For a radium alpha decay, Z = 88, z = 2 and m = 4 m p, E G is approximately 50 GeV. Gamow calculated the slope of log ⁡ ⁡ ( λ λ ) with respect to E at an energy of 5 MeV to be ~ 10 J, compared to the experimental value of 0.7 × 10 J.