Earlier this week a group of scientists at the Fermi National Accelerator Laboratory (Fermilab) in Illinois began an experiment in which they send a continuous beam of neutrinos to a large iron detector deep in an underground mine in Soudan, Minn. The neutrinos are traveling through parts of Wisconsin, including Madison.

“They [will] go underneath Madison, sort of underneath the interstate on the east side,” University of Wisconsin Physics Professor Albert Erwin said.

Neutrinos are uncharged elementary particles that rarely interact with other particles and may or may not lack mass.

“Neutrinos have been very mysterious,” Erwin said. “We have believed for many years that they have no mass.”

Matter decaying radioactively will give off the harmless neutrinos as they pass through the soil beneath Wisconsin residents over the course of the next few weeks.

“So far the beam has been working as designed,” University of Minnesota-Twin Cities physics professor Ken Heller said.

The University of Minnesota is home to many of the scientists working on this experiment with Erwin as the only representative from UW.

The “far detector” in Soudan has been operating for more than a year, according to Heller, and thus far scientists have seen only cosmic ray events there. Heller added he expects the Soudan laboratory to begin detecting the neutrino beam sometime near the end of March.

“It depends a little bit on the details of bringing up the beam,” Heller said. “We want to be careful in bringing the neutrino beam up — it’s a very high-intensity beam.”

Erwin said he hopes the experiment will continue to provide evidence for the supposed mass of neutrinos, opening the door to exciting possibilities concerning the makeup of the universe.

“As they travel, they change their ‘flavor,’ like a fox changing into a coyote or something” Erwin said, adding the only theoretical way neutrinos can change their nature is to have mass.

According to Erwin, there is a huge amount of missing matter in the universe not accounted for in visible matter and the discovery of neutrino mass could impact this theory.

“We look out and we see galaxies and planets and we know what the sum total is, and the stuff we see is just 5 percent of [that] total,” he said.

Erwin credits scientists in Japan for paving the way for American scientists in the field of neutrino science.

“The Japanese have been tracking down this thing with cosmic rays from outer space that hit the upper atmosphere and [then] make neutrinos up there,” Erwin said. “They have been comparing the neutrinos that have come from the other side of the world with the ones that have come from this side. They’re the pioneers.”

Experiments in Japan have been concentrated on neutrinos in the atmosphere derived from the sun, the first place neutrinos were noticed.

“The Japanese are pretty excited about it,” Erwin said. “It’s the first time they’ve been the leaders in something this exciting.”

Expressing his enthusiasm over the upcoming experiment, Erwin stressed, “this changes everything we’ve been thinking for the last 50 years.”