- C Assume That At Energies Above 0 78 Mev Protons And Neutrons Are In Equilibrium With A Ratio Given By The Saha Equat 1 (101.19 KiB) Viewed 72 times
(c) Assume that at energies above 0.78 MeV protons and neutrons are in equilibrium, with a ratio given by the Saha equation: 3/2 Nn (mn N₂ - (₂) "* exp(- (mn - mp) c²) = Np mp. kot ²3 ) c²) KBT where: (mn - mp)c² = 1.29 MeV What is the ratio of neutrons to protons when the equilibrium first fails to hold? [4 marks] (d) Noting that a free neutron has a half-life of 10.3 minutes, calculate what the n:p number ratio is when the Universe has cooled to an energy of 0.061 MeV. [4 marks] (e) Assuming that all nucleosynthesis leading to He occurs around 0.061 MeV, estimate the H:He number ratio at this time under the assumption that the only stable neutrons will be bound in nuclei. [5 marks]