One of the most valuable assets owned by Lancaster University is stored in beer kegs.<\/p>\n
But it’s not in one of the student bars.<\/p>\n
In a carefully locked laboratory rows of metal kegs are arranged on shelves and linked together with spindly copper pipework.<\/p>\n
The containers aren’t loaded with prize beer but rather a gas called helium-3, one of the most expensive materials in the world. A single litre costs roughly $2,000 (\u00a31,500), though the price can fluctuate.<\/p>\n
“The lab has been going for 50 years or so. Back then, the helium was quite cheap,” says Dima Zmeev, senior lecturer. “Our very wise predecessors stocked up.”<\/p>\n
In the near future, more people could be looking to build up such a stockpile. Helium-3 has applications in quantum computing and nuclear fusion. However, the main source of it today is tightly controlled \u2013 it comes from nuclear weapons. Specifically, from the decay of tritium, a form of hydrogen, inside those weapons.<\/p>\n
Around the world, tens of thousands of litres of helium-3 are likely to be produced this way every year, estimates David McCollum, distinguished scientist at Oak Ridge National Laboratory in Tennessee. But future demand could far exceed that supply.<\/p>\n
Some entrepreneurs and researchers say we need new sources of helium-3. It exists in the ground, though generally at very low concentrations.<\/p>\n
However, samples of moon dust, or regolith, from the Apollo missions suggest it may be present there at relatively high concentrations. As such, plans are now afoot to recover helium-3 from the moon.<\/p>\n
Helium-3 is an isotope of helium, defined by the number of neutrons in the atom’s nucleus. Helium-4, with one additional neutron, is the comparatively cheap version \u2013 a gas that fills children’s party balloons.<\/p>\n
Zmeev uses helium-3 in physics experiments. For example, he fills tiny chambers with the stuff, in a project to detect a type of mysterious dark matter particle.<\/p>\n
Should such a particle knock into one of the helium-3 atoms, it would make them all jiggle. This generates heat and that slight temperature rise can be measured.<\/p>\n
The helium-3 can be re-used again and again.<\/p>\n
Scientists mix helium-3 and helium-4 together at very low temperatures to create the lowest temperatures in the known universe, down to the millikelvin range (-273C).<\/p>\n
When helium-3 atoms gradually separate from a dilute mixture containing the two isotopes, they form a pure helium-3 layer on top. This separation is a phase change that consumes energy, inducing a cooling effect<\/a>, like when steam evaporates off a cup of hot water.<\/p>\n Helium-3-based cooling, or dilution refrigeration, is crucial for quantum computers.<\/p>\n