Absorption of Nuclear Radiation 131 FIG. 6.5. Cloud chamber tracks of or,/~, (e') and V-rays at I bar in air ((a), (b), and (c)) and in methane (d). (From W. Gentner, H. Maier-Leibnitz, and H. Bothe.) ~z = 0.173 Et~ 3/2 Az 1/3 (mg cm -2) (6.11)