You may not know much about helium, except that it fills birthday balloons and blimps and can make even the most stentorian voice sound a bit like Donald Duck.

But helium is an important gas for science and medicine. Among other things, in liquid form (a few degrees above absolute zero) it is used to keep superconducting electromagnets cold in equipment like M.R.I. machines and the Large Hadron Collider at CERN, the European Organization for Nuclear Research, which uses 265,000 pounds of it to help keep particles in line as they zip around.

Helium’s role in superconductivity and other applications has grown so much that there have been occasional shortages. The gas forms in nature through radioactive decay of uranium and thorium, but exceedingly slowly; in practical terms, all the helium we will ever have already exists. And because it does not react with anything and is light, it can easily escape to the atmosphere.

Until now, it has been discovered only as a byproduct of oil and gas exploration, as the natural gas in some reservoirs contains a small but commercially valuable proportion of helium. (The first detection of helium in a gas field occurred in the early 1900s when scientists analyzed natural gas from a well in Dexter, Kan., that had a peculiar property: It would not burn.)

But now scientists have figured out a way to explore specifically for helium. Using their techniques, they say, they have found a significant reserve of the gas in Tanzania that could help ease concerns about supplies.

"We’re essentially replicating the strategy for exploring for oil and gas for helium,” said Jonathan Gluyas, a professor of geoenergy at the Durham University in England. One of his graduate students, Diveena Danabalan, presented research on the subject on Tuesday in Yokohama, Japan, at the Goldschmidt Conference, a gathering of geochemists.

One key to developing the technique, Dr. Gluyas said, is understanding how helium is released from the rock in which it forms. Ordinarily, a helium atom stays within the rock’s crystal lattice. "You need a heating event to kick it out,” he said. Volcanoes or other regions of magma in the earth can be enough to release the gas, he said.

Once released, the helium has to be trapped by underground formations — generally the same kind of formations that can trap natural gas, and that can be found using the same kind of seismic studies that are undertaken for oil and gas exploration. The helium, which is mixed with other gases, can be recovered the same way natural gas is: by drilling a well.

Working with scientists from the University of Oxford and a small Norwegian start-up company called Helium One, the researchers prospected in a part of Tanzania where studies from the 1960s suggested helium might be seeping from the ground. The area is within the East African Rift, a region where one of Earth’s tectonic plates is splitting. The rifting has created many volcanoes.

Dr Gluyas said the gas discovered in Tanzania may be as much as 10 percent helium, a huge proportion compared with most other sources. The researchers say the reservoir might contain as much as 54 billion cubic feet of the gas, or more than twice the amount currently in the Federal Helium Reserve, near Amarillo, Tex., which supplies about 40 percent of the helium used in the United States and is being drawn down.

The next step would be for Helium One or one of the major helium suppliers around the world to exploit the find. But for Dr. Gluyas, the research opens up the possibility of finding the gas in new places.

"We’re in the position where we could map the whole world and say these are the sorts of areas where you’d find high helium,” he said.