We asked what particle the European Spallation Source (ESS) facility will use to image specimens viewed by the world's most powerful microscope.
The ESS facility will use a kilometer-long particle accelerator to generate neutrons that scientists will use to create extremely powerful imaging beams for a spallation matterscope.
Spallation refers to the process of jarring loose subatomic particles by firing other particles into a matter source. In the case of ESS, a series of protons will be fired at a metal plate and blast loose neutrons that can be collected for imaging. Spallation avoids nuclear fission's messy radioactive side effects, and doesn't present the threat of runaway chain reactions. Matterscope refers to the use of neutrons, rather than electromagnetic energy that electron or light-based microscopes use.
But why bother with neutrons when electrons are much easier to come by and are actually smaller? Neutrons are relatively nonreactive with the vast majority of molecular and atomic structures. Additionally, under certain conditions they behave both as particles and waves, which means that the spallation matterscope can avoid various forms of reactive interference and can produce images that are far more finely tuned than an electron microscope's.
While several neutron spallation matterscopes are already in operation, the proposed ESS facility's scale, precision, and use of multiple complementary imaging targets makes it stand out. If all goes according to plan, the ESS matterscope should be able to observe the division of individual atoms and provide unprecedented scientific insight into the mechanics of atomic physics and molecular chemistry.