# Spectral line-shape in collinear laser spectroscopy after atomic charge exchange

## TL;DR

This paper develops a model to accurately describe the distorted spectral line-shape in collinear laser spectroscopy caused by charge exchange, improving the precision of measurements on fast neutral atomic beams.

## Contribution

A new, physically motivated model for the spectral line-shape distortion in collinear laser spectroscopy after atomic charge exchange is introduced, reducing reliance on phenomenological fitting.

## Key findings

- The distortion is mainly due to electron transfer to multiple energy levels and subsequent decays.
- The model successfully fits measured hyperfine spectra of Al, Si, and Ni.
- It can be applied to various projectile-alkali pairs with fewer parameters.

## Abstract

Collinear laser spectroscopy experiments on fast, neutral beams have been extensively used for studies on short-lived radioactive nuclei, taking advantage of its high sensitivity. The resulting resonance line-shape is known to show significant distortion, due to the energy exchange during the charge-exchange neutralization process, which can cause large systematic uncertainty in the determined centroid. A model for the line shape was constructed and simulated to be compared to measured Al, Si, and Ni hyperfine spectra. It is shown that the distortion is caused mainly by the transfer of electron into many different energy levels in the projectile atom and subsequent decays, rather than secondary inelastic collisions, which were often assumed in the line shape analysis before. The model can also be applied to other projectile-alkali pairs, providing a reliable line-shape with less fitting parameters than conventional phenomenological models.