UH ocean project involves nuclear subatomic particles


POSTED: Monday, August 24, 2009

The University of Hawaii physics department is taking the lead in development of a deep-ocean detector to study ghostly subatomic particles coming from nuclear reactors and radioactive decay in the earth.

Neutrinos and their antimatter counterparts, anti-neutrinos, are particles that have so little mass that they routinely pass through the entire planet without hitting anything. But when they do collide with other matter, they provide a tiny light show that can be tracked by sensitive instruments.

This has both academic and real-world applications.

A nonintrusive neutrino detector could be placed next to a reactor and monitor it for the International Atomic Energy Agency, said UH physicist John Learned, co-spokesman for the Hanohano Project with Bill Mcdonough, University of Maryland geologist.

Uncooperative countries could be monitored from more than 600 miles away, Learned said.

“;Had we a big enough detector offshore, we could have seen the North Korean bomb test,”; he said.

Learned said there is broad interest in the Hawaii Anti-Neutrino Observatory among government agencies and scientists.

“;It's a few hundred million dollars project—serious money,”; he said.

Some funds are available for studies, “;but we haven't tapped into big money yet,”; Learned said. “;I hope we will have a strong role in technology (at UH). We would assemble and test everything.”;

Hanohano is being planned as a portable detector on a barge in 10,000 tons of scintillator oil so when neutrinos pass through and interact with particles, they give off flashes of light detected by photomultiplier tubes, Learned explained.

He said scientists are interested in studying geo-neutrinos in the mantle and crust to help learn the source of the earth's heat. The radioactivity is believed to supply most of the planet's internal heat, driving plate tectonics, sea floor spreading and volcanic activity, he said.

Government agencies are interested in monitoring nuclear reactors, which are likely to proliferate as oil runs out, Learned said. “;Inspectors largely have to depend on what folks are telling them about the reactor atomic materials, and it's very easy to cheat,”; he said. “;There's more pressure on the IAEA to keep track of reactors, and neutrinos are a fantastic way to do this because there is absolutely nothing you can do to shield neutrinos or fake them.

“;You not only can tell the reactor is on, but you can tell what is cooking.”;

The KamLAND experiment in Japan, in which Learned and other UH physicists participated, produced the first observations of neutrinos from the earth. Hanohano's detector concept is similar to KamLAND but will be 10,000 tons compared with KamLAND's 500 tons, Learned said.

Makai Ocean Engineering did some preliminary feasibility and design work for Hanohano with funding from the National Defense Center of Excellence for Research in Ocean.

“;It is a very significant challenge,”; said Joseph Van Ryzin, co-founder of the engineering company and senior engineer.

The detector would be transported on a barge and deployed to the ocean floor and retrieved, he said.

“;We've got to carry something that is much bigger than a nuclear submarine, drop it to the bottom, going much deeper than a nuclear sub, and turn around and bring it back to the surface and take it somewhere else.”;

Hanohano will have baby oil on the outside and dishwasher liquid soap inside, which is “;a good chemical for giving off this light when a neutrino hits it,”; Van Ryzin said. “;It would be 10,000 tons of scintillating fluid and all the stuff around it.”;

“;From an engineering point of view, it turned out to be really interesting,”; he said. “;We kind of worked out that you could take advantage of the unique characteristics of this detector and lower it to the bottom, and you could recover it and that was feasible.

“;The difficulty is cost. It's in a category where most high-energy physics experiments end up: costing lots of money.”;