Question

Why does positron decay occur?

Answer 1

Positron decay, or beta-plus decay, is a subtype of beta decay in which a proton inside a nucleus is converted to a neutron while releasing a positron and a neutrino.

A positron is the antiparticle of the electron, i.e. it has a +1 charge and the same mass as an electron.

Here's an image illustrating the difference between positron decay and beta-minus decay

Notice that nuclear transmutations take place in both cases, and that each type of beta decay brings the initial ratios of protons to neutrons in the nucleus to 1:1, this being the main reason for their occurrence.

Here's a link to a more detailed answer other contributors have posted:

http://socratic.org/questions/how-does-positron-emission-occur