Inside an atomic nucleus, the two main constituents are protons and neutrons, collectively known as nucleons. However, there are other particles that can be present, although they are less common. These particles are called exotic particles or nuclear isomers. Here are a few examples:
Mesons: Mesons are particles composed of a quark and an antiquark. They can be found inside atomic nuclei in some cases. The most common mesons found in nuclei are pions (π+ and π-). They play a role in the strong nuclear force that binds protons and neutrons together.
Hyperons: Hyperons are particles made up of three quarks, including strange quarks. Hyperons can be present in certain types of atomic nuclei, although they are relatively unstable and decay quickly.
Delta particles: Delta particles are baryons, similar to protons and neutrons, but they have a higher mass. They consist of three quarks and can be found inside atomic nuclei. Deltas are involved in the strong nuclear force and contribute to nuclear stability.
Nuclear isomers: Nuclear isomers are excited states of atomic nuclei that have a longer lifetime than typical excited nuclear states. They are formed when the nucleus is in an excited energy state, often after absorbing a photon or undergoing a nuclear reaction. These isomers can have different spins and parities compared to the ground state of the nucleus.
It's important to note that while these particles can be present inside atomic nuclei, protons and neutrons are the most abundant and stable components, forming the backbone of the nucleus. The other particles mentioned above are less common and often exist in specific, less-stable configurations.