Quantum Scattering in a Juggling Atomic Fountain

Ronald Legere and Kurt Gibble Department of Physics, Yale University, New Haven, Connecticut 06520-8120 (Received 19 August 1998) We demonstrate a juggling atomic fountain by launching two laser-cooled balls of 133Cs atoms in rapid succession. The atoms collide near the top of the fountain and, by varying the delay between launches, we scan the collision energy from 19 to 150 mK. We measure the differential scattering cross section and isolate the contributions from different partial waves including their interferences. We observe the s-wave energy dependence and the p-wave scattering threshold. We infer a triplet s-wave scattering length of 2400a0 and a p wave of s2107a0d for jF ­ 4, m ­ 4l 1 j3, 3l. [S0031-9007(98)08031-4]