Cosmic rays and their lessons about the universe

Physicist Lucy Fortson will present the series, titled "Astronomy With Particles: How the Study of Cosmic Rays Became Astroparticle Physics." The lectures will focus on cosmic rays and the various tools astrophysicists use to determine their origins.

"Cosmic rays are charged particles that we think are produced by a variety of astrophysical phenomena -- for example, the sun and supernovae," Fortson said. "But because most cosmic rays are charged, they interact with magnetic fields as they zip around the Universe, and it's very difficult to tell where they originally came from."

Cosmic rays are ubiquitous invaders from outer space, raining down onto the earth's atmosphere in a continuous stream of charged particles. Fortson will talk about the discovery of cosmic rays and the variety of space- and ground-based experiments that have been used to detect them, including a proposed giant array that would cover an area the size of the state of Rhode Island, called the Pierre Auger Project, planned for two sites in North and South America. The Pierre Auger Project, led by James Cronin, University Professor Emeritus in Physics, will be able to detect the highest-energy cosmic rays, which may come from remnants of the Big Bang.

Fortson, who runs a University cosmic-ray experiment in Dugway Proving Grounds, Utah, received her B.A. in physics from Smith in 1984 and her Ph.D. in physics from UCLA in 1991. She is currently a Research Associate in the Enrico Fermi Institute.

The talks are the 45th series of Arthur Holly Compton Lectures sponsored each fall and spring by the Enrico Fermi Institute. Arthur Holly Compton was a University physicist and a Nobel laureate best known for demonstrating that light has the characteristics of both a wave and a particle. He was also a member of the research team that in 1942 produced the world's first controlled, self-sustaining nuclear reaction.

The lectures are intended to make science accessible to a general audience and to convey the excitement of new discoveries in the physical sciences. Previous topics have ranged from the smallest fundamental particles of matter to the history of the Universe.

The Compton Lectures are free and open to the public. See the Calendar for lecture topics; for more information, call 7027823.