"Alpha decay 2" M238 = 238.0507884 M234 = 234.0435998 M4 = 4.00260325413 E = (M238 - M234 - M4) 931.49410372 E Z = 90 tau12 = exp(3.682 Z / sqrt(E) - 120.8) "s" tau12 tau12 = tau12 / (365.25 24 60 60) "yr" / "s" tau12 Run