Subatomic Physics

10.12. References 327
(b) Compare the transition rates for emission and absorption. Compare the
ratio with the ratio expected from time-reversal invariance.
10.11. Prove Eqs. (10.71) and (10.72).
10.12. Sketch the radiation pattern predicted by Eqs. (10.75) and (10.76) for dipole
radiation, assuming that the vector 〈β|x|α〉 points along the z direction. Compare
to the radiation pattern for classical dipole radiation.
10.13. Use Eq. (10.77) to make a crude estimate for the mean life of an electric dipole
transition
(a) In an atom, Eγ =10eV.
(b) In a nucleus, Eγ =1MeV.
Find relevant transitions in nuclei and atoms and compare your result with
the actual values.
10.14. Discuss an accurate method for determining the fine structure constant.
10.15. Why do nuclei and particles not have permanent electric dipole moments?
Why can some molecules have permanent electric dipole moments?
10.16. Why does the transition Σ 0 → Λ 0 occur through an electromagnetic and not
a hadronic decay?
10.17. What kind of multipole transition is involved in the decay Σ 0 → Λ 0 ? Use
an extrapolation of Fig. 10.10 to estimate the mean life. Compare to the
presently known value.
10.18. Discuss time-to-amplitude converters (TACs).
(a) Describe the function of a TAC.
(b) How can a TAC be used to measure lifetimes?
(c) Sketch the block diagram of a TAC.
10.19. Show that a 2 + γ → 0 + transition, as, for example, shown in Fig. 10.7, cannot
occur through dipole radiation.
10.20. Verify that the selection rules of Eq. (10.80) and the conservation laws of
Eq. (10.81) together lead to the multipole assignments shown in Fig. 10.9.
10.21. The transition from an excited to a nuclear ground state can usually proceed
by two competing processes, photon emission and emission of conversion
electrons.