X-ray spectroscopy of highly charged ions: application of position sensitive germanium detectors

Segmented and position sensitive germanium detector systems play an important role for future X-ray spectroscopy experiments with highly charged heavy ions. The unique properties of such systems are millimeter to sub-millimeter spatial resolution as well as a good time and energy resolution for the hard X-ray regime above 15 keV. When dealing with fast moving heavy ions at accelerators or storage rings, this spatial resolution guarantees for a suppression of Doppler broadening without a loss of detection efficiency. Another example is the combination with a focusing crystal spectrometer, where a position-segmented detector permits the measurement of an energy spectrum wide enough to investigate the interesting energy regime simultaneously. In addition, good energy resolution enables discrimination against background events of the recorded spectra arising from various sources. Very recently such a micro-strip detector system, developed at the Forschungszentrum Julich, with a position resolution of close to 200 μm has become available An additional important feature of such detector systems is their sensitivity to the photon polarization at energies above 50 keV. By means of such detection devices, the polarization of atomic transitions in highly charged heavy ions can be addressed experimentally with high accuracy.