Spectral line shape in collinear laser spectroscopy after atomic charge exchange

Collinear laser spectroscopy (CLS) experiments on fast, neutral beams [1] have been extensively used for studies on short-lived radioactive nuclei, taking advantage of its high sensitivity, to deduce their radii and electromagnetic moments. For example, the recent CLS experiment on ²²Al to investigate possible proton halo structure was conducted on a neutral Al beam. The resulting resonance line shape is known to show significant distortion due to the energy exchange during the atomic charge-exchange neutralization process. Analysis of the distorted profiles can cause large systematic uncertainty in the determined centroid, from which the nuclear structure information is extracted. A model for the line shape was constructed and simulated to understand the cause of distortion and help design laser spectroscopy experiments on neutral beams. The model additionally removes the dependence on phenomenological shape parameters in the regression analysis. Details of the model, simulations, and application to experimental data on Al, Si, and Ni hyperfine spectra will be discussed.



[1] C. Ryder et al., Spectrochimica Acta Part B 113, 16 (2015).