Effective collision strengths for allowed transitions among the n $\mathsf{\le}$ 5 degenerate levels of Al XIII

Abstract

Aims. In this paper we report on calculations of collision strengths and effective collision strengths for allowed transitions among the $n \le$ 5 degenerate levels of Al xiii. Methods. The Dirac atomic R -matrix code (darc) has been adopted for these calculations. Results. Collision strengths are reported over a wide energy range below 300 Ryd, and effective collision strengths are provided for electron temperatures of 4.4 ≤ log $T_{\rm e} \le$ 6.8 K.