A 12 meter wide acrylic vessel, now filled with a thousand tons of heavy water, is at the core of the SNO experiment. Surrounding the vessel, mounted on a geodesic steel support structure, are the photomultiplier tubes which will record neutrino events.

To shoot his steel and acrylic prey, Lab photographer Roy Kaltschmidt (pictured here in a self portrait) was lowered deep into SNO's acrylic cavity, where he was surrounded by thousands of photomultipliers. "You feel like you're in the middle of the Milky Way, with stars blinking all around you," he said.

It may look like the eye of a giant reptile, but in fact it is an ambitious scientific experiment to unravel the mysteries of one of the most common yet most elusive particles in the universe—the neutrino.

Built two kilometers under solid rock in a cavity the size of a 10 story building, the Sudbury Neutrino Observatory (SNO) involves an international collaboration of 70 scientists from the U.S. (including Berkeley Lab), Canada, and Great Britain. Shielded from interference with ubiquitous cosmic rays, the experiment will allow scientists to observe the tiny bursts of light that take place when neutrinos collide with other particles.

Such observations will help them better understand the nature of the neutrino, and perhaps even answer some questions about dark matter and missing mass in the universe. Berkeley Lab's Kevin Lesko, a nuclear scientist, is the project leader for the Lab's portion of the SNO experiment.

Research Review Fall '98 Index | Berkeley Lab