"for his discovery of cosmic radiation"

"for his discovery of the positron"

 

Victor Franz Hess	Carl David Anderson
1/2 of the prize	1/2 of the prize
Austria	USA
Innsbruck University Innsbruck, Austria	California Institute of Technology (Caltech) Pasadena, CA, USA
b. 1883 d. 1964	b. 1905 d. 1991

 

Biography: Victor Franz Hess

Victor Franz Hess was born on the 24th of June, 1883, in Waldstein Castle, near Peggau in Steiermark, Austria. His father, Vinzens Hess, was a forester in Prince Öttingen-Wallerstein's service and his mother was Serafine Edle von Grossbauer-Waldstätt.

He received his entire education in Graz: Gymnasium (1893-1901), and afterwards Graz University (1901-1905), where he took his doctor's degree in 1910.

He worked, for a short time, at the Physical Institute in Vienna, where Professor von Schweidler initiated him in recent discoveries in the field of radioactivity. During 1910-1920 he was Assistant under Stephan Meyer at the Institute of Radium Research of the Viennese Academy of Sciences. In 1919 he received the Lieben Prize for his discovery of the"ultra-radiation" (cosmic radiation), and the year after became Extraordinary Professor of Experimental Physics at the Graz University.

From 1921 to 1923, Hess was granted leave of absence, and worked in the United States, where he took a post as Director of the Research Laboratory (created by him) of the U.S. Radium Corporation, at Orange (New Jersey), and as Consulting Physicist for the U.S. Department of the Interior (Bureau of Mines), Washington D.C.

In 1923 he returned to Graz University and in 1925 he was appointed Ordinary Professor of Experimental Physics. In 1931 came his appointment as Professor at Innsbruck University and Director of the newly established Institute of Radiology. He founded the station at the Hafelekar mountain (2,300 m) near Innsbruck for observing and studying cosmic rays.

As well as the Nobel Prize for 1936, which he shared with C.D. Anderson, Hess has been awarded the Abbe Memorial Prize and the Abbe Medal of the Carl Zeiss Institute in Jena (1932); he was also Corresponding Member of the Academy of Sciences in Vienna.

Hess's work which gained him the Nobel Prize, was carried out during the years 1911-1913, and published in the Proceedings of the Viennese Academy of Sciences. In addition he has published some sixty papers and several books, of which the most important were: "Die Wärmeproduktion des Radiums" (The heat production of radium), 1912; "Konvektionserscheinungen in ionisierten Gasen-Ionenwind" (Convection phenomena in ionized gas-ionwinds), 1919-1920; "The measurement of gamma rays", 1916 (with R.W. Lawson); "The counting of alpha particles emitted from radium", 1918 (also with R. W. Lawson); Elektrische Leitfähigkeit der Atmosphäre und ihre Ursachen (book), 1926 (in English: The Electrical Conductivity of the Atmosphere and Its Causes, 1928); Ionenbilanz der Atmosphäre (The ionization balance of the atmosphere - book), 1933; Luftelektrizität (Electricity of the air - book, with H. Benndorf), 1928; "Lebensdauer der Ionen in der Atmosphäre" (Average life of the ions in the atmosphere), 1927-1928; "Schwankungen der Intensität in den kosmischen Strahlen" (Intensity fluctuations in cosmic rays), 1929-1936.

Hess has been American citizen since 1944, and is living in New York.

 

Biography: Carl David Anderson

Carl David Anderson, who was born of Swedish parents - his father was Carl David Anderson and his mother Emma Adolfina Ajaxson - in New York City (USA) on 3rd September, 1905, has spent the bulk of his life in the United States. He graduated from the California Institute of Technology in 1927 with a B.Sc. degree in Physics and Engineering, and was awarded his Ph.D. degree by the same Institute, in 1930. For the period 1930-1933 he was Research Fellow there, subsequently (1933) Assistant Professor of Physics, and Professor of Physics (1939) During the war years (1941-1945) he was also active on projects for the National Defence Research Committee and the Office of Scientific Research and Development.

His early researches were in the field of X-rays. For his doctoral thesis he studied the space distribution of photoelectrons ejected from various gases by X-rays. In 1930, with Professor Millikan, he began his cosmic-ray studies which led in 1932 to the discovery of the positron. He has studied the energy distribution of cosmic-ray particles and the energy loss of very high speed electrons in traversing matter. In 1933 he and Dr. Neddermeyer obtained the first direct proof that gamma rays from ThC" generate positrons in their passage through material substances. Since 1933 he has continued his work on radiation and fundamental particles. Most of Anderson's researches and discoveries have been published in The Physical Review and Science.

Among the scientific honours bestowed upon him, in addition to the Nobel Prize, may be mentioned the following: Gold Medal of the American Institute of City of New York (1935); Sc.D. of Colgate University (1937); Elliott Cresson Medal of the Franklin Institute (1937); Presidential Certificate of Merit (1945); LL.D. Temple University (1949); John Ericsson Medal of the American Society of Swedish Engineers (1960).

In 1946 Anderson married Lorraine Bergman; they have two sons, Marshall and David.

 

Nobel Lecture: Victor F. Hess

Unsolved Problems in Physics: Tasks for the Immediate Future in Cosmic Ray Studies

From a consideration of the immense volume of newly discovered facts in the field of physics, especially atomic physics, in recent years it might well appear to the layman that the main problems were already solved and that only more detailed work was necessary.

This is far from the truth, as will be shown by one of the biggest and most important newly opened fields of research, with which I am closely associated, that of cosmic rays.

When, in 1912, I was able to demonstrate by means of a series of balloon ascents, that the ionization in a hermetically sealed vessel was reduced with increasing height from the earth (reduction in the effect of radioactive substances in the earth), but that it noticeably increased from 1,000 m onwards, and at 5 km height reached several times the observed value at earth level, I concluded that this ionization might be attributed to the penetration of the earth's atmosphere from outer space by hitherto unknown radiation of exceptionally high penetrating capacity, which was still able to ionize the air at the earth's surface noticeably. Already at that time I sought to clarify the origin of this radiation, for which purpose I undertook a balloon ascent at the time of a nearly complete solar eclipse on the 12th April 1912, and took measurements at heights of two to three kilometres. As I was able to observe no reduction in ionization during the eclipse I decided that, essentially, the sun could not be the source of cosmic rays, at least as far as undeflected rays were concerned.

Many esteemed physicists in Europe and America have tried since then to solve the problems of the origin of cosmic rays. The fluctuations of intensity of the radiation already incidentally observed by me in 1912 have been thoroughly studied using apparatuses which have been constantly improved and perfected. An influence from specific sky zones which individual research workers (1923-1927) believed they had found, could not be confirmed later.

In the autumn of 1931 a small observatory for the continuous recording of the fluctuations in intensity of the cosmic rays was set up by me on a 2,300 m high mountain, the Hafelekar at Innsbruck in Austria. A great number of results are already available from there which will only be mentioned here briefly. The determination of a small, regular, daily fluctuation of radiation according to solar time (maximum at midday), which were attributed to atmospheric influences, particularly electrical and magnetic effects in the highest layers of the atmosphere. Further indications of a still smaller fluctuation according to stellar time, which would speak in favour of Prof. A.H. Compton's hypothesis published a year ago, according to which the cosmic rays come from milky-way systems external to, and far-distant from, our own. Further, evidence of simultaneous radiation fluctuations from day to day at two measuring devices spaced at 6 km from each other at heights of 600 and 2,300 m (fitted with ionization chambers, as well as with counting tubes).

On what can we now place our hopes of solving the many riddles which still exist as to the origin and composition of cosmic rays? It must be emphasized here above all that to attain really decisive progress greater funds must be made available. The further improvement of the method of sending up automatically recording instruments to heights above 25 km using pilot balloons, so successfully employed by Prof. Regener (Stuttgart), must be still further expanded and perfected. In conjunction, the many trial methods of automatic radiotelegraphic transmission of observation data as used in America for stratospheric flights will serve a useful purpose. It may well be said that the answer to the question: Of what do the cosmic rays in fact consist before they produce their familiar secondary radiation phenomena in the earth's atmosphere? can only be obtained from numerous measurements in the stratosphere. In conjunction with this, the study of the occurrence of the so-called showers and Hoffmann's bursts (release of enormous quantities of ions resulting from atomic disintegration processes) of cosmic rays at various heights will provide new knowledge about the effects of these rays.

In addition, the tracing of the occurrence of these "showers" in the depths of the earth, in mines and through the immersion of recording apparatus in water to some hundreds of metres depth will yield very important results.

In order to make further progress, particularly in the field of cosmic rays, it will be necessary to apply all our resources and apparatus simultaneously and side-by-side; an effort which has not yet been made, or at least, only to a limited extent. Simultaneous recording with superimposed ionization chambers and Wilson chambers, ionization chambers and sets of counting tubes, has not yet been carried out. The photographic method of observing the tracks of the particles of cosmic radiation, first successfully tried out by Prof. Wilkins (Rochester, USA) merits great attention. The application of a strong magnetic field enables the measurement of the energy of the most penetrating particles to be carried out, and the method may be capable of still further extension and improvement.

The investigation into the possible effects of cosmic rays on living organisms will also offer great interest.

The investigation of the tracks of cosmic rays in strong magnetic fields by means of the Wilson cloud chamber method has led to the discovery of the positron (positively charged electrons), that is, one of the hitherto unknown fundamental components of matter; this was carried out by Prof. Carl Anderson (Pasadena) who was in 1936 awarded the Nobel Prize for this work, at the same time as I myself received the award.

It is likely that further research into "showers" and "bursts" of the cosmic rays may possibly lead to the discovery of still more elementary particles, neutrinos and negative protons, of which the existence has been postulated by some theoretical physicists in recent years.

 

Nobel Lecture: Carl D. Anderson

The Production and Properties of Positrons

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