Bruno Rossi, 88, Pioneer in Cosmic Ray Research

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by Wolfgang Saxon

THE NEW YORK TIMES OBITUARIES

Wednesday, November 24, 1993

Dr. Bruno Rossi, an authority on cosmic rays and a retired professor of physics at the Massachusetts Institute of Technology, died on Sunday at his home in Cambridge, Mass. He was 88.

The cause was cardiac arrest, M.I.T. said.

Much honored for his own explorations, Dr. Rossi had a hand in the development of space physics and in shaping public policy for space exploration. His investigations of cosmic rays and their interactions with matter laid the foundation for high-energy particle physics.

Cosmic rays are atomic particles that bombard Earth's atmosphere from space at speeds approaching that of light.

Professor Rossi came to M.I.T. from the Los Alamos Laboratory in 1946 as a professor of physics. In 1966 he was named Institute Professor, a rank reserved for scholars of special distinction. He retired in 1971.

`One of the Giants'

Prof. Claude R. Canizares, director of M.I.T. Center for Space Research, Dr. Rossi's old workplace, called him ``one of the giants of modern physics and astrophysics.''

He said that even before joining M.I.T., Professor Rossi had made ``seminal contributions'' and invented basic experimental techniques used in every major laboratory to this day. At M.I.T. he ``opened new windows on the universe,'' he added.

``He is rightfully called the grandfather of high-energy astrophysics, being largely responsible for starting X-ray astronomy as well as the study of interplanetary plasma,'' Professor Canizares said. And he called Professor Rossi's textbooks models of clarity.

Professor Rossi was the author or co-author of seven books and more than 100 technical articles. His autobiography, ``Moments in the Life of a Scientist,'' was published by Cambridge University Press in 1990. As a teacher, he inspired leaders in higher learning and industry.

Dismissed by Fascists

Bruno Benedetto Rossi was born in Venice, the son of an electrical engineer. He studied at the University of Padua and received his doctorate in physics at the University of Bologna in 1927. He started his academic career at the University of Florence and held the chair in physics in Padua from 1932 to 1938, when the Fascist regime dismissed him.

He then spent short periods in Copenhagen; Manchester, England; and Chicago, and joined the faculty of Cornell University in 1940. From 1943 to 1946 he was on the staff of the Los Alamos Laboratory in New Mexico, where the atomic bomb was developed.

Dr. Rossi's career paralleled the evolution of cosmic-ray physics. He ventured into that mysterious field in 1929. That year he devised the first of the instrumental techniques he contributed to astrophysics.

Known as the Rossi coincidence circuit, it recorded the simultaneous occurrence of three or more electrical pulses. It became a fundamental electronic device for experimental high-energy nuclear physics and a basic element of modern computers.

In 1931 he discovered that cosmic-ray particles,thought rapidly losing energy, could pass through enormous thicknesses of matter --- up to a meter of lead. He also discovered that individual cosmic rays, colliding with atoms, often generated large numbers of secondary particles, known as showers. His findings gave evidence of the astonishing energies associated with cosmic rays.

His interest in this bombardment from space led him into space research as the technical means for placing instruments outside the Earth's atmosphere became available. In 1958, for instance, he focused attention on direct measurements of ionized interplanetary gas by space probes.

He and his colleagues built a detector with which the Explorer X satellite in 1961 discovered the magnetopause, the space boundary beyond which Earth's magnetic field loses its dominance. He also initiated the exploratory search for cosmic x-rays that in 1963 resulted in the discovery of the strong Scorpio X-ray source, the first such source to be observed outside the solar system.

The discovery marked the beginning of X-ray astronomy, which soon became a principal tool of astrophysics research.

Dr. Rossi was a member of many scientific societies, including the National Academy of Sciences and American Academy of Arts and Sciences. His honors included the United States Medal of Science, the Gold Medal of the Italian Physical Society, the Elliot Cresson Gold Medal and the Wolf Prize in Physics.

Dr. Rossi is survived by his wife Nora Lombroso Rossi; two daughters, Florence Moloney of Sunnyvale, Calif. and Linda Rossi of Manhattan; a son Frank of Boston, and two grandchildren.