I.

Introduction

Beta Particle, electrically charged particle emitted by certain radioactive elements, such as uranium and berkelium. Beta particles are produced when the nucleus of an unstable atom spontaneously decays, or transforms, changing the atom into an atom of a more stable element. In this process, the nucleus emits a beta particle and another elementary particle called a neutrino. Two types of beta decay occur. One type releases a positively charged beta particle called a positron; the other type releases a negatively charged beta particle called a negatron. The negatron is identical to the electron found in atoms.

The terms beta particle and beta radiation are used interchangeably. The term beta ray originally referred to a stream of beta particles, but it is no longer used. See also Radioactivity.