The mean path length of alpha-particles in air under standard conditions is defined by the formula R = 0.98.10-27 v3o cm, where vo (cm/s) is the initial velocity of an alpha-particle. Using this formula, find for an alpha-particle with initial kinetic energy 7.0 MeV:
(a) Its mean path length;
(b) The average number of ion pairs formed by the given alpha-particle over the whole path R as well as over its first half, assuming the ion pair formation energy to be equal to 34 eV.