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Caltech News Release
Contact: Mark Wheeler
        (626) 395-8733
        wheel{at}caltech.edu

For Immediate Release
January 27, 2003

Caltech Partners with Local High Schools to Measure Subatomic Shrapnel

PASADENA, Calif. - They stream out of deep space, traveling at speeds 
close to that of light, constantly bombarding Earth and literally 
passing through our bodies: subatomic shrapnel, as one magazine 
described them, energetic bits of matter known as cosmic rays.

For the past year, Los Angeles-area high school students and their 
teachers have teamed up with a Caltech physicist to, in a sense, 
"catch" these ultrahigh-energy rays on their own campuses. Students 
and their science teachers from the Pasadena Unified School District, 
Los Angeles Unified School District, and other districts in Southern 
California, have been involved in the development and construction of 
detector hardware, the associated electronics, and the computer 
equipment to form a networked system among 30 Southern California high 
schools. The project is called the California High School Cosmic-Ray 
Observatory (CHICOS). Ultimately, says Caltech physics professor 
Robert McKeown, at least 90 detectors will be installed, scattered 
widely throughout Southern California.

A large array of detectors will enable the study of these 
ultrahigh-energy cosmic rays through the detection of "showers," 
several kilometers in radius, of secondary particles they create in 
the Earth's atmosphere. Such rays are the highest-energy particles 
ever observed in nature and have captured the fancy of the 
astrophysics and particle-physics community. Thus, while establishing 
a state-of-the-art experimental facility, the project is also 
providing an exceptional educational experience for local high school 
students. When a majority of the sites are operating, McKeown expects 
the project will yield enough significant science to be reported in 
the scientific journals.

Cosmic rays are comprised of protons, neutrinos (uncharged elementary 
particles), gamma ray photons (bits of light emitted spontaneously by 
a radioactive substance), and other subatomic "stuff." They are of 
interest to scientists for a couple of reasons. For one, studying 
their composition tells how the galaxy has continued to evolve 
chemically since the solar system was formed. This helps us to 
understand how the solar system got the chemical composition that it 
has, and, in turn, tells us something about our origin. Further, as 
energetic as they are, cosmic rays may emanate from cataclysms of 
staggering proportions, including the Big Bang, shock waves from 
supernovas collapsing into black holes, and matter that's accelerated 
as it is sucked into massive black holes. Knowing where these 
particles originate and how they attain such colossal energies will 
help scientists understand how these violent objects operate.

"The idea is, 'what do these things point back to?' " says McKeown. 
"And, can we learn something about where they come from as a result of 
that? This is real science. Maybe these things will point back to some 
exploding object in the sky, which is exciting to kids. And to me, for 
that matter."

The timing of when the showers hit the different schools is what tells 
scientists like McKeown a lot about where they came from. The cosmic 
rays will generate a "pancake" of rays that, as it falls, gets bigger 
and bigger. The particles will hit one detector first, then another 
one sometime later. The detectors at the center of the shower will 
have stronger signals than the detectors farther away.

Once the center of the shower is detected, the direction of the shower 
can be determined from the relative times. This is where the high 
school kids come in--using trigonometry, they can reconstruct the 
direction of the showers, taking into account the orientation of the 
earth at that time.

The program also incorporates a high-school-teacher education 
component coordinated by Dr. Ryoichi Seki at California State 
University, Northridge. Teachers are developing curriculum materials 
to help their students participate in this research. Caltech also 
hosts a summer workshop where physics teachers and students can 
participate in the construction of new detector stations for 
deployment at additional sites.

"One of the things I like to show the students and teachers is that 
this really is a current and ongoing research project," says McKeown, 
"so it's not an exercise out of a textbook but real science."

For more information on CHICOS, please see 
http://www.chicos.caltech.edu/.

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