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NASA grant to aid in cosmic ray research

A cosmic ray shower occurs in an instant, but analyzing it can take days of computer time with ordinary processors. Steve Stochaj, director of the Particle Astrophysics Laboratory at New Mexico State University, aims to cut that time dramatically by custom-building a parallel computer system that offers supercomputing capabilities at a fraction of the cost.

Stochaj and two NMSU doctoral students will use a NASA grant totaling about $158,000 over two years to build the system and develop the software to simulate cosmic ray "events" -- the interactions of high-energy cosmic rays with matter.

The project will not only facilitate the cosmic ray research of Stochaj and his colleagues, it will also give NMSU students opportunities for hands-on experience in the emerging field of parallel computing. And the simulation software will be made available free to other cosmic ray researchers worldwide.

Cosmic rays are subatomic particles from space that constantly bombard the earth. Where they come from and how they accelerate to their high energy levels are matters of speculation, but learning more about them is important to understanding the structure and evolution of the universe, Stochaj said.

When a cosmic ray particle comes into the earth's atmosphere, "the primary particle creates a tremendous number of secondary particles," Stochaj said. These "air showers" vary with different types of particles -- nuclei, protons, antiprotons, electrons and positrons -- and other factors such as the particle's energy level.

When one of these events is measured by a cosmic ray detector, analyzing it requires comparing it to "a huge library" of simulations to find one that matches, Stochaj said. "To get 50 simulations can take a week" using ordinary computers, he said. "We're hoping to get 50 in a day" with a parallel processing system known as a Beowulf-class computer cluster.

In simplified terms, with parallel processing "you take a really big problem and distribute pieces of it among a lot of PCs (personal computers) and then you assemble the answer," Stochaj said. The alternative, a supercomputer, is much more expensive, he noted. "A hundred thousand dollars buys nothing in the supercomputer world, but it buys a lot of PCs. We are using off-the-shelf computers to do parallel computing."

The system will use processors with Alpha chips, which can handle larger segments of data than the Pentium-based processors that many PCs use, he said. The processors will be coupled together with special message-passing hardware and software that will enable complex computational workloads to be divided among the processors.

Tom Stephens, a doctoral student in astronomy, and Will Dearholt, a doctoral student in electrical and computer engineering, will be instrumental in setting up the system and developing the software code to run the complex simulations using parallel processing.

"Programs don't automatically parallel themselves," Dearholt said. "You have to design algorithms and make sure the data goes from processor to processor correctly."

Other students, including undergraduates, also will participate in the program, and the computer cluster will be available for other uses when it is not being used for cosmic ray research. "We hope it will never be idle," Stochaj said.

One of the purposes of the grant, awarded by NASA's Minority University Research and Education Division, is to help recruit more minority students into science and engineering fields. With a student enrollment that is about 39 percent Hispanic, NMSU is designated as a Hispanic Serving Institution by the federal government.

The Particle Astrophysics Laboratory, a unit of the NMSU College of Engineering, is engaged in cosmic ray research on several fronts, and all rely heavily on computer modeling. PAL is a participant in the Milagro ground-based gamma ray observatory near Los Alamos, funded by the National Science Foundation. A PAL project is one of only two being considered by NASA for the Advanced Cosmic-ray Composition Experiment on the Space Station (ACCESS), which will study cosmic rays in space where they are unaffected by the earth's atmosphere. In addition, the laboratory regularly launches huge helium-filled balloons that carry scientific payloads to altitudes of about 120,000 feet to observe cosmic rays before they interact with the earth's atmosphere.

The parallel computer system will boost all of these efforts to better understand the nature and origins of cosmic rays.