A balloon with about 36 antennas will be flown over Antarctica next year by a University of Hawaii-Manoa physicist in a test to try to detect neutrinos with a billion trillion volts of energy. UH project tries to
solve mystery of neutrinos
By Helen Altonn
haltonn@starbulletin.com"We hope to make the very first measurements of super-high-energy neutrinos ever detected," said Peter Gorham, associate professor of physics.
If the test is successful, he hopes to fly a balloon over the Antarctic continent in the Austral summer of 2006 to find "unusual snaps" associated with neutrino lightning bolts.
NASA and other groups are supporting his five-year, $8 million project called ANITA (Antarctic Impulsive Transient Antenna).
Neutrinos are invisible elementary particles raining on Earth from cosmic rays that are detected only by their interactions.
Lightning produces very strong radio pulses, and its "crackle and pop" can be heard on FM radio from miles away in the Midwest, Gorham pointed out.
"The same is true for neutrino events. They come along happily in rock and interact and produce mini lightning bolts."
Water doesn't transmit radio waves well but ice, rock salt and granite are good propagators, Gorham said.
"I don't think anyone will let us put antennas on El Capitan or Yosemite, so the focus is how we can put radio antennas near large bodies of ice or rock salt and hope to detect some of these neutrino interactions."
His long-time collaborator, David Saltzberg of UCLA, is focusing on salt domes in a complementary approach to detecting neutrinos from high energy cosmic rays, Gorham said.
Gorham, who joined UH last fall from the Jet Propulsion Laboratory, recently was awarded the elite Outstanding Junior Investigator award by the U.S. Department of Energy High Energy Physics Division.
Only about six such awards are given annually, usually to scientists at such institutions as Harvard, MIT, Cornell or Johns Hopkins University. Saltzberg was a previous recipient.
He will receive about $80,000 a year as part of the award until he receives tenure, then the money will be folded into the UH High Energy Physics Group's base grant, he said.
The ANITA project is focused on neutrinos with such high energy that "it's almost inconceivable," Gorham said. "A billion trillion volts. It's still a subatomic particle so it wouldn't produce anything we would ever notice."
But as the particles enter atmosphere from space and interact with air molecules, producing pions, muons and electrons, a very faint flash of light is produced like a meteor shower, he said.
Physicists have known about these ultra-high energy cosmic rays since the 1960s, he said, but "we don't know of anything that can produce them."
Wherever they're being made, he said, "They can't travel very far and will end up converting into neutrinos in a short time through intergalactic space. So we have kind of a double mystery."
Besides not knowing where they're coming from, there aren't enough energy sources close to our galaxy to produce them, he said.
"So the mystery is compounded by the problem of how do these things propagate once they're formed? If they interact, where are the neutrinos produced by them?
"Neutrinos are almost guaranteed to be there if we can figure out how to detect them," Gorham said.
The balloon in his experiment will fly at an altitude of about 25 miles, seeing an enormous amount of ice, Gorham said. The antennas will be very sensitive to radio waves from all the ice beneath the balloon out to the horizon, almost 434 miles away, he said.
The balloon will float over the ice for 30 days, circling the Pole twice. "It will give us a 30-day exposure to whatever neutrinos might be present," Gorham said.
The antennas will cover about half of the balloon's underside, he said, calling it "a funny telescope. Instead of looking up, it will be looking down."
The scientists will listen for "snaps" with a distinct characteristic, he said.
He said his project "will give us an early view of these potential neutrinos from high energy cosmic rays" but very precise measurements can't be made from one balloon.
The physicists want to drill into a salt dome and embed antennas to get a more exact picture of neutrinos at extremely high energies.
Peter Gorham, associate professor of physics
U.S. Department of Energy High Energy Physics Division
University of Hawaii
