Helium is the simplest element in the periodic table with more than one particle in its nucleus, yet state of the art theory and experiments on it don't add up.

An atom consists of a heavy center, called the nucleus, made of particles called protons and neutrons. An atom has lighter ...

An international research team led by the Paul Scherrer Institute PSI has measured the radius of the nucleus of muonic helium-3 with unprecedented precision. The results are an important stress ...

Atoms make up everything and are incredibly small. They are formed of a nucleus, protons, and electrons.

"Our experiments with muonic helium-3 provide the most accurate value to date for the charge radius of this nucleus," says Randolf Pohl, who is also a member of the PRISMA + Cluster of Excellence ...

Protons are tiny particles just a femtometer across, but without them, atoms wouldn't exist. Protons are tiny subatomic particles that, along with neutrons, form the nucleus of an atom. The ...

For example, a helium atom has an atomic mass of 4, but an atomic number (or positive charge) of 2. Since electrons have almost no mass, it seemed that something besides the protons in the nucleus ...

The question of where atoms come from requires a lot of physics to be answered completely – and even then, physicists only have good guesses to explain how some atoms are formed.

Many heavy atoms form from a supernova explosion, the remnants of which are shown in this image. NASA/ESA/Hubble Heritage ...

Almost everything on Earth is made up of atoms, but where do these fundamental building blocks come from?