Helium, helium shortage | Homeland Security Newswire

Helium shortageWorking around helium shortage

Published 13 June 2018

Doctors use X-rays to see inside people, and scientists use neutrons to peer inside advanced materials and devices such as fuel cells to better understand and improve them. But a critical shortage of a rare form of helium used for detecting neutrons—which are difficult to spot directly—threatens to slow advances in this critical type of materials research. Scientists found a way to replace expensive and scarce helium-3 gas with previously studied crystals of more abundant materials.

Doctors use X-rays to see inside people, and scientists use neutrons to peer inside advanced materials and devices such as fuel cells to better understand and improve them. But a critical shortage of a rare form of helium used for detecting neutrons—which are difficult to spot directly—threatens to slow advances in this critical type of materials research.

NIST says that that to solve the problem, a NIST team found a way to replace expensive and scarce helium-3 gas with previously studied crystals of more abundant materials. Their improved approach achieved greater than 90 percent efficiency in detecting neutrons, making it a viable alternative.

Helium-3 is a rare isotope of helium with one neutron instead of two. Its nucleus breaks apart easily when struck by a neutron, and the fragments can be detected when they strike a high-voltage wire. For decades, this has made helium-3 an ideal tool for materials scientists, who use neutrons to probe the innards of dense objects. National security officials also use it in ports and at border crossings to spot the stray neutrons emanating from illicit radioactive materials such as the ingredients for nuclear bombs.

Ironically, it is the manufacture of nuclear weapons that provided a steady supply of helium-3 in the first place. The isotope is hard to come by; it only makes up about 0.0001 percent of Earth’s natural helium reserves. But it is one of the decay products of tritium, a key element in hydrogen bombs, and scientists have siphoned off the helium-3 from idle warheads for decades. Now that the United States has reduced its production of such explosives, materials scientists need a new way to detect the neutrons they beam at cutting-edge materials, which scatter the neutrons in ways that reveal their internal structure.

Scientists have long known of another detection method that uses the more available chemicals zinc sulfide and lithium-6 fluoride, but its utility has been limited for exploring dense materials because of its inefficiency. Scientists need the most efficient detection method they can find, since even the most intense neutron sources only produce low-intensity trickles of neutrons.

“Helium-3 is the gold standard for neutron detection work because its efficiency is around