We use classical molecular dynamics simulations to investigate temperature control of unsupported clusters using a noble gas atmosphere. The simulations are performed using a many-body interaction scheme for the intra-cluster potential, while a pairwise Lennard-Jones potential is used to model the interaction between the noble gas and the clusters. In order to isolate different parameters determining the energy exchange efficiency, we have studied the energy transfer with respect to (i) impact parameter, (ii) cluster temperature, (iii) noble gas temperature, (iv) gas-metal interaction strength, (v) metal potential, and (vi) noble gas mass. With these results, we are able to estimate the number of collisions needed to equilibrate a cluster at a given gas temperature. Our estimates are confirmed by simulations of cluster cooling in a noble gas atmosphere. (C) 1987 American Institute of Physics.