We have measured resonance strengths and energies for dielectronic recombination ( DR ) of Mg-like Fe xv forming Al-like Fe xiv via N = 3 \to N ^ { \prime } = 3 core excitations in the electron-ion collision energy range 0–45Â eV .
All measurements were carried out using the heavy-ion Test Storage Ring at the Max Planck Institute for Nuclear Physics in Heidelberg , Germany .
We have also carried out new multiconfiguration Breit-Pauli ( MCBP ) calculations using the AUTOSTRUCTURE code .
For electron-ion collision energies \lesssim 25 Â eV we find poor agreement between our experimental and theoretical resonance energies and strengths .
From 25 to 42Â eV we find good agreement between the two for resonance energies .
But in this energy range the theoretical resonance strengths are \approx 31 \% larger than the experimental results .
This is larger than our estimated total experimental uncertainty in this energy range of \pm 26 % ( at a 90 \% confidence level ) .
Above 42Â eV the difference in the shape between the calculated and measured 3 s 3 p ( ^ { 1 } P _ { 1 } ) nl DR series limit we attribute partly to the nl dependence of the detection probabilities of high Rydberg states in the experiment .
We have used our measurements , supplemented by our AUTOSTRUCTURE calculations , to produce a Maxwellian-averaged 3 \to 3 DR rate coefficient for Fe xv forming Fe xiv .
The resulting rate coefficient is estimated to be accurate to better than \pm 29 \% ( at a 90 \% confidence level ) for k _ { B } T _ { e } \geq 1 Â eV .
At temperatures of k _ { B } T _ { e } \approx 2.5 - 15 Â eV , where Fe xv is predicted to form in photoionized plasmas , significant discrepancies are found between our experimentally-derived rate coefficient and previously published theoretical results .
Our new MCBP plasma rate coefficient is 19 - 28 \% smaller than our experimental results over this temperature range .