[en] We report on measurements of three-body recombination at negative scattering lengths in an ultracold cesium gas. Magnetic tuning of the scattering length by means of a Feshbach resonance is used to investigate a strong loss peak resulting from an Efimov resonance. The position of maximum loss shifts significantly when the temperature of the gas is varied, providing quantitative insight into the evolution of an Efimov state into a triatomic continuum resonance. We compare our measurements with several calculations that extend the theory of three-body recombination to non-zero collision energies. In our apparatus we prepare an ultracold gas of cesium atoms in an optical surface trap. The main part is a glass cell with an integrated prism, providing good optical access and accurate and fast control of the magnetic field. The atoms are located a few micrometers above the dielectric prism surface. Raman sideband and Sisyphus cooling are applied to reach temperatures of a few μK. We further reduce the temperature below 100 nK via evaporative cooling. We then apply different magnetic fields and measure the rate of three-body recombination

[en] We report on measurements of three-body recombination at negative scattering lengths in an ultracold cesium gas. Magnetic tuning of the scattering length by means of a Feshbach resonance is used to investigate a strong loss peak resulting from an Efimov resonance. The position of maximum loss shifts significantly when the temperature of the gas is varied, providing quantitative insight into the evolution of an Efimov state into a triatomic continuum resonance. We compare our measurements with several calculations that extend the theory of three-body recombination to non-zero collision energies. In our apparatus we prepare an ultracold gas of cesium atoms in an optical surface trap. The main part is a glass cell with an integrated prism, providing good optical access and accurate and fast control of the magnetic field. The atoms are located a few micrometers above the dielectric prism surface. Raman sideband and Sisyphus cooling are applied to reach temperatures of a few μK. We further reduce the temperature below 100 nK via evaporative cooling. We then apply different magnetic fields and measure the rate of three-body recombination