Collision Theory

                                                                        (A)

Rearranging

                                                                        (B)

Solving for r*

                                                                                 (C)

Recalling Eqn. (43)

                                                                                  (43)

Substituting Eqn. (C) for r* in Eqn. (43)

                                                                  (E)

Rearranging

                                                       (F)

                                              (G)

Finally, collecting terms we have

                                                          (H)

Note: S₁ is positive, S₂ is negative, and r₂ > r₁; therefore  is positive as is g_P.