Rare-Gas Collision Broadening in the LowestP13Level of Cd

Alignment depolarization collision cross sections have been measured for the lowest ${}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ level of cadmium broadened by the rare gases. Cross sections obtained with the Hanle effect (zero-field level crossing) and the method of modulated-light double resonance are the same within approximately 5%. They agree with theoretical predictions except in the case of helium, for which the measured cross section is nearly twice as large as the theoretical value. Average experimental values (units of ${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$) for He, Ne, Ar, Kr, and Xe, respectively, are 51, 52, 81, 118, and 165.