Detection of faint X-ray spectral features using wavelength, energy, and spatial discrimination techniques

We report here our methods and results of measurements of very low-signal X-ray spectra produced by highly charged ions in an electron beam ion trap (EBIT). A megapixel Si charge-coupled device (CCD) camera was used in a direct-detection, single-photon-counting mode to image spectra with a cylindrically bent Ge(2 2 0) crystal spectrometer. The resulting wavelength-dispersed spectra were then processed using several intrinsic features of CCD images and image-analysis techniques. We demonstrate the ability to clearly detect very faint spectral features that are on the order of the noise due to cosmic-ray background signatures in our images. These techniques remove extraneous signal due to muon tracks and other sources, and are coupled with the spectrometer wavelength dispersion and atomic-structure calculations of hydrogen-like Ti to identify the energy of a faint line that was not in evidence before applying the methods outlined here.