Alpha particle

Alpha particles, also called alpha rays or alpha radiation, are tiny bits of matter made up of two protons and two neutrons bound together. They look just like the nucleus of a helium-4 atom. We call them alpha particles because they are named after the first letter of the Greek alphabet, which is α.

These particles are usually created when some radioactive materials go through a process called alpha decay, but they can also come from other processes. Because they are the same as helium nuclei, we can also write them as He²⁺ or ⁴₂He²⁺, which means a helium ion that is missing its two electrons. Once they pick up electrons from around them, they become normal helium atoms ⁴₂He.

Alpha particles are very good at pushing other atoms apart, which makes them very ionizing. But they do not go very far through things. Usually, just a few centimeters of air or the outer layer of skin can stop them. However, some special alpha particles called long-range alpha particles, which come from something called ternary fission, have three times more energy and can go three times farther. Also, some alpha particles from cosmic rays have a lot of energy and can go through the human body and even many meters of solid material, depending on how much energy they have.

Name

The name "alpha particle" was created by Ernest Rutherford when he studied uranium radiation. He noticed the radiation had two types: one he called "α radiation" and a more powerful type he called "β radiation." After more experiments, Rutherford and Hans Geiger found that alpha particles, once they lose their charge, become helium atoms. Alpha radiation is made of particles similar to helium atoms that have lost electrons. This is how we get helium gas on Earth.