Collisional properties of sympathetically cooled ${}^{39}$K

Abstract

We report the experimental evidence of the sympathetic cooling of ${}^{39}$K with ${}^{87}$Rb down to 1 $\mu$K, obtained in a novel tight confining magnetic trap. This allowed us to perform the first direct measurement of the elastic cross section of ${}^{39}$K below 50 $\mu$K. The result obtained for the triplet scattering length, $a_T=-51(7)$ Bohr radii, agrees with previous results derived from photoassociation spectra and from Feshbach spectroscopy of ${}^{40}$K.

7 pages, 4 figures, submitted to Phys. Rev. A