Balloon flight re-creates history at Snowmass, July 8

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BATAVIA, Ill.—Physicists, often regarded as having their heads in the clouds, will take their stereotype literally during an aerial experiment in the early morning of Sunday, July 8 at Snowmass, Colorado when they lift off in a hot-air balloon to re-create the 1912 discovery of cosmic rays by Austrian physicist Victor Hess.

Launched from the Snowmass Rodeo Grounds at 6 a.m., the balloon flight represents a highlight of “Science Weekend” during the three-week conference “Snowmass 2001: A Summer Study on the Future of Particle Physics,” sponsored by two divisions of the American Physical Society. The flight also launches a weeklong workshop (July 16-21) for Snowmass-area high school teachers and students, preparing them to participate in a cosmic ray experiment that will also involve schools throughout North America.

SALTA (Snowmass Area Large-scale Time-coincidence Array) will set up a cosmic ray detector network in collaboration with five high schools, including Wheaton North High School in Illinois and four in the Snowmass area: Aspen High School, Basalt High School, Roaring Fork Valley High School in Carbondale and Lake County High School in Leadville. SALTA will link up with four other arrays in a continent-wide network of high school and college students in California (CHICOS), the Midwest and South (CosRayHS), Nebraska (CROP), Seattle (WALTA) and Edmonton, Canada (ALTA). The SALTA project is made possible by an anonymous benefactor and the cooperation of Fermilab.

“This is a real science experiment, not a toy,” says SALTA co-director Greg Snow, a physicist at the University of Nebraska at Lincoln and a Fermilab experimenter. “The equipment is coming from a world-class cosmic ray experiment called CASA (Chicago Air Shower Array), which ran for almost nine years in Utah and was retired in 1998. The leader of the CASA experiment was James Cronin, who won the Nobel Prize for Physics in 1980.”

During the SALTA workshop, student-teacher teams (usually one physics teacher and three students from each school) will learn to use the detector equipment and other instruments, such as oscilloscopes. They’ll train in using high-voltage power supplies. They’ll attend talks from leading researchers on the physics of cosmic rays, along with the principles of particle accelerators and collider detectors.

“We want to emphasize that they’re all participating in a bona fide cosmic ray experiment, making real measurements, with potentially publishable results,” Snow says, adding that previous workshops in Nebraska have led students and teachers to “embrace the project, carving out time in their classes, before school and after school to conduct their research and send reports to us.”

Cosmic rays are among the many kinds of radiation reaching the top of the earth’s atmosphere from outer space. Cosmic rays provide scientists with information on violent, energetic processes in distant stars, allowing them to study the fundamental particles and forces of nature under conditions far beyond the reach of man-made particle accelerators. The highest-energy cosmic rays reach energies a million times as great at Fermilab’s Tevatron, the world’s highest-energy particle accelerator.

Victor Hess (1936 Nobel Prize) proved the existence of cosmic rays during a balloon flight launched from Northern Bohemia on August 7, 1912, that reached an altitude of nearly 17,500 feet. Bringing aloft the current state-of-the-art equipment in radiation measurement, the “electroscope,” his data showed radiation levels increasing with altitude. Hess concluded that “a radiation of very high penetrating power enters our atmosphere from above,” from what we now call outer space.

“In any talk, lecture or book about cosmic rays, you’ll encounter the name of Victor Hess,” Snow says. “This was a pivotal measurement in the last century’s research on cosmic rays. We’ll try to re-enact the Victor Hess flight as well as we can.”

Snow plans to staff the ground station, receiving information from SALTA co-director and University of Washington physicist Jeff Wilkes, who will be costumed in 1912 fashion.

“I’ve already made arrangements with the University of Washington Drama Department to check out a period costume, complete with Austrian naval officer’s cap, which contemporary photos show Hess wearing,” Wilkes said. “He will go aloft with present-day cosmic ray detector equipment as well.”

“Snowmass 2001” represents a unique opportunity to gain new insights into the world around us. To arrange coverage of this world-class science gathering, visit the Web at

Fill out the registration form, and submit it electronically; or print it and fax it to Fermilab’s Office of Public Affairs at 630-840-8780.

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Fermilab, offering organizational and logistical support for Snowmass 2001, is operated by Universities Research Association, Inc., under contract with the U.S. Department of Energy.