Fixed-Target Experiments
In a fixed-target experiment, a beam of high-energy particles is aimed
at a target fixed in place in the laboratory.
A charged particle such as e+, e-, p, or anti-p,
is accelerated by an electric field and collides with a target,
which can be a solid, liquid, or gas. A detector determines charge,
momentum, mass, etc. of the resulting particles.
In 1909 Geiger
and Marsden used a fixed target of foil to scatter particles
from a radioactive source. The deflection of a few particles at
large angles led Rutherford in 1911 to the hypothesis of a small,
dense nucleus.
What did people believe the atom was like before Rutherford?
