from other light sources.• The amplified light from lasers can be strong enough to cut through granite.• The amplified light from Masers can be strong enough to be seen from billions of light years away.• To radio telescopes, masers look like very small, very bright dots. Just as if someone was shining a laser-pointer at you from across the room.
Stimulated Emission• Masers are so powerful because they emit from regions with a population inversion• These regions are unstable and can lead to the stimulated emission of large quantities of radiation.
Population Inversion• Every electron in a system has a certain amount of energy.• Population Inversion occurs when most of the electrons are in the higher energy state. Normal population Inverted population
Stimulated Emission• one of the electrons randomly jumps to the lower energy level. When it does, it emits a photon with an energy equal to the energy difference between the two levels.
Radiation• Light bulbs emit electromagnetic radiation in a most disorganized way.• MASERS emit radiation much more orderly. Because they were produced by stimulated emission.• All the photons are monochromatic, in phase, similarly polarized, and travel in the same direction.
First Maser• The first maser was an ammonia- beam maser (1954)• The two energy levels used in the ammonia maser are vibrational states of the ammonia molecule N H H• The hydrogen atoms can be considered to rotate H H H H N• The nitrogen atom oscillates between two positions, above and below the plane of the hydrogen atoms
Monochromatic Light is a wave with frequency, wavelength and energy. The “light” emitted by a MASER is of one frequency, wavelength and energy. Color is related to frequency and so the light is said to be monochromatic. (Mono = one, chromatic = color) monochromatic not monochromatic
In phase• Light is a wave and has a wavelength.• If two waves begin at the same point, they are in phase. Added together, their amplitude increases.• When two waves begin at different points, they are out of phase. If they are added together, their amplitude decreases.
Polarization VerticalWaves can bepolarized in fourdifferent ways. All Horizontalthe microwavesemitted by a maser arepolarized in the sameway. Right handed left handed
Masers in Space Several different types of molecular masers have been discovered in space. They produce radiation using chemicals including: Hydroxyl (OH)Formaldehyde (H2CO) Ammonia (NH3) Hydrogen Cyanide (HCN) Water (H2O) Silicon Monoxide (SiO) Methanol (CH3OH)
Each maser produces radiation at acharacteristic frequency. Because these sources are so strong, astrochemists use them to find and identify new chemicals in space.
Masers reveal the characteristicsof their environment.• They can be used as probes to determine the density, temperature, pressure, and velocity of a region of space.• Masers were used in the first proof of the existence a black hole!• Masers were found circling a massive object. They circled very fast, indicating that the object had to be very dense. Mathematics showed that an object so dense could not be anything but a black hole.
Astrophysical Maser• For an Astrophysical Maser to function in space, it requires a magnetic field for the resonant frequency to be formed• 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
Reconnaissance aircraft • Reconnaissance aircraft are primarily used to gather intelligence (collect information). • They are equipped with photographic, infrared, radar, and television sensors. • Reconnaissance aircraft are normally the fastest aircraft in the military, an example being the SR-71 Blackbird.