Low energy x-ray spectrometer for an electron beam ion trap

A flat-crystal spectrometer for analyzing ultrasoft x rays in the wavelength region 10–25 Å was constructed for use on an electron beam ion trap. The spectrometer employs a position-sensitive proportional counter for detection and affords a nominal resolving power of 2000 at a Bragg angle of 45°. Measurements of the L-shell spectra of Ne-like Fe16+ and of the 3s1/2–3p3/2 transitions in near Na-like Pb71+, which fall into the wavelength region from 13.5 to 17.5 Å, are presented demonstrating high throughput and excellent signal-to-noise characteristics. The actual resolving power achieved was limited by the intrinsic resolution of the crystal to 500. A resolving power close to the nominal value was achieved in second order Bragg reflection.