Cosmic Ray News Bulletin


Author: Frank C. Jones
Laboratory for High Energy Astrophysics, Code 661
NASA/Goddard Space Flight Center
Greenbelt, Maryland 20771, USA
Tel: 1-301-286-5506
Fax: 1-301-286-1682
(Back Issues are available)





  •                 A. E. CHUDAKOV

                    REUVEN RAMATY


     The 27th ICRC is scheduled for August 7 - 15, 2001 in Hamburg, Germany. Their WEB page is now up and running at: Logo

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    New Awards

    In addition to the well-established and successful Shakti P Duggal award for young researchers, the 26th ICRC saw the first presentation of the newly established O'Ceallaigh medal and the announcement of one further award, the Yodh Prize. 

    The O'Ceallaigh medal is awarded by the Commission for "Distinguished Contributions to Cosmic Ray Research" and commemorates the late Professor Cormac O'Ceallaigh (1912-1996) who was head of the Cosmic Ray Section of the Dublin Institute for Advanced Studies from 1953 until 1984. As a young man he spent a year working in the laboratory of Pierre Auger in Paris, but his most productive period began when he worked in Cecil Powell's group in Bristol in the late forties. During this period he did important work on what would now be called Kaon and neutrino physics using the nuclear emulsion technique. His subsequent work was mainly on developments of the solid state track detector technique for determining the ultraheavy element abundances in the cosmic rays, work which is just now coming to fruition with results being reported by his former colleagues at Salt Lake City from the DIAS/Estec Ultra-heavy Cosmic Ray Experiment. 

    The Commission had a difficult task in deciding to whom to award the first O'Ceallaigh medal. It is clear that when an award like this is first instituted there will inevitably be a number of excellent candidates who would probably have received the award in earlier years had it existed. In this case two names rapidly emerged from those suggested as clear favourites, both in their own very different ways excellent canididates.  The Commission eventually decided that the correct course of action was to award the 1999 medal jointly to John Simpson from Chicago and George Zatsepin from Moscow. Between them they have made seminal contributions to essentially all areas of Cosmic Ray Research, from the solar and Geomagnetic effects studied with Simpson's neutron monitors to the ultra-high energy and probably extragalactic particles seen beyond the Greissen-Zatsepin-Kuzmin cut-off. Each has been an inspiration to generations of students and colleagues and it is fitting that their contributions be recognised formally by the community to which they have given so much. 

    A. E. Chudakov

    Aleksandr Evgenievich Chudakov, an outstanding Russian scientist in the field of cosmic ray physics passed away on January 25, 2001 at an age of 79.

    A.E. Chudakov was born on June 16, 1921. He entered the Moscow State University in 1939, but, due to an interruption caused by the World War II, was graduated from it only in 1948. However, he started his scientific carrier under supervision of S.N. Vernov while being a student. In 1947-1951, in a series of experiments with rockets, he measured the intensity of cosmic rays beyond the atmosphere. Studying the generation of electron-photon component by protons in thin lead plates, it was shown in these experiments (two years prior to the discovery of neutral pions) that a meson responsible for generation of electrons and photons has a lifetime of less than 10-9 s.

    In 1953, he was the first to confirm experimentally the existence of the transition radiation predicted by V.L. Ginzburg and I.M. Frank in 1945, and in a series of papers of 1953-1960 he studied the transition radiation at optical wavelengths in great detail. In one of his early papers (1955) he had predicted the effect of decreasing ionization losses for narrow electron-positron pairs, later referred to by many scientists as the Chudakov effect. Much later it became clear that the effect has, in a sense, universal character and, for example, reveals itself in QCD as a screening of color charges of narrow quark and gluon pairs. 

    In the years 1953-1957 Chudakov carried out a series of experiments in the Pamir mountains studying Cherenkov emission of extensive air showers in the atmosphere. The next cycle of investigations of cosmic rays outside the atmosphere was carried out by Chudakov together with S.N. Vernov in first satellite experiments (1957-1959), which resulted in discovery of the outer Earth's radiation belt during the third Soviet sputnik flight.

    As long ago as in 1959 A.E. Chudakov constructed a big water Cherenkov detector with a mass of 100 t (this detector can be considered as an early ancestor of giant modern water Cherenkov detectors like Superkamiokande). In 1961, in a paper by G.T. Zatsepin and A.E. Chudakov the method of Cherenkov gamma ray astronomy was suggested (a new branch of astronomy has now been developed from this paper). This method was immediately implemented by Chudakov and his collaborators in a pioneering experiment on gamma ray astronomy at Katsively, Crimea. This first experiment was finished in 1963, and its negative result was, nevertheless, quite important in the case of the Crab Nebula, the upper limit obtained being a proof of direct acceleration of electrons in this source.

    Since 1963, when a decision to start the construction of the Baksan neutrino observatory had been made, professor Chudakov was fully involved in this task. The creation of the Baksan underground scintillation telescope (put into operation in 1978) was accomplished under his general supervision, starting from the general philosophy of experiments and including minute details of construction (he was a very rare type of a person who had simultaneously an acute intuition in theoretical problems and a great talent in engineering and electronics). The Baksan telescope was one of the first (if not first) large multi-purpose facilities of underground physics, and a handful of first-class results in the field of elementary particle physics, physics of cosmic rays, and neutrino astrophysics were obtained with this instrument which is still in operation. At the same time professor Chudakov initiated the construction of the Carpet and Andyrchi air shower arrays at Baksan, thus making this place a center of cosmic ray studies with the unique set of facilities.

    The ideas of professor Chudakov were multifarious. In 1974 he suggested to record the Cherenkov emission of giant air showers reflected from snow by using airplane-born optical detectors (though some attempts were made, this idea still waits for proper experimental realization). He was also first who nominated the lake Baikal as the best place for underwater neutrino detector (the only operating underwater telescope NT-200 has been constructed there).   

    A.E. Chudakov was unquestionably one of the leading persons in cosmic ray science of the second half of the past century, and his name belongs to its history. As a professor of Moscow University he educated many young scientists. Being at first a secretary and then a chairman of the IUPAP Commission on Cosmic Rays, he was widely known and highly respected in the world cosmic ray community. His death is a great loss for his friends and colleagues.     

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    Reuven Ramaty

    Reuven Ramaty, a renowned expert on cosmic rays, gamma rays and nuclear astrophysics and a leading theorist at NASA's Goddard Space Flight Center, Greenbelt, Md., for over 30 years, died April 8 at his home in Silver Spring, Md., of complications from amyotrophic lateral sclerosis (often called Lou Gehrig's disease). He was 64 years old.

    Only a week before his death, Ramaty was notified that he was the recipient of the first Yodh Prize to be formally presented in August at the 27th International Cosmic Ray Conference in Hamburg.  He remained active in his research until his final moments, working on a paper with colleagues on the day he passed away. He is survived by his wife, Vera, his two daughters, Daphne and Deborah, and five grandchildren.

    Ramaty's contributions to the fields of solar physics and cosmic rays are enormous, reflected in his 160 publications in refereed journals and conference proceedings and more than 5,000 citations to his work in the open literature. Ramaty was also the principal investigator on four NASA-funded theory initiatives and a co- or guest investigator on several space-science missions.

    The field of positron astrophysics -- the study of gamma rays produced by matter-antimatter annihilation -- was essentially invented by Ramaty and his longtime colleague, Richard Lingenfelter of the University of California, San Diego. Ramaty and Lingenfelter were also key in establishing the field of solar gamma-ray-line astronomy, a technique used for establishing the abundance of elements in the sun as well as determining how sun flares are produced.

    Born in Timisoara, an ethnic Hungarian section in Romania, Ramaty grew up on the eve of World War II in a multicultural environment and immigrated to Israel at age 11. Fluent in Hungarian, Romanian, Hebrew, English and French, Ramaty graduated from Tel Aviv University in 1961 and moved to the United States, where he earned his doctorate degree in Physics from the University of California, Los Angeles, in 1966.

    Ramaty joined NASA's Goddard Space Flight Center first as a post-doctoral research associate in 1967 and then as a government-employed astrophysicist at Goddard's Laboratory for High Energy Astrophysics in 1969. From 1980 to 1993, Ramaty was the head of the Theoretical High Energy Astrophysics Office at the Laboratory.

    Through the 1970s and 1980s, Ramaty's interpretation of gamma-ray data from the COS-B, SAS-II and HEAO-C missions guided the development of the highly successful Compton Gamma Ray Observatory. Ramaty was a major influence in the success of the Solar Maximum Mission, as well, and colleagues say that his active encouragement and involvement was instrumental to the realization of NASA's upcoming HESSI mission.

    A lover of language and travel, Ramaty was a visiting professor at Nagoya University in Japan in 1993 and a member of the Ph.D. dissertation committee at the University of Paris and the Pierre & Marie Curie University in Paris in 1992 and 1997, respectively. He was also a visiting scientist at Caltech, Stanford University, University of California (Berkeley), University of Pennsylvania, and Washington University in St. Louis. As Adjunct Professor of Physics at the University of Maryland since 1983, Ramaty was the advisor for several  Ph.D. recipients.

    Ramaty also served the high-energy astronomy community in a variety of other positions, including Associate Editor of Physical Review Letters; Chair of the American Physical Society Division of Cosmic Physics; Chair of High-Energy Astrophysics Division of the American Astronomical Society; and Divisional Councilor for Astrophysics at the American Physical Society. 

    On December 11, 2000, friends organized a symposium in his honor entitled, "A Tribute to Reuven Ramaty's Contributions to High-Energy Solar Physics and Astrophysics." The meeting presenters described the current state of scientific exploration that was inspired or otherwise guided by Ramaty's lifetime of achievements.

    Christopher Wanjek

    Item Entered May 8, 2001

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