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Jeno N. Barnothy (1904–1996)

Published onJan 01, 1997
Jeno N. Barnothy (1904–1996)

AIP Emilio Segrè Visual Archives,
John Irwin Slide Collection

Jeno Barnothy, an outstanding pioneer of cosmic ray research and noted astrophysicist, died on 11 October 1996 at the age of 92 in Evanston, Illinois. He was born on 28 October 1904 in Kassa, Hungary (now Slovakia) and received his PhD in 1939 at the Peter Pazmany (now Loránd Eötvös) University, Budapest, Hungary. He was awarded of merit of the Hungarian Academy of Sciences in 1939 and the Eötvös Order in 1948. He worked from 1935 to 1948 in the Institute for Experimental Physics of the Loránd Eötvös University, first as an assistant professor and later as an associate and full professor.

Jeno Barnothy and a colleague, Madeleine Forro, became interested in research on cosmic rays using the coincidence technique that had been developed recently by Bothe and Kohlhorster. They built large Geiger-Müller counters and designed one of the first cosmic ray telescopes to study the isotropy of cosmic rays, their sidereal time periodicity, and their energy spectrum up to very high energy. Barnothy and Forro also explored the absorption of cosmic rays in the atmosphere and deep underground in the Dorog coal mine near Budapest and started a cosmic ray research center in Hungary that attracted a growing number of students. Their scientific achievements were cited in many papers in the cosmic ray literature and in handbooks including those of W. Heisenberg and L. Janossy.

Madeleine Forro and Jeno Barnothy married in 1938, becoming husband and wife and scientific colleagues for the rest of their long lives. After World War II, the Barnothys, both faculty members at the Roland Eötvös University, attempted to re-establish cosmic ray research in Hungary, but were unable to gain support from the authorities. They therefore left Hungary for the United States in 1948, where they first taught physics at Barat College, Lake Forest, Illinois, from 1948 to 1953, before settling in Evanston.

Once in America, the Barnothys' scientific interest shifted from cosmic rays to astrophysics. Their major achievement in this field was the prediction that high luminosity and rapid variability of quasars was partly due to their being gravitationally lensed. In a series of papers published in the 1960s and 1970s, they were among the first few astronomers to promote the idea of gravitational lensing.

In addition to their involvement in cosmic ray physics and astrophysics, the Barnothys became interested in biophysics, carrying out a number of experiments concerning the effects of magnetic fields on living creatures and founding the Biomagnetic Society. Jeno was active in a number of other American and international organizations, including the AAS, the American Physical Society, the German Astronomical Society, and the IAU. The Barnothys invited large numbers of scientists to their home in Evanston and also organized small seminars. They had relatively few collaborators in the United States, but one of the important lensing papers was co-authored by the late Beatrice M. Tinsley.

The authors of this notice first met Jeno in Budapest, when he was young, talented, and already a respected scientist. Ervin Fenyves began his PhD dissertation under the Barnothys' supervision and continued scientific contact and warm friendship with them throughout their lives.

Madeleine Barnothy Forro died in March 1993 (obituary in BAAS 26, 4) and Jeno followed his beloved wife three years later. With the death of Jeno Barnothy, the community of physicists and astrophysicists has lost one of its important ties to the beginning of cosmic ray physics. He will be long remembered by his students, colleagues, and friends for his warm humanity, continuous helpfulness, and excellent sense of humor.

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