European researchers working at the Institut Laue-Langevin (ILL) in Grenoble, France, have trapped the largest number of neutrons ever held in place at one time. But while they’ve smashed the previous record (also held by the ILL), it’s still not quite enough, the lead researcher tells BBC. Still, the new approach that got researchers this far may be able to trap far greater numbers of neutrons with a little finessing.
Neutrons may seem like the boring cousin to the more active and interesting protons and electrons that make up atoms, but neutrons hold some mysteries that could shed light on the Big Bang and the formation of the cosmos (life, the universe, everything, etc.). They can also mysteriously become other subatomic particles, like protons, electrons, and electron antineutrinos–a pretty neat trick of physics. But it’s precisely because they have no electric charge that they are notoriously difficult to manipulate.
And because they are difficult to trap and manipulate, they are also very difficult to study. Knowing how they pull off this transformation to other subatomic particles would tell physicists quite a bit about neutrons, their role in the Big Bang and the Standard Model, and how the universe came to be.
But experiments thus far have lacked the kind of precision necessary to make accurate assessments, chiefly because when measuring neutrons physicists are trying to hit a moving target. But no more. At the ILL–the single highest-intensity neutron source on the planet–researchers have corralled neutrons at a density of 55 particles per cubic centimeter, a full five times more than they were previously able to bottle up.
They did so by using superfluid helium-4 to chill the neutrons down to -450 degrees–roughly nine degrees above absolute zero. At that temperature everything slows down, bringing even elusive subatomic particles like neutrons under enough control to hit the 55-per-cubic-centimeter mark.
Still, that’s not enough to get the kind of statistical precision researchers need to do the kind of science the researchers want to carry out. To answer the really big questions about the universe, they need even higher densities and higher sample sizes. But with some fine tuning they might be able to reach 1,000 neutrons per cubic centimeter, the lead researcher told BBC.