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Methoden und Instrumentierung Poster: Mi., 14:00–16:30 M-P54
Electron Emission channeling spectrometer using X-ray CCD detectors
Velimir Milinovic 1 , Carsten Ronning 1 , Hans Hofsäss 1
1 II. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077
Göttingen
We present a new spectrometer developed for electron emission channeling studies at
the ISOLDE isotope spearator facility at CERN using an energy- and position sensitive
CCD detector originally developed for imaging of soft X-rays in X-ray astronomy
telescopes [1].
The lattice sites of impurity atoms in crystalline materials can be determined with
high precision and high sensitivity using the emission channeling technique [2]. This
spectroscopic method provides valuable information on the structure, the diffusion behavior
and the defect interaction of impurity atoms in crystalline solids. In the
emission channelingC technique, radioactive impurity atoms are ion implanted and
the emission distribution of decay particles around different crystallographic directions
are measured. Isotopes emitting conversion electrons with well-defined energies in the
range of several 10 keV up to several 100 keV are particular well-suited for such studies,
because such electrons exhibit pronounced channeling effects (enhanced emission intensity)
along crystallographic axes and planes if the emitter atoms are located within
the respective atom rows and planes. The measurement of electron channeling spectra
requires the energy- and angle-resolved detection of conversion electrons with an
angular precision of typically 0.1 deg. Instead of using conventional semiconductor detectors,
the use of the CCD detector significantly improves the quality of the measured
emission distributions and will drastically reduce the acquisition time.
It is demonstrated that the X-ray CCD detector is an excellent detector for conversion
electrons with extremely low noise and an good energy resolution [3]. Possible
applications of the new spectrometer for electron channeling spectroscopy are outlined.
[1] L. Strueder, et al. Rev. Sci. Instrum. 68, 4271 (1997)
[2] H. Hofsäss, G. Lindner, Phys. Rep. 201, 121 (1991)
[3] H. Hofsäss, et al., Nucl. Instr. Meth. A 512 (2003) 378