Principle
The relationship between the angle of scattering and the rate of
scattering of alpha-particles by gold foil is examined with a
semiconductor detector. This detector has a detection probability
of 1 for alpha-particles and virtually no zero effect, so that the
number of pulses agrees exactly with the number of alpha-particles
striking the detector. In order to obtain maximum possible counting
rates, a measurement geometry is used which dates back to Chadwick.
It is also possible in this case to shift the foil and source in an
axial direction (thus deviating from Chadwick's original
apparatus), so that the angle of scattering can be varied over a
wide range. In addition to the annular diaphragm with gold foil, a
second diaphragm with aluminium foil is provided in order to study
the influence of the scattering material on the scattering
rate.
Tasks
- The particle rates are measured at different angles of
scattering between about 20° and 90°. The measurements are compared
with the particle rates calculated by means of the Rutherford
theory for the measurement geometry used.
- The particle rates are measured in the case of scattering by
aluminium and gold with identical angles of scattering in each
case. The ratio of the two particle rates is compared with the
particle rate calculated from Rutherford's scattering
equation.
What you can learn about
- Scattering
- Angle of scattering
- Impact parameter
- Central force
- Coulomb field
- Coulomb forces
- Rutherford atomic model
- Identity of atomic number and charge on the nucleus
Software included. Computer not provided.