# Measurement of charge-exchange between Na and \ce{Ca+} in a hybrid trap

## TL;DR

This study measures charge-exchange reaction rates between neutral sodium and ionized calcium in a hybrid trap, revealing energy-dependent rates and thresholds for different electronic states, with most rates aligning with classical predictions.

## Contribution

The paper provides the first detailed measurements of state-resolved charge-exchange rates between Na and Ca+ in a hybrid trap, including energy thresholds for specific channels.

## Key findings

- Most reaction rates agree with Langevin predictions.
- Identified collision-energy thresholds for two reaction channels.
- Measured four individual reaction rates at different energies.

## Abstract

We present measurements of the charge-exchange reaction rate between neutral sodium (Na) and ionized calcium (\ce{Ca+}) in a hybrid atom-ion trap, which is comprised of a Na magneto-optical trap concentric with a linear Paul trap. Once the Na and \ce{Ca+} are co-trapped, the reaction rate is measured by continuously quenching the reaction product \ce{Na+} from the ion trap, and then destructively measuring the decay of the remaining ion population. The reactants' electronic state and temperature are experimentally controlled, allowing us to determine the four individual reaction-rates between $\text{Na}[\text{S~or~P}]$ and $\text{Ca}^+[\text{S~or~D}]$ at different collision energies. With the exception of the largest reaction-rate channel ($\text{Na}[\text{S}]+\text{Ca}^+[\text{D}]$), our rates agree with classical Langevin rate limit. We have also found evidence of reactant collision-energy thresholds associated with two of the four entrance-channels.