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arXiv · 2105.06904

Positron cooling via inelastic collisions in CF$_4$ and N$_2$ gases

A. R. Swann·D. G. Green
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Abstract

Positron cooling via inelastic collisions in CF$_4$ and N$_2$ gases is simulated, including positron-positron interactions. Owing to the molecular symmetries, cooling is assumed to be chiefly due to energy loss via vibrational (rotational) excitations for CF$_4$ (N$_2$). For CF$_4$, it is found that the inclusion of the dipole-inactive $ν_1$ mode, in addition to the dipole-active modes $ν_3$ and $ν_4$, can provide room-temperature thermalization and an accurate cooling timescale. Combination cooling enabled by the $ν_1$ mode, and positron-positron interactions both contribute to the Maxwellianization of the positron momentum distribution. For both gases the evolution of the positron temperature is found to be in excellent agreement with experiment.

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A. R. Swann, D. G. Green. 2021-05-14. Positron cooling via inelastic collisions in CF$_4$ and N$_2$ gases. https://doi.org/10.1103/physrevlett.130.033001

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