IBHL+NUCLEAR+PHYSICS

IB PHYSICS > QUANTUM AND NUCLEAR PHYSICS
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NUCLEAR PHYSICS
Explain how the radii of nuclei may be estimated from charged particle scattering experiments.

Kinetic energy is converted into potential energy at the position of closest approach ke = pe ke = kQq/r

EXAMPLE: Alpha particle with energy 4.2 MeV approaches gold nucleus (Z=79). Find distance of closest approach. ANS: 5.4 x 10 -14 m

Use of energy conservation for determining closest-approach distances for Coulomb scattering experiments is sufficient.

Describe how the masses of nuclei may be determined using a Bainbridge mass spectrometer.



Students should be able to draw a schematic diagram of the Bainbridge mass spectrometer, but the experimental details are not required Students should appreciate that nuclear mass values provide evidence for the existence of isotopes. mv 2 /r = Bqv

Describe one piece of evidence for the existence of nuclear energy levels.



For example, alpha (α) particles produced by the decay of a nucleus have discrete energies; gamma‑ray (γ-ray) spectra are discrete. Students should appreciate that the nucleus, like the atom, is a quantum system and, as such, has discrete energy levels.