An α-particle will have a discrete energy, characteristic of the emitting nucleide, whence α-spectra
have sharp peaks.
Negatron Decay
This is a process characteristic of nucleides with high n:p ratios, and involving the loss of an electron
from the nucleus, which is usually, but not invariably accompanied by the emission of γ-photons. A
detailed energy balance reveals that the simple picture cannot account for all the energy lost by the
nucleus in the decay and the emission of an additional particle – the antineutrino, is postulated to
account for this. The general equation for a negatron emission is
which implies the decay of a neutron into a proton and an electron (negatron) which is expelled.
The exact energy carried by an emitted negatron will depend upon the angle between its path and that of
the antineutrino. As the angle can vary from atom to atom, so will the distribution of energy between
the particles. Negatron spectra (Figure 10.3) thus do not have sharp peaks.
Figure 10.3
Energy spectrum of^32 P negatrons.A low n:p ratio in a nucleus gives a situation which may be stabilized by the conversion of a proton into
a neutron. One process which may effect this is positron emission,
The positron has a short life and will quickly be annihilated in a reaction with an electron, producing γ-
photons of characteristic energy (0.51 MeV). In addition, the basic nuclear process itself is usually
accompanied by the emission of γ-radiation. As in the case of negatron decay a complete energy