Radioactive nuclei, radioactive radiation

Many atomic nuclei emit particles without any external effect and transform themselves into other nuclei.
These nuclei are radioactive, and the process is called radioactive decay. The emitted particles form the radioactive radiation.
Types of radioactive decay:

There are three types of decay of natural radioactive materials: alpha (), beta () and gamma () decay. These differ from each other by the emitted particles.

Alpha particles are positively charged, beta particles are negatively charged, whereas gamma photons are neutral. Therefore a mixed radiation can be separated into three components using electrical fields.