We measure the rates of elastic and inelastic two-body collisions of cold spin-polarized neon atoms in the metastable 3P2 state for 20Ne and 22Ne in a magnetic trap. From particle loss, we determine the loss parameter of inelastic collisions beta=6.5(18) x 10(-12) cm(3) s(-1) for 20Ne and beta=1.2(3) x 10(-11) cm(3) s(-1) for 22Ne. These losses are caused by ionizing (i.e., Penning) collisions and occur less frequently than for unpolarized atoms. This proves the suppression of Penning ionization due to spin polarization. From cross-dimensional relaxation measurements, we obtain elastic scattering lengths of a=-180(40)a(0) for 20Ne and a = +150(+80)(-50)a(0) for 22Ne, where a(0)=0.0529 nm.

The lifetime of the metastable 3 P2 state of neon has been determined to 14.70(13) s (decay rate 0.06801(62) s −1 ) by measuring the decay in fluorescence of an ensemble of 20 Ne atoms trapped in a magneto-optical trap (MOT). Due to low background gas pressure (p < 5 × 10 −11 mbar) and low relative excitation to the 3 D3 state (0.5 % excitation probability) operation only small corrections have to be included in the lifetime extrapolation. Together with a careful analysis of residual loss mechanisms in the MOT a lifetime determination to high precision is achieved.PACS numbers: 32.70. Cs, 32.70.Fw, 32.80.Pj In contrast to its importance for various active fields of research covering such a wide range as atomic physics, quantum optics, and nuclear physics, there still has been no measurement of the natural lifetime of the metastable 3 P 2 state [1] of neon with sufficient precision. A selection of research activities profiting from an improved measurement include the quest for Bose-Einstein condensation (BEC) of metastable neon, advanced atomic structure calculations, the investigation of ultracold collisions, and even precision tests of the electroweak theory being currently persued by investigating the nuclear decay of an optically trapped sample of 19 Ne in the 3 P 2 state [2].Ongoing research directed towards BEC of metastable neon atoms in the 3 P 2 state [3, 4] clearly will benefit from an accurate knowledge of the state's lifetime. This includes the optimization of the production process as well as the study of collision processes such as Penningionization [5] and elastic s-wave scattering. Exciting new physics complementing the work on metastable helium [6,7] can be expected for a 3 P 2 neon condensate. We would like to point out the study of higher-order correlations [8] and the intriguing possibility of a modification of the 3 P 2 decay rate due to the high phase-space density or the phase coherence in a BEC [9].Significant advance in atomic structure calculations has already been and will be further triggered [10] by the work presented here. To date only a preliminary experimental value of 22 s for the 3 P 2 lifetime of neon exists [11] with no detailed investigations having been performed [12]. A precise determination of the lifetime will put a more stringent test on theory. For most rare-gas atoms, the 3 P 2 lifetime depends sensitively on electron correlations and relativistic corrections. The latter have only a minor effect for the case of neon, making neon specifically interesting for a critcal test of electron correlations. In addition, our measurement will close the chain of 3 P 2 lifetime measurements for rare-gas atoms beyond helium performed in recent years for Ar ( input for a detailed systematic investigation of the Zdependence of metastable lifetimes. An accurate experimental determination of the 3 P 2 lifetimes of rare-gas atoms other than helium has only been achievable by the ability to prepare cold atom samples in a MOT [11,13,14,15]. For a precision lifetime measurement, the coupli...

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