When there was no ionising radiation present
Wilson found that the clouds showed a uniform distribution
of droplets.
When
the chamber was ionised with alpha-particles clear,
straight tracks were emitted from the radium source.
Wilson said his photographs gave 'a poor idea of the
really beautiful appearance of these clouds'..
Beta-particles
produced 'two or three absolutely straight thread-like
lines' from the direction of an impure radium salt source.
The tracks produced by beta-particles were less clear
than those produced by alpha-particles. Less energetic particles
would spiral in the earth's field.
We
now know that beta-particles are electrons and alpha-particles
are atomic nuclei of the element helium. Beta-particles
are negatively charged while alpha-particles have a
positive charge of twice the magnitude. Alpha-particles
are more ionising than beta-particles.
