# Transition rates and radiative lifetimes of Ca I

## TL;DR

This paper provides comprehensive ab initio calculations of spontaneous emission rates for all electric-dipole-allowed transitions among the lowest-energy states of neutral calcium, aiding various atomic physics applications.

## Contribution

It presents the first complete tabulation of transition rates for 811 transitions in Ca I using relativistic configuration interaction and many-body perturbation theory.

## Key findings

- Transition rates are consistent with existing literature where available.
- The data can improve laser cooling and optical clock accuracy.
- The results facilitate calculations of atomic polarizabilities and interaction coefficients.

## Abstract

We tabulate spontaneous emission rates for all possible 811 electric-dipole-allowed transitions between the 75 lowest-energy states of Ca I. These involve the $4sns$ ($n=4-8$), $4snp$ ($n=4-7$), $4snd$ ($n=3-6$), $4snf$ ($n=4-6$), $4p^2$, and $3d4p$ electronic configurations. We compile the transition rates by carrying out ab initio relativistic calculations using the combined method of configuration interaction and many-body perturbation theory. The results are compared to the available literature values. The tabulated rates can be useful in various applications, such as optimizing laser cooling in magneto-optical traps, estimating various systematic effects in optical clocks and evaluating static or dynamic polarizabilities and long-range atom-atom interaction coefficients and related atomic properties.