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 ...

There Aldo Antognini's team generates so-called muonic helium-3, in which the two electrons of the helium atom are replaced by an elementary particle called a muon. This allows the nuclear radius to ...