Reuven Ramaty, a pioneer in high-energy astrophysics and a leading theorist at NASA’s Goddard Space Flight Center for more than 30 years, died on 8 April 2001 at his home in Silver Spring, Maryland, of complications from Lou Gehrig’s disease. The inveterate scientist, he remained active in his research until his final moments, poring through data on cosmic rays just hours before he died.
Born on 25 February 1937 in Timisoara, a Hungarian section in Romania, Reuven grew up on the eve of World War II in a multicultural environment and immigrated to Israel at age 11. A lover of language, as a true scholar, he became fluent in Hebrew, English, and French in addition to his native Romanian and Hungarian; he also studied German, Italian, and Japanese. He graduated from Tel Aviv University in 1961 with a BSc in physics. He then moved to the US, where he earned his PhD in planetary and space physics from UCLA in 1966.
Reuven joined Goddard in 1967, first as a postdoctoral research associate, and then as a government-employed astrophysicist at the Laboratory for High Energy Astrophysics in 1969. From 1980 to 1993, he was the head of the theory office at the lab. His studies of gamma-ray data from the COS-B, SAS-II, and HEAO-C missions during the 1970s and 1980s guided the development of the highly successful Compton Gamma Ray Observatory (CGRO). Reuven was a major influence in the success of the Solar Maximum Mission (SMM), and colleagues have pointed out that NASA’s HESSI mission, which is expected to be launched in late 2001, might not have been realized without his active encouragement and involvement.
Reuven’s scientific impact spread across solar-flare physics, gamma-ray astronomy, and cosmic rays has been profound. The study of high-energy nuclear reactions in solar flares and the use of gamma-ray line and neutron measurements to determine the properties of flare-accelerated particles were essentially invented in the 1960s by Reuven and one of us (Lingenfelter), his longtime colleague. In later expanded collaborations, including Benz Kozlovsky of Tel Aviv University and others, Reuven continued to refine these techniques over the next 30 years through extensive studies of flares observed by SMM and CGRO to probe particle acceleration mechanisms and both accelerated particle and coronal abundances. With Len Fisk of the University of New Hampshire and Kozlovsky, Reuven further proposed the now generally accepted origin of low-energy anomalous cosmic rays from the ionization and acceleration of neutral interstellar gas in the outer heliosphere.
Ramaty and Lingenfelter also pioneered the field of gamma-ray-line astronomy with seminal studies of positron annihilation radiation, nuclear deexcitation lines, and nucleosynthetic decay lines in the interstellar medium and compact sources. Those studies were summarized in their review article “Gamma Ray Lines: A New Window to the Universe” (Physics Today, March 1978, page 40). The most notable of those studies was their prediction of interstellar gamma-ray emission in the 1.809-MeV line from the decay of supernova-produced aluminum-26, which was subsequently found with instruments on HEAO-C in 1982 to be the most intense nucleosynthetic line in the Galaxy.
More recently, Ramaty, Lingenfelter, and Kozlovsky showed that observations of the abundances of cosmic-ray-produced beryllium and boron in early stars required that the cosmic rays had to be accelerated in high-metallicity material and not out of the average interstellar medium, as was generally supposed. This work was presented in physics today in an article entitled “Cosmic Rays, Nuclear Gamma Rays and the Origin of Li, Be and B” (April 1998, page 30).
Seeking intellectually stimulating travel, Reuven was a visiting professor at Nagoya University in Japan in 1993 and a member of the PhD dissertation committee at the University of Paris and the Pierre and Marie Curie University in Paris in 1992 and 1997, respectively. He was also a visiting scientist at Caltech, Stanford University, the University of California (Berkeley and San Diego), the University of Pennsylvania, and Washington University in St. Louis, Missouri. Reuven also was an adjunct professor of physics at the University of Maryland, College Park, from 1983 until his death. He served as an associate editor of Physical Review Letters (1974-77); chair of the American Physical Society’s division of astrophysics (1977-78); chair of the American Astronomical Society’s high-energy astronomy division (1984-85); and the APS divisional councillor for astrophysics (1986-89).
It was Reuven’s habit and style to make every minute count, not just in his terminal days, but throughout his life. He strove to find new experiences everywhere he went. Reuven’s activities went beyond science and languages to include interests as diverse as piano and poker. He also was a devoted family man.
One week before his death, Reuven was notified that he was the winner of the 2001 Yodh Prize, given by the Commission on Cosmic Rays of the International Union of Pure and Applied Physics (see Physics Today, October 2001, page 86). He also won the Senior US Scientist Award from the Alexander von Humboldt Foundation in 1975.
Reuven will be greatly missed by his many friends and collaborators.
