Monte-Carlo simulations of the capture and cooling of alkali-metal atoms by a supersonic helium jet
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| Formato: | Preprint |
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2024
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| _version_ | 1866914652625043456 |
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| author | Glick, Jeremy Huntington, William Borysow, Michael Wen, Kevin Heinzen, Daniel Kłos, Jacek Tiesinga, Eite |
| author_facet | Glick, Jeremy Huntington, William Borysow, Michael Wen, Kevin Heinzen, Daniel Kłos, Jacek Tiesinga, Eite |
| contents | We present three-dimensional Monte-Carlo simulations of the capture of 1000 K $^7$Li or 500 K $^{87}$Rb atoms by a continuous supersonic $^4$He jet and show that intense alkali-metal beams form with narrow transverse and longitudinal velocity distributions. The nozzle creating the $^4$He jet is held at approximately 4 K. These conditions are similar to those in the cold $^7$Li source developed by some of us as described in [Phy. Rev. A 107, 013302 (2023)]. The simulations use differential cross-sections obtained from quantum scattering calculations of $^7$Li or $^{87}$Rb atoms with $^4$He atoms for relative collision energies between $k\times 1$ mK to $k\times 3000$ K, where $k$ is the Boltzmann constant. For collision energies larger than $\approx k\times 4$ K the collisions favor forward scattering, deflecting the $^7$Li or $^{87}$Rb atoms by no more than a few degrees. From the simulations, we find that about 1$\%$ of the lithium atoms are captured into the $^4$He jet, resulting in a lithium beam with a most probable velocity of about $210$ m/s and number densities on the order of $10^{8}$ cm$^{-3}$. Simulations predict narrow yet asymmetric velocity distributions which are verified by comparing to fluorescence measurements of the seeded $^7$Li atoms. We find agreement between simulated and experimentally measured seeded $^7$Li densities to be better than 50$\%$ across a range of $^4$He flow rates. We make predictions for capture efficiency and cooling of $^{87}$Rb by a supersonic $^4$He jet. The capture efficiency for $^{87}$Rb is expected to be similar to $^7$Li. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_13895 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Monte-Carlo simulations of the capture and cooling of alkali-metal atoms by a supersonic helium jet Glick, Jeremy Huntington, William Borysow, Michael Wen, Kevin Heinzen, Daniel Kłos, Jacek Tiesinga, Eite Atomic Physics We present three-dimensional Monte-Carlo simulations of the capture of 1000 K $^7$Li or 500 K $^{87}$Rb atoms by a continuous supersonic $^4$He jet and show that intense alkali-metal beams form with narrow transverse and longitudinal velocity distributions. The nozzle creating the $^4$He jet is held at approximately 4 K. These conditions are similar to those in the cold $^7$Li source developed by some of us as described in [Phy. Rev. A 107, 013302 (2023)]. The simulations use differential cross-sections obtained from quantum scattering calculations of $^7$Li or $^{87}$Rb atoms with $^4$He atoms for relative collision energies between $k\times 1$ mK to $k\times 3000$ K, where $k$ is the Boltzmann constant. For collision energies larger than $\approx k\times 4$ K the collisions favor forward scattering, deflecting the $^7$Li or $^{87}$Rb atoms by no more than a few degrees. From the simulations, we find that about 1$\%$ of the lithium atoms are captured into the $^4$He jet, resulting in a lithium beam with a most probable velocity of about $210$ m/s and number densities on the order of $10^{8}$ cm$^{-3}$. Simulations predict narrow yet asymmetric velocity distributions which are verified by comparing to fluorescence measurements of the seeded $^7$Li atoms. We find agreement between simulated and experimentally measured seeded $^7$Li densities to be better than 50$\%$ across a range of $^4$He flow rates. We make predictions for capture efficiency and cooling of $^{87}$Rb by a supersonic $^4$He jet. The capture efficiency for $^{87}$Rb is expected to be similar to $^7$Li. |
| title | Monte-Carlo simulations of the capture and cooling of alkali-metal atoms by a supersonic helium jet |
| topic | Atomic Physics |
| url | https://arxiv.org/abs/2401.13895 |