Physical Society Colloquium

Special Colloquium

Jim Cronin
Nobel Laureate

University of Chicago

James W. Cronin, professor of physics at the University of Chicago, received a Ph.D. in physics from the University of Chicago in 1955. He served as assistant physicist at Brookhaven National Laboratory from 1955 until 1958, when he accepted an appointment as assistant professor of physics at Princeton University. He became professor of physics at Princeton in 1964. In 1971, he returned to the University of Chicago as professor of physics. Dr. Cronin's many awards include the Nobel Prize, which he received in 1980 with physicist Val L. Fitch, for their discovery of charge conjugation/parity violation, the asymmetry in the behavior of matter and antimatter. Dr. Cronin is a member of the National Academy of Science and the American Academy of Arts and Science; he is a fellow of the American Physical Society.

Report on the Pierre Auger Cosmic Ray Observatory:
A Detector 30 Times the Size of Paris

Each second, about 200 cosmic ray particles with energies of a few million electron volts strike every square meter of the earth. While these low-energy cosmic rays are plentiful, cosmic rays at higher energies are far rarer. Above the energy of 10¹⁸ eV, only one particle each week falls on an area of one square kilometer. Above the energy of 10²⁰ eV, only one particle falls on a square kilometer in a century! To find and measure these rare events, a high-energy cosmic ray study needs a truly giant detector. The Pierre Auger Cosmic Ray Observatory is such a detector.