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In reading about radioactive decay, if these equations are right,

Beta decay: Neutron =>proton + electron + neutrino

Positron emission: Proton => positron + neutron + neutrino

A product of the decay of a neutron (the proton) can, during positron emission, decay to form a neutron. How can a proton decay to form a neutron in positron emission if, as indicated by beta decay, it is a part of a neutron?


A proton is not part of a neutron. A neutron is not part of a proton. They are very similar particles. According to quantum theory, each is made of three particles called quarks. One of these three quarks is different for protons as compared to neutrons. A neutron has just a little bit more mass than a proton.

Given enough energy, each can change into the other. To maintain the balance of the universe, the other particles must be emitted during the change. The electron or positron maintains the balance of electric charge. An anti-neutrino is emitted with the electron. A neutrino is emitted with the positron (i.e. anti-electron). This maintains the balance of leptons. Without such balances, the universe could easily get out of control.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College

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