Physical Review A

s-wave elastic collisions between cold ground-state Rb87 atoms

Nathan R. Newbury, Christopher J. Myatt, Carl Wieman

Published Apr 1, 1995• 51 citations

Abstract

We have measured the elastic-scattering cross section of $^{87}\mathrm{Rb}$ atoms in the \ensuremath{\Vert}F=1,${\mathit{m}}_{\mathit{F}}$=-1〉 ground state at 25 \ensuremath{\mu}K. The cross section is almost purely s wave at these temperatures and has a value of (5.4\ifmmode\pm\else\textpm\fi{}1.3)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}12}$ ${\mathrm{cm}}^{2}$. We have searched for the predicted Feshbach-type resonances in the elastic cross section [Tiesinga et al., Phys. Rev. A 46, 1167 (1992)] as a function of magnetic field. There are no resonances with a magnetic-field width \ensuremath{\ge}2 G over a magnetic-field range of 15--540 G.

DOI: 10.1103/physreva.51.r2680

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Characterization of elastic scattering near a Feshbach resonance in 87Rb

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Cold magnetically trapped 2Dg scandium atoms. II. Scattering dynamics

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Physical Review A

s-wave elastic collisions between cold ground-state Rb87 atoms

Nathan R. Newbury, Christopher J. Myatt, Carl Wieman

Published Apr 1, 1995• 51 citations

Publisher

Abstract

We have measured the elastic-scattering cross section of

^{87}\mathrm{Rb}

atoms in the \ensuremath{\Vert}F=1,

{\mathit{m}}_{\mathit{F}}

=-1〉 ground state at 25 \ensuremath{\mu}K. The cross section is almost purely s wave at these temperatures and has a value of (5.4\ifmmode\pm\else\textpm\fi{}1.3)\ifmmode\times\else\texttimes\fi{}

{10}^{\mathrm{\ensuremath{-}}12}

{\mathrm{cm}}^{2}

. We have searched for the predicted Feshbach-type resonances in the elastic cross section [Tiesinga et al., Phys. Rev. A 46, 1167 (1992)] as a function of magnetic field. There are no resonances with a magnetic-field width \ensuremath{\ge}2 G over a magnetic-field range of 15--540 G.

DOI: 10.1103/physreva.51.r2680

Related papers

Characterization of elastic scattering near a Feshbach resonance in 87Rb

Thomas Volz, Stephan Dürr, Sebastian Ernst +2 more

The s-wave scattering length for elastic collisions between ${}^{87}\mathrm{Rb}$ atoms in the state $|{f,m}_{f}〉=|1,1〉$ is measured in the vicinity of a Feshbach resonance near 1007 G. Experimentally, the scattering length is determined from the mean-field-driven expansion of a Bose-Einstein condensate in a homogeneous magnetic field. The scattering length is measured as a function of the magnetic field and agrees with the theoretical expectation. The width of the resonance is determined to be 0.20(3) G, the position of the zero crossing of the scattering length is found at 1007.60(3) G.The s-wave scattering length for elastic collisions between ${}^{87}\mathrm{Rb}$ atoms in the state $|{f,m}_{f}〉=|1,1〉$ is measured in the vicinity of a Feshbach resonance near 1007 G. Experimentally, the scattering length is determined from the mean-field-driven expansion of a Bose-Einstein condensate in a homogeneous magnetic field. The scattering length is measured as a function of the magnetic field and agrees with the theoretical expectation. The width of the resonance is determined to be 0.20(3) G, the position of the zero crossing of the scattering length is found at 1007.60(3) G.

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Measurement of elastic cross section for cold cesium collisions

S. A. Hopkins, S. C. Webster, J. Arlt +4 more

We have measured the time taken for a magnetically trapped cloud of cold cesium atoms in the ${(F=3,m}_{F}=\ensuremath{-}3)$ ground state to rethermalize from a nonequilibrium spatial and velocity distribution. From these measurements we infer the dependences of the elastic scattering cross section on temperature and magnetic field in the ranges $1\ensuremath{-}30\ensuremath{\mu}\mathrm{K}$ and 0.05--2.0 mT, respectively. We determine a lower bound on the magnitude of the $(3,\ensuremath{-}3)+(3,\ensuremath{-}3)$ s-wave scattering length of ${940a}_{0}.$ We have measured the time taken for a magnetically trapped cloud of cold cesium atoms in the ${(F=3,m}_{F}=\ensuremath{-}3)$ ground state to rethermalize from a nonequilibrium spatial and velocity distribution. From these measurements we infer the dependences of the elastic scattering cross section on temperature and magnetic field in the ranges $1\ensuremath{-}30\ensuremath{\mu}\mathrm{K}$ and 0.05--2.0 mT, respectively. We determine a lower bound on the magnitude of the $(3,\ensuremath{-}3)+(3,\ensuremath{-}3)$ s-wave scattering length of ${940a}_{0}.$

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Resonant Magnetic Field Control of Elastic Scattering in Cold R 85 b

Jacob Roberts, N. R. Claussen, James P. Burke +3 more

A magnetic field-dependent Feshbach resonance has been observed in the elastic scattering collision rate between atoms in the $F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2,M\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}2$ state of ${}^{85}\mathrm{Rb}$ . Changing the magnetic field by several Gauss caused the collision rate to vary by a factor of 1 ${0}^{4}$ , and the sign of the scattering length could be reversed. The resonance peak is at 155.2(4) G and its width is 11.6(5) G. From these results we extract much improved values for the three quantities that characterize the interaction potential: The van der Waals coefficient ${C}_{6}$ , the singlet scattering length ${a}_{S}$ , and the triplet scattering length ${a}_{T}$ .A magnetic field-dependent Feshbach resonance has been observed in the elastic scattering collision rate between atoms in the $F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2,M\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}2$ state of ${}^{85}\mathrm{Rb}$. Changing the magnetic field by several Gauss caused the collision rate to vary by a factor of 1${0}^{4}$, and the sign of the scattering length could be reversed. The resonance peak is at 155.2(4) G and its width is 11.6(5) G. From these results we extract much improved values for the three quantities that characterize the interaction potential: The van der Waals coefficient ${C}_{6}$, the singlet scattering length ${a}_{S}$, and the triplet scattering length ${a}_{T}$.

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Resonant magnetic field control of elastic scattering of cold 85Rb

Jacob Roberts, N. R. Claussen, Burke,, James P. +3 more

A magnetic field dependent Feshbach resonance has been observed in the elastic scattering collision rate between atoms in the F = 2, M = -2 state of 85 Rb. Changing the magnetic field by several Gauss caused the collision rate to vary by a factor of 10,000, and the sign of the scattering length could be reserved. The resonance peak is at 155.2(4) G and its width is 11.6(5) G. From these results we extract much improved values for the three quantities that characterize the interaction porential: the van der Waals coefficient C6, the singlet scattering length, and the triplet scattering length.A magnetic field dependent Feshbach resonance has been observed in the elastic scattering collision rate between atoms in the F = 2, M = -2 state of 85 Rb. Changing the magnetic field by several Gauss caused the collision rate to vary by a factor of 10,000, and the sign of the scattering length could be reserved. The resonance peak is at 155.2(4) G and its width is 11.6(5) G. From these results we extract much improved values for the three quantities that characterize the interaction porential: the van der Waals coefficient C6, the singlet scattering length, and the triplet scattering length.

arXiv:physics/9808018Aug 14, 199815 citations

Cold magnetically trapped 2Dg scandium atoms. II. Scattering dynamics

Tijs Karman, Gerrit C. Groenenboom

The binary collision dynamics of ${}^{2}{D}_{g,3/2}$ ground state scandium atoms is studied from first principles. We employ 30 coupled diabatic ab initio potentials in a coupled-channels study of the scattering dynamics of cold and ultracold scandium atoms in external magnetic fields. Due to the long-ranged magnetic dipolar interaction, the field dependence of the cross section does not follow the threshold laws derived by Volpi and Bohn [Phys. Rev. A 65, 052712 (2002)]. In the field-free case, the near-threshold cross section is independent of the collision energy, and hence the cross section does not follow the well-established Wigner threshold laws. The observed threshold behavior is explained in the Born approximation. For energies above $1\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{K}$, inelastic collisions are driven by the anisotropic nonrelativistic electronic interaction. For energies below $100\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{K}$, the ratio of elastic-to-inelastic collisions is likely to be favorable for evaporative cooling. Both anisotropy in the long-range interaction and in the short-range potential contribute to large cross sections for inelastic collisions at higher energies and lead to a small ratio of elastic-to-inelastic collisions. This is in agreement with the large rates for Zeeman relaxation of submerged-shell atoms observed experimentally. The effect of the uncertainty in the ab initio potential is sampled by scaling the reduced mass and is found to have little influence on the conclusions drawn from this work.The binary collision dynamics of ${}^{2}{D}_{g,3/2}$ ground state scandium atoms is studied from first principles. We employ 30 coupled diabatic ab initio potentials in a coupled-channels study of the scattering dynamics of cold and ultracold scandium atoms in external magnetic fields. Due to the long-ranged magnetic dipolar interaction, the field dependence of the cross section does not follow the threshold laws derived by Volpi and Bohn [Phys. Rev. A 65, 052712 (2002)]. In the field-free case, the near-threshold cross section is independent of the collision energy, and hence the cross section does not follow the well-established Wigner threshold laws. The observed threshold behavior is explained in the Born approximation. For energies above $1\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{K}$, inelastic collisions are driven by the anisotropic nonrelativistic electronic interaction. For energies below $100\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{K}$, the ratio of elastic-to-inelastic collisions is likely to be favorable for evaporative cooling. Both anisotropy in the long-range interaction and in the short-range potential contribute to large cross sections for inelastic collisions at higher energies and lead to a small ratio of elastic-to-inelastic collisions. This is in agreement with the large rates for Zeeman relaxation of submerged-shell atoms observed experimentally. The effect of the uncertainty in the ab initio potential is sampled by scaling the reduced mass and is found to have little influence on the conclusions drawn from this work.

Physical Review ANov 5, 20146 citations

We have measured the elastic-scattering cross section of

^{87}\mathrm{Rb}

atoms in the \ensuremath{\Vert}F=1,

{\mathit{m}}_{\mathit{F}}

=-1〉 ground state at 25 \ensuremath{\mu}K. The cross section is almost purely s wave at these temperatures and has a value of (5.4\ifmmode\pm\else\textpm\fi{}1.3)\ifmmode\times\else\texttimes\fi{}

{10}^{\mathrm{\ensuremath{-}}12}

{\mathrm{cm}}^{2}

The s-wave scattering length for elastic collisions between

{}^{87}\mathrm{Rb}

atoms in the state

|{f,m}_{f}〉=|1,1〉

is measured in the vicinity of a Feshbach resonance near 1007 G. Experimentally, the scattering length is determined from the mean-field-driven expansion of a Bose-Einstein condensate in a homogeneous magnetic field. The scattering length is measured as a function of the magnetic field and agrees with the theoretical expectation. The width of the resonance is determined to be 0.20(3) G, the position of the zero crossing of the scattering length is found at 1007.60(3) G.

{940a}_{0}.

We report extensions and corrections to the measurement of the Feshbach resonance in

{}^{85}\mathrm{Rb}

cold atom collisions reported earlier [J. L. Roberts et al., Phys. Rev. Lett. 81, 5109 (1998)]. In addition to a better determination of the position of the resonance peak [154.9(4) G] and its width [11.0(4) G], improvements in our techniques now allow the measurement of the absolute size of the elastic-scattering rate. This provides a measure of the s-wave scattering length as a function of magnetic field near the Feshbach resonance and constrains the Rb-Rb interaction potential.

{}^{85}\mathrm{Rb}

. Changing the magnetic field by several Gauss caused the collision rate to vary by a factor of 1

{0}^{4}

, and the sign of the scattering length could be reversed. The resonance peak is at 155.2(4) G and its width is 11.6(5) G. From these results we extract much improved values for the three quantities that characterize the interaction potential: The van der Waals coefficient

{C}_{6}

, the singlet scattering length

{a}_{S}

, and the triplet scattering length

{a}_{T}

The binary collision dynamics of

{}^{2}{D}_{g,3/2}

ground state scandium atoms is studied from first principles. We employ 30 coupled diabatic ab initio potentials in a coupled-channels study of the scattering dynamics of cold and ultracold scandium atoms in external magnetic fields. Due to the long-ranged magnetic dipolar interaction, the field dependence of the cross section does not follow the threshold laws derived by Volpi and Bohn [Phys. Rev. A 65, 052712 (2002)]. In the field-free case, the near-threshold cross section is independent of the collision energy, and hence the cross section does not follow the well-established Wigner threshold laws. The observed threshold behavior is explained in the Born approximation. For energies above $1\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{K}$, inelastic collisions are driven by the anisotropic nonrelativistic electronic interaction. For energies below $100\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{K}$, the ratio of elastic-to-inelastic collisions is likely to be favorable for evaporative cooling. Both anisotropy in the long-range interaction and in the short-range potential contribute to large cross sections for inelastic collisions at higher energies and lead to a small ratio of elastic-to-inelastic collisions. This is in agreement with the large rates for Zeeman relaxation of submerged-shell atoms observed experimentally. The effect of the uncertainty in the ab initio potential is sampled by scaling the reduced mass and is found to have little influence on the conclusions drawn from this work.