Abstract
We have measured ultracold ionizing collision rates for three bosonic and and two fermionic and isotopes of xenon in the metastable state, for both spin-polarized and unpolarized samples. For unpolarized samples at temperatures above the p-wave centrifugal barrier we find that collision rates for all isotopes are identical. Quantum-statistical effects forbid s-wave collisions for spin-polarized fermions, giving rise to significant differences between bosonic and fermionic isotopes below the p-wave barrier. We present a technique for measuring collision rates at temperatures below and find that the ratio of polarized to unpolarized collision rates for fermions decreases by a factor of 2 at low temperatures, while the ratio for bosons increases by We find no evidence of an overall reduction in the collision rate for spin-polarized samples, as has been observed in metastable helium. These results are explained using a simple theoretical model of transmission and quantum reflection off long-range interatomic potentials.
- Received 20 July 1998
DOI:https://doi.org/10.1103/PhysRevA.59.1926
©1999 American Physical Society