Getting the elastic scattering length by observing inelastic collisions in ultracold metastable helium atoms
S Seidelin1, J Viana Gomes, R Hoppeler
1Laboratoire Charles Fabry de l'Institut d'Optique, UMR 8501 du CNRS, F-91403 Orsay, France.
Abstract:
We report an experiment measuring simultaneously the temperature and the flux of ions produced by a cloud of triplet metastable helium atoms at the Bose-Einstein critical temperature. The onset of condensation is revealed by a sharp increase of the ion flux during evaporative cooling. Combining our measurements with previous measurements of ionization in a pure Bose-Einstein condensate, we extract an improved value of the scattering length a=11.3(+2.5)(-1.0) nm. The analysis includes corrections that take into account the effect of atomic interactions on the critical temperature, and thus an independent measurement of the scattering length would allow a new test of these calculations.
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