BBC:
Although neutrons were discovered 79 years ago, some of their
basic properties have been difficult to measure precisely. One
trick to gain better precision is to create a large number of
ultracold, or very slow-moving, neutrons to study. With a
refined version of
an
approach they developed in 2007, Oliver Zimmer of the
Institut Laue Langevin (ILL) in Grenoble, France, and
colleagues used superfluid helium-4 at a frigid four degrees
above absolute zero to trap neutrons at a density of 55 per
cubic centimeter. That breaks the previous density record,
which was also set at the ILL. Zimmer believes the new approach
could bring the neutron density to 1000 per cubic centimeter,
which would serve to increase the statistical precision of
experiments and help exclude theories beyond the standard
model.
