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William L. Kraushaar

Professor William L. Kraushaar, a former MIT physics professor and a pioneer in the field of high-energy astronomy, died March 21 of complications from Parkinson’s disease. He was 87.

Kraushaar received his bachelor degree from Lafayette College in 1942. During World War II he worked at the National Bureau of Standards on projects that included development of the proximity fuse for artillery shells. After the war he earned his doctorate at Cornell University. In 1949 he was appointed research associate at MIT where he made the first measurements of the mean life of the pi meson at the MIT electron synchrotron. Over the next 15 years he rose through the faculty ranks, becoming a full professor before leaving MIT for the University of Wisconsin at Madison in 1965.

In 1957 Kraushaar began a decade-long effort to map the sky in the “light” of cosmic gamma rays. Their detection promised to open new ways to investigate high-energy processes in the universe. Initial balloon-borne experiments failed due to background gamma rays generated in the residual atmosphere above the highest attainable altitudes.

In 1958, Kraushaar seized the new opportunity for experiments above the atmosphere. Working with Professor George W. Clark PhD ’52, he directed the development in the MIT Laboratory for Nuclear Science of a gamma-ray detector for a satellite experiment that was launched in April 1961 as Explorer 11. It registered 31 events with the electronic signatures of cosmic gamma rays with energies greater than 50 MeV. Kraushaar then initiated a second and more refined experiment to be carried on OSO 3.

In this project Kraushaar and Clark were joined by Gordon Garmire PhD ’62, a former student of Kraushaar. The OSO 3 experiment, launched in March of 1967, registered 621 cosmic gamma ray events. It yielded the first all-sky map of high-energy cosmic gamma rays showing a concentration of gamma rays from directions in the Milky Way where gamma-ray producing interactions of charged cosmic rays with interstellar matter are most abundant. It also demonstrated the existence of extra-galactic gamma ray sources that have since been identified as giant black holes at the centers of distant galaxies. The OSO 3 experiment opened the field of high-energy gamma-ray astronomy, which has become one of the most active areas of space research.

Upon his move to Wisconsin, Kraushaar established a research group in the new area of X-ray astronomy. Using instruments flown on “sounding” rockets, he and his colleagues produced the first all-sky map of low-energy X rays that revealed the spatial distribution of million-degree interstellar gas. They extended these results in several satellite experiments. Kraushaar was appointed the Max Mason Professor of Physics in 1980.

Kraushaar was a fellow of the American Physical Society, and a member of the American Astronomical Society, the International Astronomical Union, the National Academy of Sciences, and the American Academy of Arts and Sciences. He received Fulbright and Guggenheim fellowships and the Senior Scientist Award of the Humboldt Foundation. He served on numerous advisory committees of the National Academy of Sciences and NASA. He co-authored with Professor Uno Ingard a college text, “Introduction to Mechanics, Matter, and Waves.”

After his retirement, Kraushaar moved to Maine where he resided in Scarborough with summers at his cabin in Denmark, Maine. He is survived by his wife, the former Elizabeth Rodgers, and by three children from his first marriage.