73. (a) Following Sample Problem 43-10, we compute Å» h (4.14 × 10-15 eV·fs)/2Ä„ "E H" = =6.6 × 106 eV . tavg 1.0 × 10-22 s (b) In order to fully distribute the energy in a fairly large nucleus, and create a compound nucleus equilibrium configuration, about 10-15 s is typically required. A reaction state that exists no more than about 10-22 s does not qualify as a compound nucleus.