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

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 ${\nu }_1$ mode, in addition to the dipole-active modes ${\nu }_3$ and ${\nu }_4$, can provide room-temperature thermalization and an accurate cooling timescale. Combination cooling enabled by the ${\nu }_1$ 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.

6 pages, 7 figures

References in corpus (5)

• Positron-molecule interactions: resonant attachment, annihilation, and bound states
• Many-body theory of positron binding in polyatomic molecules
• Model-potential calculations of positron binding, scattering, and annihilation for atoms and small molecules, using a Gaussian basis
• Positron cooling and annihilation in noble gases
• Probing positron cooling in noble gases via annihilation $\gamma$ spectra

Cited by in corpus (1)

• Many-Body Theory Calculations of Positron Scattering and Annihilation in H${}_2$, N${}_2$ and CH${}_4$