Gamow factor

Summary

The Gamow factor is the probability that two positively charged nuclei tunnel through their mutual electric repulsion. Only then do they come close enough to fuse. It is approximately $\exp(-\sqrt{E_G / E})$, where $E$ is the energy of the collision. The Gamow energy $E_G$ depends on the charges and the masses of the nuclei. It makes nuclear fusion possible in stars at temperatures far below those that classical physics would require. Combined with the Maxwell–Boltzmann distribution of energies, it shows that most reactions happen in a narrow window of energies, the Gamow peak.