Rethermalizing collisions between magnetically trapped metastable neon atoms

The successful Bose-Einstein Condensation (BEC) of alkali atoms has stimulated several groups to extend the range to metastable rare gas atoms. In 2001 this resulted in the achievement of BEC with metastable helium atoms (He^*) [1,2]. The only other rare gas atom suitable for achieving BEC is neon. The goal of our group is BEC of metastable neon (Ne^*). A condensate of metastable rare gas atoms is of special interest because their large internal energy enables real time diagnostics of the sample during condensation, giving new insight into the dynamics of the phase transition. Crucial for achieving BEC is a large (positive) scattering length. For He^* a good estimate of the order of magnitude of the scattering length was known. For neon no such theoretical estimate exists, therefore, experimental data on the value of the scattering length is necessary to determine whether or not BEC is feasible for Ne^*. In recent thermalization experiments involving two RF-knives, similar to the scheme used by Aspect et al. [3], we have observed rethermalizing collisions in our magnetic trap. Moreover, preliminary measurements point in the direction of a large absolute value of the scattering length. In this presentation we will discuss these thermalization experiments, and hope to present a value of the scattering length. [1] A. Robert et al., Science 292, 461 (2001). [2] F.P. Dos-Santos et al., Phys. Rev. Lett. 86, 3459 (2001). [3] A. Browaeys et al., Phys. Rev. A. 64, 034703 (2001).