The word, positron, sounds like it might have come from Star Trek or some other science fiction series or movie. However, positrons are real particles. To understand what they are, it is helpful to understand some of the properties of the particles of an atom.
Atoms are tiny objects that are made up of even tinier ones, each with specific properties. The nucleus or center of the atom is made up of up to two kinds of particles; protons and neutrons.
Protons have a positive electrical charge. As sub-atomic particles go, protons are fairly large. A proton accounts for a major portion of the mass of an atom, and heavier elements contain more protons within the nucleus of the atoms of that element.
Neutrons are roughly the same mass as protons, however they have no electrical charge. A neutron basically adds to the mass of the atom without changing the net charge of the atom.
The third sub-atomic particle is the electron. An electron has a negative charge and orbits around the nucleus of the atom. At one time, it was believed that electrons orbited much as planets do around a star. In the last few decades, though, this has been called into question. Still, the negative charge of an electron balances the positive charge of the proton.
For example, hydrogen contains one proton and one electron, so the atom has a net charge of 0. Not all atoms are perfectly balanced, and this is also true of some forms of hydrogen, called hydrogen isotopes.
An interesting feature of electrons is that they are incredibly small, even in terms of an atom. Though the charge balances that of the relatively large proton, the mass of an electron is almost 2000 times smaller. As will be seen, this is important in defining what a positron is.
With a basic understanding of the ‘normal’ sub-atomic particles, positrons can start being defined.
Positrons were postulated long before they were actually found. A positron is the mass of an electron, however instead of having a negative charge, it has a positive charge. So far, this may not seem all that strange. This is where the Star Trek sort of science fact comes in.
Combining a positron and an electron results in the total destruction of both. That isn’t quite stated correctly. Both particles are converted to energy. According to Einstein and Newton, matter and energy are simply different forms of the same thing, but can neither be destroyed nor created.
This is a long-winded way of saying that a positron is the anti-matter equivalent of an electron. This isn’t strictly hypothetical. Positrons have been observed under scientific conditions.
While this is a basic answer to what a positron is, these particles are the positively charged counterpart of electrons, and as such, they are the anti-matter equivalent as well. Study continues, however, it isn’t easy since positrons react so violently when they come in contact with electrons, which are present in the matter we know and are acquainted with.
Special acknowledgement to Lewis Ansell, professor of physics, dec.