@article {8423,
	title = {Absolute Measurement of the Relativistic Magnetic Dipole Transition Energy in Heliumlike Argon},
	journal = {Physical Review Letters},
	volume = {109},
	year = {2012},
	note = {<p>PTDC/FIS/117606/2010 </p>
},
	month = {Jul},
	pages = {043005},
	abstract = {<p>The 1s2s 3S1 - 1s2 1S0 relativistic magnetic dipole transition in heliumlike argon, emitted by the plasma of an electron-cyclotron resonance ion source, has been measured using a double-flat crystal x-ray spectrometer. Such a spectrometer, used for the first time on a highly charged ion transition, provides absolute (reference-free) measurements in the x-ray domain. We find a transition energy of 3104.1605(77) eV (2.5 ppm accuracy). This value is the most accurate, reference-free measurement done for such a transition and is in good agreement with recent QED predictions.</p>
},
	url = {http://link.aps.org/doi/10.1103/PhysRevLett.109.043005},
	author = {Amaro, Pedro and Schlesser, Sophie and Guerra, Mauro and Le Bigot, Eric-Olivier and Isac, Jean-Michel and Travers, Pascal and Santos, Jose Paulo and Szabo, Csilla and Gumberidze, Alexandre and Indelicato, Paul}
}
