  We investigate heteronuclear collisions in isotope mixtures of laser-cooled
metastable 3P2 neon. Experiments are performed with spin-polarized atoms in a
magnetic trap for all two-isotope combinations of the stable neon isotopes
20Ne, 21Ne, and 22Ne. We determine the rate coefficients for heteronuclear
ionizing collisions to beta_{21,20}=(3.9+/-2.7) x 10^{-11} cm^3/s,
beta_{22,20}=(2.6+/-0.7) x 10^{-11} cm^3/s, and beta_{21,22}=(3.9+/-1.9) x
10^{-11} cm^3/s. We also study heteronuclear elastic collision processes and
give upper bounds for heteronuclear thermal relaxation cross sections. This
work significantly extends the limited available experimental data on
heteronuclear ionizing collisions for laser-cooled atoms involving one or more
rare gas atoms in a metastable state.
