Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physica Scripta

Fine Structure in Cold Collisions of Spin-Polarized H(2s) Atoms

S. Jonsell, Robert C. Forrey, Alejandro Sáenz, Piotr Froelich, A. Dalgarno

Published Jan 1, 2004• 1 citation
Publisher

Abstract

We have calculated cross sections and rate coefficients for elastic scattering, ionization, and double excitation transfer in collision of two hydrogen atoms in the 2s state. We find that for collision energies between 5 × 10-10 a.u. and 10-6 a.u. elastic scattering has the largest cross section. For temperatures below 0.02 K ionization is the dominant loss process, while for higher temperatures double excitation transfer dominates. Our results for the total loss rate are found to be within a factor 2 or 3 of the error bars of recent measurements.

DOI
10.1238/physica.topical.110a00299

Related papers

Cold collisions of spin-polarized metastable hydrogen atoms

Robert C. Forrey, S. Jonsell, Alejandro Sáenz +2 more

Cross sections and rate coefficients for collisions of two spin-polarized metastable hydrogen atoms are calculated at low energies and temperatures using complex scaling and Feshbach projection methods for the determination of the molecular potential-energy curves. The inclusion of the Lamb shift and fine-structure splitting of the excited $n=2$ atoms leads to an attractive van der Waals potential for two ${2s}_{1/2}$ atoms with an exceptionally large coefficient. The quenching of the metastable atoms is dominated at temperatures below 20 mK by ionization. The calculated values for the total loss rate coefficient at 87 \ensuremath{\mu}K and 230 \ensuremath{\mu}K are within a factor of 2 or 3 of the error bars of recent measurements of metastable loss rate coefficients.

Physical Review A•Apr 10, 2003•15 citations

Elastic and spin-changing cross sections of spin-polarized atomic tritium

M. G. Elliott, B. J. P. Jones

The rates of elastic and inelastic scattering processes of spin-polarized atomic tritium are vital inputs for the design and operation of experiments using cold, magnetically trapped tritium atoms. Elastic scattering dominates the total cross section and dictates the thermophysical properties of the vapor, determining the efficiency of magnetic evaporative cooling and the fluid dynamical properties of the trapped atom cloud. Spin-changing cross sections in both exchange and dipolar channels determine the trap lifetime of the various hyperfine states, imposing constraints on the required atomic tritium supply rate to maintain a given trap density. Motivated by the needs of next-generation spectrometers that will study the tritium beta end point to infer the mass of the neutrino, we present new calculations of the elastic, spin-exchange, and dipolar cross sections for spin-polarized atomic tritium. Cross sections and rate constants are reported for magnetic field strengths of 0--10 T and temperatures from 0 to 100 K in all relevant Zeeman-hyperfine channels for both tritium and hydrogen. Results are benchmarked against past calculations for atomic hydrogen and the limited available results for tritium, and extend far into the regimes where past calculations have not been available.

arXiv:2509.13426•Physical Review A•Nov 20, 2025•1 citation

Spin polarization transfer in ground and metastable helium atom collisions

D. Vrinceanu, H. R. Sadeghpour

Cross sections and rate constants for total elastic, diffusion and transfer of metastability for collisions between He(11S)–He(23S) and He(11S)–He(23P) atoms over a wide range of energies and temperatures are presented. The rate constant for spin metastability excitation in He(11S)–He(23P) collision is several orders of magnitude larger than that for He(11S)–He(23S) collision at cold temperatures, due to attractive 3Πg potential interaction.

New Journal of Physics•Jun 28, 2010•7 citations

Elastic and Inelastic Collisions of Cold Spin-Polarized C133s Atoms

Paul J. Leo, Eite Tiesinga, Paul S. Julienne +3 more

We present theoretical calculations of thermally averaged elastic cross sections and spin-relaxation rate coefficients in the temperature range 0.1 to $300\ensuremath{\mu}\mathrm{K}$ for magnetically trapped, doubly polarized cesium atoms. The calculations reproduce the recent experimental results of Arndt et al. (1997) and S\"oding et al. (1998) for cases where the ${a}^{3}{\ensuremath{\Sigma}}_{u}$ ground state potential of $\mathrm{Cs}{}_{2}$ possesses a large scattering length ( $|{A}_{3}|>35\mathrm{nm}$) and the magnitude of the second-order spin-orbit interaction is scaled to reproduce room temperature scattering data.

Physical Review Letters•Aug 17, 1998•53 citations

Collisions of cold antiprotonic helium atoms and ions with ordinary helium atoms

Grigory Ya. Korenman, S. N. Yudin

We consider two types of collisional processes with excited antiprotonic helium systems. (i) Transitions between hyperfine structure sublevels in ( He + ) n LFJ are considered at T ≤ 25 K using the coupled-channels method and a model of scalar and tensor interactions between antiprotonic and ordinary He atoms. Inelastic cross sections for the single and double spin-flip transitions are less than elastic ones by four and seven orders of magnitude, respectively. The cross sections show a resonance behaviour at E ∼ 1–4 K, and therefore the relaxation rates, density shift and broadening of the M1 spectral lines decrease with increasing temperature from 3 to 25 K. (ii) Stark transitions and induced annihilation during collisions of the ( He 2+ ) nl ion with He atoms at E ∼ 10 K are considered for all l -states at n ∼ 30 in the framework of the coupled-channels method. In order to take into account complex energy shifts of the ns and np -states, we introduce modified boundary conditions in these channels. The main contribution to elastic scattering, Stark transitions and induced annihilations during collisions comes from the long-range polarization interaction. Admixtures of ns and np -states to nl -states ( l ≥ 2) during collisions induce the effective annihilation cross sections for the initial l up to 15, but don't affect the Stark cross sections for states with nearly-circular orbits. The calculated values for both types of processes are compatible with recent experimental data.

Journal of Physics Conference Series•Nov 1, 2007•9 citations

Collisional Properties of Cold Spin-Polarized Metastable Neon Atoms

Peter Spoden, M. Zinner, Norbert Herschbach +3 more

We measure the rates of elastic and inelastic two-body collisions of cold spin-polarized neon atoms in the metastable $^{3}P_{2}$ state for $^{20}\mathrm{Ne}$ and $^{22}\mathrm{Ne}$ in a magnetic trap. From particle loss, we determine the loss parameter of inelastic collisions $\ensuremath{\beta}=6.5(18)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ for $^{20}\mathrm{Ne}$ and $\ensuremath{\beta}=1.2(3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ for $^{22}\mathrm{Ne}$. 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 $a=\ensuremath{-}180(40){a}_{0}$ for $^{20}\mathrm{Ne}$ and $a=+{150}_{\ensuremath{-}50}^{+80}{a}_{0}$ for $^{22}\mathrm{Ne}$, where ${a}_{0}=0.0529\text{ }\text{ }\mathrm{nm}$.

arXiv:quant-ph/0502020•Physical Review Letters•Jun 7, 2005•25 citations
We have calculated cross sections and rate coefficients for elastic scattering, ionization, and double excitation transfer in collision of two hydrogen atoms in the 2s state. We find that for collision energies between 5 × 10-10 a.u. and 10-6 a.u. elastic scattering has the largest cross section. For temperatures below 0.02 K ionization is the dominant loss process, while for higher temperatures double excitation transfer dominates. Our results for the total loss rate are found to be within a factor 2 or 3 of the error bars of recent measurements.
Cross sections and rate coefficients for collisions of two spin-polarized metastable hydrogen atoms are calculated at low energies and temperatures using complex scaling and Feshbach projection methods for the determination of the molecular potential-energy curves. The inclusion of the Lamb shift and fine-structure splitting of the excited n=2n=2n=2 atoms leads to an attractive van der Waals potential for two 2s1/2{2s}_{1/2}2s1/2​ atoms with an exceptionally large coefficient. The quenching of the metastable atoms is dominated at temperatures below 20 mK by ionization. The calculated values for the total loss rate coefficient at 87 \ensuremath{\mu}K and 230 \ensuremath{\mu}K are within a factor of 2 or 3 of the error bars of recent measurements of metastable loss rate coefficients.
The rates of elastic and inelastic scattering processes of spin-polarized atomic tritium are vital inputs for the design and operation of experiments using cold, magnetically trapped tritium atoms. Elastic scattering dominates the total cross section and dictates the thermophysical properties of the vapor, determining the efficiency of magnetic evaporative cooling and the fluid dynamical properties of the trapped atom cloud. Spin-changing cross sections in both exchange and dipolar channels determine the trap lifetime of the various hyperfine states, imposing constraints on the required atomic tritium supply rate to maintain a given trap density. Motivated by the needs of next-generation spectrometers that will study the tritium beta end point to infer the mass of the neutrino, we present new calculations of the elastic, spin-exchange, and dipolar cross sections for spin-polarized atomic tritium. Cross sections and rate constants are reported for magnetic field strengths of 0--10 T and temperatures from 0 to 100 K in all relevant Zeeman-hyperfine channels for both tritium and hydrogen. Results are benchmarked against past calculations for atomic hydrogen and the limited available results for tritium, and extend far into the regimes where past calculations have not been available.
We present theoretical calculations of thermally averaged elastic cross sections and spin-relaxation rate coefficients in the temperature range 0.1 to $300\ensuremath{\mu}\mathrm{K}$ for magnetically trapped, doubly polarized cesium atoms. The calculations reproduce the recent experimental results of Arndt et al. (1997) and S\"oding et al. (1998) for cases where the ${a}^{3}{\ensuremath{\Sigma}}_{u}$ ground state potential of Cs2\mathrm{Cs}{}_{2}Cs2​ possesses a large scattering length ( ∣A3∣>35nm|{A}_{3}|>35\mathrm{nm}∣A3​∣>35nm) and the magnitude of the second-order spin-orbit interaction is scaled to reproduce room temperature scattering data.
We consider two types of collisional processes with excited antiprotonic helium systems. (i) Transitions between hyperfine structure sublevels in ( He + ) n LFJ are considered at T ≤ 25 K using the coupled-channels method and a model of scalar and tensor interactions between antiprotonic and ordinary He atoms. Inelastic cross sections for the single and double spin-flip transitions are less than elastic ones by four and seven orders of magnitude, respectively. The cross sections show a resonance behaviour at E ∼ 1–4 K, and therefore the relaxation rates, density shift and broadening of the M1 spectral lines decrease with increasing temperature from 3 to 25 K. (ii) Stark transitions and induced annihilation during collisions of the ( He 2+ ) nl ion with He atoms at E ∼ 10 K are considered for all l -states at n ∼ 30 in the framework of the coupled-channels method. In order to take into account complex energy shifts of the ns and np -states, we introduce modified boundary conditions in these channels. The main contribution to elastic scattering, Stark transitions and induced annihilations during collisions comes from the long-range polarization interaction. Admixtures of ns and np -states to nl -states ( l ≥ 2) during collisions induce the effective annihilation cross sections for the initial l up to 15, but don't affect the Stark cross sections for states with nearly-circular orbits. The calculated values for both types of processes are compatible with recent experimental data.
We measure the rates of elastic and inelastic two-body collisions of cold spin-polarized neon atoms in the metastable 3P2^{3}P_{2}3P2​ state for 20Ne^{20}\mathrm{Ne}20Ne and 22Ne^{22}\mathrm{Ne}22Ne in a magnetic trap. From particle loss, we determine the loss parameter of inelastic collisions $\ensuremath{\beta}=6.5(18)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ for 20Ne^{20}\mathrm{Ne}20Ne and $\ensuremath{\beta}=1.2(3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ for 22Ne^{22}\mathrm{Ne}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 $a=\ensuremath{-}180(40){a}_{0}$ for 20Ne^{20}\mathrm{Ne}20Ne and $a=+{150}_{\ensuremath{-}50}^{+80}{a}_{0}$ for 22Ne^{22}\mathrm{Ne}22Ne, where a0=0.0529  nm{a}_{0}=0.0529\text{ }\text{ }\mathrm{nm}a0​=0.0529  nm.