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Limit on suppression of ionization in metastable neon traps due to long-range anisotropy

1998; American Physical Society; Volume: 58; Issue: 5 Linguagem: Inglês

10.1103/physreva.58.3673

1538-4446

M. R. Doery, E.J.D. Vredenbregt, S. S. Op de Beek, H. C. W. Beijerinck, B. J. Verhaar,

Quantum, superfluid, helium dynamics

This paper investigates the possibility of suppressing the ionization rate in a magnetostatic trap of metastable neon atoms by spin-polarizing the atoms. Suppression of the ionization is critical for the possibility of reaching Bose-Einstein condensation with such atoms. We estimate the relevant long-range interactions for the system, consisting of electric quadrupole-quadrupole and dipole-induced dipole terms, and develop short-range potentials based on the ${\mathrm{Na}}_{2}$ singlet and triplet potentials. The autoionization widths of the system are also calculated. With these ingredients we calculate the ionization rate for spin-polarized and for spin-isotropic samples, caused by anisotropy of the long-range interactions. We find that spin polarization may allow for four orders of magnitude suppression of the ionization rate for Ne. The results depend sensitively on a precise knowledge of the interaction potentials, however, pointing out the need for experimental input. The same model gives a suppression ratio close to unity for metastable xenon in accordance with experimental results, due to a much increased anisotropy in this case.