Physical review. B, Condensed matter

Lifetime of magnetically trapped ultracold atomic deuterium gas

J. M. V. A. Koelman, Henk T. C. Stoof, BOUDEWIJN J. VERHAAR, Jook T. M. Walraven

Published Nov 1, 1988• 13 citations

Abstract

We have calculated the magnetic dipolar spin-relaxation rates of magnetically trapped doubly-spin-polarized atomic deuterium gas. The results are expressed in a simple closed formula describing the dipolar-relaxation-limited stability in the Boltzmann ($T\ensuremath{\gg}{T}_{F}$), the degeneracy ($T\ensuremath{\ll}{T}_{F}$), and the crossover ($T\ensuremath{\simeq}{T}_{F}$) regimes. In the degeneracy regime we typically find lifetimes of some hours. We also discuss the dipolar decay of magnetically trapped spin-polarized fermionic alkali-metal atoms.

DOI: 10.1103/physrevb.38.9319

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Physical review. B, Condensed matter

Lifetime of magnetically trapped ultracold atomic deuterium gas

J. M. V. A. Koelman, Henk T. C. Stoof, BOUDEWIJN J. VERHAAR, Jook T. M. Walraven

Published Nov 1, 1988• 13 citations

Publisher

Abstract

T\ensuremath{\gg}{T}_{F}

), the degeneracy (

T\ensuremath{\ll}{T}_{F}

), and the crossover (

T\ensuremath{\simeq}{T}_{F}

) regimes. In the degeneracy regime we typically find lifetimes of some hours. We also discuss the dipolar decay of magnetically trapped spin-polarized fermionic alkali-metal atoms.

DOI: 10.1103/physrevb.38.9319

Related papers

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Physical Review LettersAug 10, 198748 citations

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Collisional properties of cold spin-polarized nitrogen gas: Theory, experiment, and prospects as a sympathetic coolant for trapped atoms and molecules

Timur V. Tscherbul, Jacek A. Kłos, A. Dalgarno +6 more

We report a combined experimental and theoretical study of collision-induced dipolar relaxation in a cold spin-polarized gas of atomic nitrogen (N). We use buffer gas cooling to create trapped samples of $^{14}\mathrm{N}$ and $^{15}\mathrm{N}$ atoms with densities $(5\ifmmode\pm\else\textpm\fi{}2)\ifmmode\times\else\texttimes\fi{}{10}^{12} {\mathrm{cm}}^{\ensuremath{-}3}$ and measure their magnetic relaxation rates at milli-Kelvin temperatures. These measurements, together with rigorous quantum scattering calculations based on accurate ab initio interaction potentials for the ${}^{7}{\ensuremath{\Sigma}}_{u}^{+}$ electronic state of ${\mathrm{N}}_{2}$ demonstrate that dipolar relaxation in $\mathrm{N}+\mathrm{N}$ collisions occurs at a slow rate of $~{10}^{\ensuremath{-}13} {\mathrm{cm}}^{3}$/s over a wide range of temperatures (1 mK to 1 K) and magnetic fields (10 mT to 2 T). The calculated dipolar relaxation rates are insensitive to small variations of the interaction potential and to the magnitude of the spin-exchange interaction, enabling the accurate calibration of the measured N atom density. We find consistency between the calculated and experimentally determined rates. Our results suggest that N atoms are promising candidates for future experiments on sympathetic cooling of molecules.We report a combined experimental and theoretical study of collision-induced dipolar relaxation in a cold spin-polarized gas of atomic nitrogen (N). We use buffer gas cooling to create trapped samples of $^{14}\mathrm{N}$ and $^{15}\mathrm{N}$ atoms with densities $(5\ifmmode\pm\else\textpm\fi{}2)\ifmmode\times\else\texttimes\fi{}{10}^{12} {\mathrm{cm}}^{\ensuremath{-}3}$ and measure their magnetic relaxation rates at milli-Kelvin temperatures. These measurements, together with rigorous quantum scattering calculations based on accurate ab initio interaction potentials for the ${}^{7}{\ensuremath{\Sigma}}_{u}^{+}$ electronic state of ${\mathrm{N}}_{2}$ demonstrate that dipolar relaxation in $\mathrm{N}+\mathrm{N}$ collisions occurs at a slow rate of $~{10}^{\ensuremath{-}13} {\mathrm{cm}}^{3}$/s over a wide range of temperatures (1 mK to 1 K) and magnetic fields (10 mT to 2 T). The calculated dipolar relaxation rates are insensitive to small variations of the interaction potential and to the magnitude of the spin-exchange interaction, enabling the accurate calibration of the measured N atom density. We find consistency between the calculated and experimentally determined rates. Our results suggest that N atoms are promising candidates for future experiments on sympathetic cooling of molecules.

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Spin-exchange and dipole relaxation rates in atomic hydrogen: Rigorous and simplified calculations

Henk T. C. Stoof, J. M. V. A. Koelman, BOUDEWIJN J. VERHAAR

Physical review. B, Condensed matterSep 1, 1988216 citations

T\ensuremath{\gg}{T}_{F}

), the degeneracy (

T\ensuremath{\ll}{T}_{F}

), and the crossover (

T\ensuremath{\simeq}{T}_{F}

) regimes. In the degeneracy regime we typically find lifetimes of some hours. We also discuss the dipolar decay of magnetically trapped spin-polarized fermionic alkali-metal atoms.

We have confined over 5\ifmmode\times\else\texttimes\fi{}

{10}^{12}

atoms of hydrogen in a static magnetic trap. The atoms are loaded into the trap by precooling with a dilution refrigerator. At operating densities near 1\ifmmode\times\else\texttimes\fi{}

{10}^{13}

${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ the gas is observed to be electron and nuclear polarized in the uppermost hyperfine state. The long lifetime of the trapped gas (over 20 min) suggests that it is thermally decoupled from the wall and has evaporatively cooled to a temperature of about 40 mK. The residual decay of the gas density is consistent with spin relaxation induced by dipolar interactions between atoms.

{T}_{c}

the rate constants have a discontinuous second derivative with respect to T. Below

{T}_{c}

they show a pronounced decrease relative to the extrapolated above-

{T}_{c}

values, the observation of which is a clear signal for the experimental realization of Bose-Einstein condensation.

^{14}\mathrm{N}

and

^{15}\mathrm{N}

atoms with densities $(5\ifmmode\pm\else\textpm\fi{}2)\ifmmode\times\else\texttimes\fi{}{10}^{12} {\mathrm{cm}}^{\ensuremath{-}3}$ and measure their magnetic relaxation rates at milli-Kelvin temperatures. These measurements, together with rigorous quantum scattering calculations based on accurate ab initio interaction potentials for the ${}^{7}{\ensuremath{\Sigma}}_{u}^{+}$ electronic state of

{\mathrm{N}}_{2}

demonstrate that dipolar relaxation in

\mathrm{N}+\mathrm{N}

collisions occurs at a slow rate of $~{10}^{\ensuremath{-}13} {\mathrm{cm}}^{3}$/s over a wide range of temperatures (1 mK to 1 K) and magnetic fields (10 mT to 2 T). The calculated dipolar relaxation rates are insensitive to small variations of the interaction potential and to the magnitude of the spin-exchange interaction, enabling the accurate calibration of the measured N atom density. We find consistency between the calculated and experimentally determined rates. Our results suggest that N atoms are promising candidates for future experiments on sympathetic cooling of molecules.