Undergraduate Course Handbook - University of Oxford Department ...

B2: III. Quantum, Atomic and Molecular Physics, and IV. Sub-Atomic PhysicsEach section is 1.5 hour in duration and has four questions.Answer two questions in each section offered.III. Quantum, atomic and molecular physicsEinstein A&B coefficients. Semi-classical treatment of two-levelsystem: rate equation limit, Rabi oscillations and Bloch sphere.Decaying states and Lorentzian lineshape.Classical uncertainty in quantum mechanics: pure and impurestates. The density matrix and trace rule. Time-evolution of thedensity matrix. Measurement and loss of coherence.Multi-electron atoms and the central field approximation. Electronconfigurations, shell structure and the Periodic Table. Atomswith 1 or 2 valence electrons. Residual electrostatic interaction,singlet and triplet terms, LS-coupling. Spin-orbit interaction (finestructure).Simple ideas of atomic spectra and energy levels, spectroscopicnotation. Selection rules for electric dipole radiation. X-rays.Magnetic dipole hyperfine structure; weak and strong magneticfield phenomena in both fine and hyperfine structure;.Basic ideas of molecular physics, Born-Oppenheimer approximation,vibrational and rotational motion. Molecular spectra,Franck-Condon principle. [Non-examinable: Simple ideas ofmolecular bonding, effects of exchange symmetry in homonucleardiatomic molecules.]Homogeneous and inhomogeneous broadening of spectral lines.Saturated absorption and saturated gain. Minimum conditionsfor laser operation, population inversion, the optical gain crosssection,rate equations governing population inversion and growthof laser radiation; cavity effects. 3- and 4-level laser systems.Frequency tuning of lasers.IV. Sub-atomic PhysicsKnowledge of the special relativity in the Prelims paper CP1will be assumedConcept of a scattering cross section, Quantum mechanicalscattering; The Born approximation. Feynman rules in quantummechanics. Yukawa potential, propagator, virtual particleexchange. Resonance scattering, Breit-Wigner; decay widths.Fermi’s golden rule. Use of invariants in relativistic particledecay and formation.Elastic and inelastic scattering; form factors. Structure of thenucleus: nuclear mass & binding energies; stability, radioactivity, and decay; measurement of radioactivity with semiconductordetectors; Fermi theory, the (A,Z) plane.Energy production through fission (nuclear reactors), fusion (p-pand D-T) in the Sun and Tokamaks. The p-p & CNO cycles.Solar neutrinos. Stellar structure; formation of heavier elements.Quark model of hadrons: the light meson and baryon multiplets;nucleons as bound states of quarks; quarkonium; the ratio ofcross-sections (e+ + e- to hadrons) to (e + + e- to muons); phenomenologyof deep inelastic scattering.The Standard Model: quark and lepton families, fundamentalinteractions and flavour mixing. The strong interaction andqualitative discussion of confinement. Weak interaction; decayof the neutron and parity violation. Production, experimentaldetection, and decay of the W and Z bosons; the width of the Zand the number of neutrino types; neutrino oscillation.43