%0 Journal Article %J Physical Review A %D 2009 %T Collisional cooling of ultra-cold atom ensembles using Feshbach resonances %A L. Mathey %A Eite Tiesinga %A Paul S. Julienne %A Charles W. Clark %X We propose a new type of cooling mechanism for ultra-cold fermionic atom ensembles, which capitalizes on the energy dependence of inelastic collisions in the presence of a Feshbach resonance. We first discuss the case of a single magnetic resonance, and find that the final temperature and the cooling rate is limited by the width of the resonance. A concrete example, based on a p-wave resonance of $^{40}$K, is given. We then improve upon this setup by using both a very sharp optical or radio-frequency induced resonance and a very broad magnetic resonance and show that one can improve upon temperatures reached with current technologies. %B Physical Review A %V 80 %8 2009/9/8 %G eng %U http://arxiv.org/abs/0903.2568v1 %N 3 %! Phys. Rev. A %R 10.1103/PhysRevA.80.030702