Very large nuclei may spontaneously emit an alpha particle . The alpha particle
is a 
He nucleus consisting of two protons and two
neutrons. This type of radioactivity is not
normally produced at TRIUMF by the
operation of the cyclotron . However there are sources on site
used mainly for calibration of instruments which do emit this type of radiation.
Figure:2.3 The alpha decay of
Am
An example is the decay of
Am to form
Np
(Fig. 2.3
):
