Sympathetic cooling of two atomic isotopes is experimentally investigated. Using forced evaporation of a bosonic ${}^7\mathrm{Li}$ gas in a magnetic trap, a sample of $1.3\times {10}^5$ ${}^6\mathrm{Li}$ fermions has been sympathetically cooled to $9\left(3\right)\mathrm{}\hspace{0.5em}\mu \mathrm{K},$ corresponding to $2.2\left(0.8\right)\mathrm{}$ times the Fermi temperature. The measured rate constant for two-body inelastic collisions of the ${}^7\mathrm{Li}$ $|2,2〉$ state at low magnetic field is ${1.0}_{-0.5}^{+0.8\mathrm{}}\times {10}^{-14}\hspace{0.5em}{\mathrm{cm}}^3{\mathrm{s}}^{-1}.$

• Received 16 November 2000

DOI:https://doi.org/10.1103/PhysRevA.64.011402