Bay, Zoltán

His name is well-known for people interested in the history of science and technology. Though he was not awarded the Nobel Prize, Zoltán Bay has become one of the most significant physicists in basic research of the natural sciences in the 20th century. He was a participant and organiser of technological development and realised industrial applications, as well. He is most famous for the lunar radar echo experiment after the 2nd World War. However, few people know about his definition of the metre based on the velocity of light and his results in the development of photoelectron multiplier tubes.

He has taken his final examination at the famous Reformed (Calvinist) College's secondary school in Debrecen

in 1918, then he enrolled at the Faculty of Arts at the Royal Hungarian University of Sciences

in Budapest and at the same time he was admitted to the József Eötvös College. In 1923, he was awarded a secondary school teacher's diploma, and in 1926 received his doctorate in physics.

From 1926 to 1930, he worked on a scholarship in Germany, became the member of the Collegium Hungaricum in Berlin and worked at the Physical-Chemical Institute of the University of Science in Berlin.

He developed a new method of spectroscopy (1929), by means of which he was able to study the excited emission spectrum of gases and proved the existence of free N-atoms in active nitrogen. He became acquainted with John von Neumann, who later became one of his friends.

After returning home, he was appointed as senior lecturer at the Ferencz József University of Sciences

of Szeged

and, in 1935, as professor of the Department of Theoretical Physics. He studied of Compton scattering; paid special attention to the relationship between quantum mechanics and biology; and measured the current and voltage of the heart and created the idea of pacemakers. In this research Albert Szent-Györgyi, who was the head of the Biochemical Department of the University of Science of Szeged, played an important role.

In 1936, Lipót Aschner, General Manager of United Incandescent Lamp and Electrical Co. Ltd. invited Bay to be the head of the Tungsram Research Laboratory, following Ignác Pfeifer.

Here he improved the detection of the photon-electron coincidence of the Compton– effect in the ultraviolet and visible domains. The idea of the development of a particle counter based on electron multiplication arose in 1937. At that time a sensitive multiplier was already available, the dark current of which corresponded to flow of 40 electrons per minute. In 1938, the sensitivity was improved by means of dinodes of high emission capability and in this way the detection of a and b particles also became possible.

A fast operating coincidence circuit had to be developed for the electron multiplier. Bay and his colleagues developed a device having a resolution of 1...10 ns, with which they were ahead of laboratories all over the world.

He became a correspondent member of the Hungarian Academy of Sciences

in 1937 and an ordinary member in 1945. In 1938 he undertook the direction of the Nuclear Physics Department established in the József Palatine Technical and Economic University

and supported by Lipót Aschner.

In 1942, radar experiments of military purpose started inTungsram for direction finding and distance measurement aiming the production of domestic active microwave devices and using them to accomplish microwave terrestrial connections and the development a radiolocator for anti-aircraft defence. The Bay research team obtained experience in the so-called pulse echo method.

The Moon echo experiment started in 1944 and the measurement were successful in 1946.

Leaving Hungary in 1948 owing to the worsened political conditions, he continued his research of fast coincidence as a professor at the George Washington University

in the United States.His most important achievement here was to complete work on development of the electron multiplier, which he had begun in Hungary in 1938.

In 1955, he was appointed as the head of the Nuclear Physics Department at the American National Bureau of Standards,

where he measured the frequency and velocity of light by a previously unknown method. On the basis of the of his research, the conference of the International Weights and Measures Bureau

held in 1983 accepted as a standard the definition of the metre as recommended by Bay. It became possible to use the velocity of light as base unit of length measurement and to create the “light measured metre”.

From 1972, he was a researcher as a retired professor at the Physics Department of the American University (Washington DC).

From the eighties he often visited Hungary.

His return with his friend, Albert Szent-Györgyi was a remarkable event in Hungary.

Memberships: Associate (1937) and ordinary (1945) member of the Hungarian Academy of Sciences, honorary doctor of the University of Edinburgh (1978), honorary member of the Hungarian Academy of Sciences (1981), honorary member of the Roland Eötvös Physical Society (1981), honorary doctor of the Technical University of Budapest (1986), honorary citizen of the town of Gyula (1989), honorary doctor of Lajos Kossuth University of Sciences (Debrecen) (1990), honorary President for life of Hungarian Electrotechnical Association (1990), honorary doctor of the József Attila University (Szeged) (1991).

Honours: Order of Service (Ministry of Commerce, United States) (1970), Boyden Prize (1980), Flag Order of Rubies of the Hungarian Republic (1990), Kálmán Szily Commemorative Medal, (Természet Világa - The World of the Nature, periodical, 1991)

Debrecen College of Reformed (Calvinist) College
The Calvinist College of Debrecen was founded in 1538, and during the past few centuries its name was written in the Hungarian and universal cultural history with golden letters. Educational work has been going on between the walls of the college since the very beginning on different levels.
Students of the College came from the common people - from the families of peasants, craftsmen, commoners or from the lower nobility – and after finishing their studies or after foreign study-tours longing for years they entered the nation's service.
They established hundreds of rural schools, printing houses were founded, churches were built on the Hungarian plain and the Calvinist preachings in these churches were held in Hungarian language.
In the library of the College the most valuable works of science were collected from the beginning, and the library also provided schoolbooks, educational appliances and maps for rural schools.
During the 1848-1849 revolution and war of independence the chamber of deputies of the Hungarian House of Parliament took their sessions between the walls of the College in the Oratory from January 9, 1849 to May 31, 1849.
In the end of year 1944 Debrecen became the capital of Hungary for the second time, and on December 21, 1944 the temporary national assembly was set on also here between the walls of the Oratory.

The Eötvös College
As a teacher at the end of the 19th century Loránd Eötvös perceived that a great number of talented students break their studies, due to lack of financial support. To solve this problem in 1895, during the time he was minister of education, he established a scientific residential college, which was named the József Eötvös College, after his father. Within the framework of the college future secondary school teachers received excellent tuition and took part in special tutorials to promote individual scientific work. It was the first action towards creating further programs in higher education which were needed for the systematic large-scale training of young scholars in the following decades .
To support the poorest students no fees were required for thirty of the one hundred places.
Students working in various academic fields were successfully mixed in interdisciplinary discussion groups which facilitated confronting of diverse views.
To promote natural sciences, Eötvös advised Andor Semsey, a great patron of Hungarian science, to establish a scholarship for young graduates who wished to devote themselves to scientific studies. This tradition of careful scholarship – like for graduates of Oxford and Cambridge, or of Harvard and Yale - was maintained during the first decades of 20th century.

Pfeifer, Ignác
(Szentgál, September 30th, 1867- Budapest, September 7th, 1941)

Pfeifer, Ignác In September 1887 he started his studies in the section of chemistry at József Technical University and got a diploma of chemical engineering here in 1892, and was an assistant lecturer for two years at the Faculty of Chemical Technology. A product of this period is the book entitled Alcohol tables of 735 pages
Laying down his position as assistant lecturer he started to work as a chemist in the chemical laboratory of MÁV (Hungarian State Railways). First he developed a procedure for the determination of the hardness of water; since then the so-called Wartha-Pfeifer process has been a part of the history of water chemistry. In his publications he dealt with the problems of the chemical purification of boiler waters and the reduction of corrosion and crustification for four years. He was engaged in heating technique, studied the suitability of home coals and proved the superfluousness of a considerable percentage of the import. His book entitled „Survey of Boiler Furnace Constructions" was published in 1898.
In 1900, after successful trial lecture he was appointed private professor at József Technical University. As a private professor he also undertook the edition of two journals.
Pfeifer opened a technical bureau in 1903. At that time he was engaged in problems of gas generators and assembled a gas analysing apparatus for them, he patented a process relating to the production of tar-free generator gas from brown coal. With Wartha he took part in the development of the gas factories of Budapest and he studied composition of natural gas in Hungary. He made a detailed proposition regarding the exploitation of natural gas. He was successfully engaged in the halogenation of carbon hydrides.
In 1907, on the recommendation of Wartha, Pfeifer was honoured with the title of assistant professor. He got the nomination of full professor at the Department of Chemical Technology and was for seven years one of the most successful professors at the Technical University
Later he was adviser for Gaswerk Baumberg in Hamburg, but he soon accepted the invitation of Lipót Aschner to be the head of the research and development laboratory to be established in United Incandescent-Lamp and Electrical Co. Ltd.
Pfeifer played a determining role in these years in the Hungarian Chemical Society where he was elected acting president in 1929.

photoelectron multiplier tubes
Extremely sensitive detectors of light multiplying the signal produced from the incident light from which single photons are detectable.
Photomultipliers are constructed from a glass vacuum tube which houses the photocathode, a number of electrodes, called dynodes and an anode. Incident photons strike the cathode material which produces electrons as a consequence of the photoelectric effect. The anodes and the series of dynodes are held at increasing potential and the accelerated electrons are multiplied by the process of secondary emission, producing increasing number of electrons at each stage.
Finally on the anode the accumulation of electron charge results in a sharp current pulse indicating the hit of a photon at the photocathode.
Amplification can reach as much as 108 such pulses originating from single photons are measurable.

Lunar radar echo experiment of Zoltán Bay and his team
On 6. February 1946. dr. Zoltán Bay and his team obtained an important scientific result: they were able to detect a radar echo signal from the Moon. Based on earlier experiments, they developed microwave electronic tubes, which were good for practical purposes, as well. Using the electronic tubes, successful transmission and reception experiments were carried out and the first impulse-operated radiolocator was developed. During the distance measurements made by the locator, Zoltán Bay had a good idea: the equipment could be used for scientific purposes, as well. Using the Moon as a reflective area, an investigation of space could be commenced.
Owing to the poor post-war technical conditions (after the long-lasting siege of Budapest, soviet troops had taken down and carried the machine pool of the factory) Bay's idea was to send out signals in the form of pulse packages and to sum up the received echo-signals - synchronised to the outgoing pulse - using a series of hydrogen coulombmeters as storage unit for the signal measurement under noise level.
The signal reflected from the Moon was independently measured, not more than four weeks after the American researchers.

definition of the metre
In the past the meter was defined by an artifact or as one ten-millionth of the length of the earth's meridian along a quadrant (one-fourth the polar circumference of the earth). The corresponding International Prototype Metre standard bar made of platinum-iridium. This was the standard until 1960, when the new SI system used a kripton spectrum measurement as the base. (The metre as equal to 1,650,763.73 wavelengths of the orang-red emission line in the electromagnetic spectrum of the krypton-86 atom in vacuum.)
Since 1983 the meter has been defined as the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second, from which follows the fundamental constant c, the speed of light. Definitions based on the physical features of light are more precise and reproducible because the properties of light are considered to be universally constant.
For laboratory-scale spaces, however, the meter is usually realized not through a time-of-flight measurement but rather through the equivalent relation of c/í for electromagnetic radiation in vacuum. In practice, the measurement requires a laser of known frequency, and an interferometer.
The up-to-date optical frequency standards are very accurate. Iodine-stabilized helium-neon lasers, for example, with accuracy of 2,5.10^-11 or better, have been commercially available for years. This level of accuracy corresponds to roughly one millimeter relative to the circumference of Earth, and standards with several orders of magnitude better accuracy are found at national measurement laboratories. In general the precision of the interferometer limits the accuracy of a distance measurement and not that of the lasers.