Optical trapping of fermionic potassium for collisional studies

We report on trapping of fermionic 40K atoms in a red-detuned standing-wave optical trap, loaded from a magneto-optical trap. Typically, unpolarized samples of 106 atoms are loaded at a density of 1012 cm23 and a temperature of 65mK, and trapped for more than 1 s. The optical trap appears to be the proper environment for performing collisional measurements on the cold atomic sample. In particular, we measure the spherically averaged elastic collision rate by detecting the rethermalization following an intentional parametric heating of the atoms. We also measure spherically averaged inelastic two-body collision rates for atoms in the ground hyperfine states, through detection of trap losses.