Measurements of lifetimes of sodium Rydberg states in a cooled environment

Abstract

We have measured lifetimes of sodium $s$ and $d$ levels in the range $17<n<28$. Lifetime shortening due to blackbody radiation has been effectively eliminated by carrying out the measurements in a thermally isolated container cooled to 30 K. The individual lifetimes have been determined to 5% and agree well with calculations based on the Coulombic approximation. The validity of the calculation has been further tested using non-Coulombic methods. An ${({n}^{*})}^{3}$ scaling law has been obtained from the lifetimes and is accurate to 2.4%.