Exercise 9. Match the following nouns with their definition.

1.	acronym	a.	a hole or empty space inside something solid
2.	amplifier	b.	public praise and reward for somebody's work or actions
3.	cavity	c.	the production or sending out of light, heat, gas, etc
4.	concept	d.	the act or process of changing something from one form, use or system to another
5.	conversion	e.	a piece of equipment for producing oscillating electric currents
6.	emission	f.	the area around a particular place
7.	generator	g.	an electrical device or piece of equipment that makes sounds or radio signals louder
8.	oscillator	h.	an idea or a principle that is connected with something abstract
9.	recognition	i.	a word formed from the first letters of the words that make up the name of something
10.	vicinity	j.	a machine for producing electricity

Exercise 10. Find 10 active words in the table. The words are written horizontally, vertically and diagonally.

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TEXT 1

 

Maser

The devices known as masers and lasers serve as amplifiers and generators of radiation. Their common characteristic is that they make use of the conversion of atomic or molecular energy to electromagnetic radiation by means of the process known as stimulated emission of radiation. When the wavelength of the emitted radiation is in the vicinity of 1 cm we speak of microwave amplifiers or masers. Instruments which generate or amplify visible or nearly visible radiation are called optical masers or lasers.

The history of the invention or the evolution of these devices may be divided into the following periods.

The relevant phase of the premaser period started with the discovery of the existence of the stimulated emission process and ended with the recognition by many physicists of the possibility that this process might lead to a radiation amplifier. This period extends from 1916 to 1953. In 1917, it was Albert Einstein who was the first to recognize the existence of stimulated emission, but not until the 1950s when the first device was demonstrated.

The maser period begins with the publication of an article by Basov and Prokhorov and the construction of the first operating maser by Townes, Gordon, Zeiger. Basov and Prokhorov gave a detailed theoretical exploration of the use of molecular beams in microwave spectr o scopy. The article of Basov and Prokhorov contained detailed calculations pertaining to the role of the relevant physical parameters, the effects of line-width, cavity dimensions, and the like. Thus the quantitative conditions for the operation of a microwave amplifier and generator were found.

In 1954 at Columbia University Charles Townes and two of his students announced the construction and operation of a device that may be used as a high resolution microwave spectrometer, a microwave amplifier, or a very stable oscillator. They named the device a “maser” – an acronym for microwave amplification by stimulated emission of radiation.

From 1958 on, many masers were constructed for applications in radio astronomy and as components of radar receivers. These masers were mostly of the ruby type. Their design became a part of the engineering art and research interest turned toward the extension of stimulated emission techniques in the visible and infrared regions. Arthur Schawlow of Bell Laboratories and Townes proposed extending the maser concept to the optical frequency range in 1958. Born in Greenville, South Carolina, Townes joined the technical staff of Bell Telephone Laboratories Inc. and worked on radar bombing systems during World War II. In 1948 he joined the faculty of Columbia University and three years later had the idea that resulted in the construction of the maser. From 1959 to 1961 Townes served as a vice president and a director of research of the Institute for Defense Analysis in Washington, D.C. He then was appointed the professor of physics at Massachusetts Institute of Technology.

The maser period extends from 1954 to 1960.