Helium atom precision measurements and calculations have a history of nearly a century. In the 1960s, theorists discovered that the fine-structure split (23P0-23P2) of the 23P energy level of helium ...

For the first time, researchers from the PRISMA + Cluster of Excellence have determined the charge radius of helium-3 and thus also the exact difference to the radius of helium-4. This precision ...

The interest in exotic atoms arises from the fact that they often facilitate the most basic experimental strategy used in physics: changing a single parameter or component in an otherwise complex ...