Gurgen Ashotovich Askaryan (Armenian: Գուրգեն Ասկարյան; Russian: Гурген Аскарьян or Гурген Аскарян) (14 December 1928 – 2 March 1997) was a prominent Soviet-Armenian physicist, known for his discovery of the self-focusing of light, pioneering studies of light–matter interactions, and the discovery and investigation of the interaction of high-energy particles with condensed matter. (See Askaryan effect)
Biography Gurgen Askaryan was born in 1928 in Moscow, Russia to Armenian parents. Both parents were doctors: father Ashot Askaryan, was a general practitioner, and his mother Astgik Askaryan was a dentist. At the age of 18 Gurgen entered the Department of Physics at the Moscow State University, where he started his first research project specializing in the physics of atomic nuclei. Graduated in 1952 and was accepted to the graduate school at the Institute of Chemical Physics (ICP) in Moscow. In 1953, he was transferred to the Lebedev Institute of Physics, and graduated with PhD in 1957. An author of over 200 articles, Askaryan made a significant contribution to the field of high energy physics (see Askaryan effect and ANITA (Antarctic Impulsive Transient Antenna)), acoustics, and optics. For his famous discovery of the self-focusing of light, he received the highest scientific award at the time in the Soviet Union. Shortly after receiving a degree of the Doctor of Science in 1992, Gurgen experienced health problems, which were also accompanied by the worsening of his sister Gohar's health. He and his sister died on the same day on 2 March 1997 in their apartment in Moscow, both because of similar heart diseases.
Scientific career and achievements
Missed Nobel Prize During the third year of his education G. Askaryan proposed a new method of registration of fast charged particles. His idea was the following. Suppose, there is an overheated transparent liquid. A very small amount of energy is sufficient to make it boil. Let a fast charged particle penetrate through this overheated liquid. The particle expends its energy on ionization of atoms located near its trajectory. This energy loss is transformed into heat in amount which is sufficient to induce boiling along particle's trajectory. Then the trajectory becomes observable because many bubbles are created along it. G. Askaryan discussed this proposal with some of his teachers and fellow students. No one objected. However, no one supported him, no one helped to realize the idea. G. Askaryan then was inexperienced in forms and methods of scientific investigation. He even did not publish his proposal. Several years later, in 1952, the same idea was set forth independently by an American physicist Donald Arthur Glaser. He put the idea into practice having assembled the device known now as bubble chamber. This instrument proved to be so useful in high energy physics that D. A. Glazer was awarded with the Nobel Prize in 1960. This event gave rise to Askaryan's deep concern. Of course, he was shaken that Nobel Prize was so near and, so to say, he let it slip. On the other hand, this event helped him to get faith in himself.
Cosmic rays and sound waves G. Askaryan discovered and investigated in details various effects accompanying passage of high energy particles through dense matter (liquids or solids). He showed that hadron-electron-photon showers and even single fast particles may produce sound pulses. Ionization losses are quickly converted into heat, and the small region adjacent to trajectory undergoes quick thermal expansion thus generating sound waves. These results gave a new approach to the study of cosmic rays. Before, investigations of cosmic rays were based on direct interaction of cosmic ray particle with a detector. Askaryan's results made it possible to detect showers and single particles using sound receivers situated at some distance from the event. Several years ago, the registration of energetic particles and showers with sound detectors in sea water was planned as an important part of global monitoring.
Cosmic rays and electromagnetic waves G. Askaryan also showed that cosmic ray showers emit electromagnetic radiation, thus giving yet another way for their detection. Before him it was commonly assumed that electron-photon showers do not emit electromagnetic radiation since the electrons and positrons are created in pairs. Askaryan's analysis led to the conclusion that in an electron-photon shower there is an excess of negative charge (excess of electrons). These excess electrons are knocked out from atoms either by photoeffect or by shower electrons and positrons (ionization). At the same time, due to the annihilation process the number of positrons decreases. Thus, there is an electric current created by the excess electrons associated with shower. This variable current is the source of electromagnetic radiation. Therefore, every shower is the source of electromagnetic radiation. These studies opened new perspectives for distant registration of cosmic ray showers. These investigations paved the way for distant registration of cosmic ray showers. Now many radio-astronomical stations are conducting observations on cosmic ray showers.
Intense laser beams and radiation acoustics Later G. Askaryan showed that intense laser beam passing through matter also generates sound waves. This effect may be used for processing and for destruction of matter. As a result of this series of investigations, a new branch of physics was created, radiation acoustics, and G. Askaryan was the founder.
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