The transformation of the nuclei and the electron orbitals may result in electron emission. As discussed in Section 4.4.2, the negative or positive particles (namely, electrons or positrons following the transformation of the nuclei) are called nega­tive or positive beta radiation, respectively, and they have continuous spectra. The transformation of the atomic orbital can also produce electrons, as discussed in Section 4.4.3. These electrons, such as Auger and conversion electrons, have dis­crete energy. In addition, electromagnetic radiation can produce photo, Compton, and pair electrons, as discussed in Section 5.4.

The rest mass of the beta particle is 0.51 MeV, which is much less than the rest mass of the alpha particle. Therefore, at the same energy of the radiation, the veloc­ity of the beta particle is much higher than that of the alpha particle. Because of the high velocity, the relative increase in the mass often has to be taken into account.

When beta radiation interacts with matter, the electrons in the matter may get excited or ionized, and the direction of the pathway of the beta particle may change as a result of elastic and inelastic collisions. In addition, the kinetic energy is partly or totally transmitted to the matter. When the beta particles interact with the nuclear field, Bremsstrahlung is emitted, which has a continuous spectrum. The inner Bremsstrahlung has been discussed in Section 4.4.3.

The beta particles can be scattered and absorbed, eventually losing all their energy (Table 5.4).