By Brien Barnett Sun staff
An experiment at South Pole is offering a different view of neutrinos, the mysterious space particles that may hold information about the physical universe. Dave Besson, professor of physics at the University of Kansas, is developing the $400,000 Radio Ice Cherenkov Experiment at South Pole Station. RICE is a set of detectors designed to pick up radio waves given off by the collision of high-energy subatomic particles called neutrinos with the dense, clear ice below the station. “In principle a neutrino telescope is giving us a new way of looking at the universe. It’s a new map,” Besson said.
The kind of neutrinos sought by RICE and the $270 million IceCube project, also at South Pole, come from far outside our solar system and may help space physicists learn more about the formation of the universe. As complementary projects, IceCube uses optical detectors to gather visible light in the ice while RICE seeks radio waves. The collision of a neutrino with an ice molecule creates both visible light and radio waves.
The first RICE array was installed in the 1997-1998 season and monitored through 2000. It consisted of radio receivers and was intended to demonstrate the feasibility of the technique. However, without a known source of neutrinos, the project hasn’t found any of the specific neutrinos his team is seeking, Besson said. Co-deploying with IceCube will extend the array and make detecting one more likely, he said. “We realized that the first generation experiment was going to be a prototype experiment,” Besson said. “The second generation experiment should actually see neutrinos from active galactic nuclei, but if after this we didn’t see anything then that would present a problem with our model.” Besson said the RICE team has been a “nominal” participant in IceCube to this point, but is becoming more involved as the benefits of incorporating multiple technologies, including radio and acoustic detectors, seems to make more sense.
RICE and other experiments would serve two purposes in helping IceCube, Besson said. The first is to gather its own data, but then secondly to confirm any neutrinos detected in the system. If the visible light detectors see something, then the radio and acoustic detectors may as well. RICE isn’t the only project searching for neutrino-based radio waves, but Besson said it’s the first to incorporate the ice. “There was a group based at Berkeley that went to Antarctica and took (radio) measurements, but we were first to take data,” Besson said.
A long-duration balloon test project that was flown last season, Anita-lite, used the same concept as RICE. The key difference between the two was Anita-lite used the entire Antarctic ice sheet as its filter. No data has yet been released from the balloon project. NSF-funded research in this story: David Besson, University of Kansas.
