Speaker
Description
Pure crystals of CeBr3 material were initially produced by Schott Lithotec (Mainz) who then transferred production of several types of pure crystals to the enterprise Hellma Materials GmbH (Jena). CeBr3 is a scintillating material which is very suitable for photon spectrometry in the X-ray and gamma-ray range, in particular because of its high quantum yield. When properly coupled with a photomultiplier the resulting detector unit can serve for X-ray and gamma-ray spectrometry in successful competition with new high-resolution crystals like e.g. the proprietary material LaBr3:Ce which has a resolution (i.e. FWHM at 662 keV) of around 3%. The resolution of peaks in spectra measured with CeBr3 is typically around 4%. The somewhat poorer resolution of CeBr3, however, is well compensated by the fact that the detector is free of intrinsic radioactive material, like the natural abundance of 139La in lanthanum, and its 227Ac contamination is significantly smaller than in LaBr3:Ce.
Having apparent advantages of CeBr3 detectors in mind, spectral properties of the material were surveyed [1] and applicability of CeBr3 detectors for spectrometric applications was tested.
As most users of scintillation spectrometry have in the past worked with NaI(Tl) detectors, the comparisons are mostly focused on that material as a reference. Emphasis is laid onto the systematic display of properties of CeBr3 detectors, such as the full-energy peak efficiency function or the resolution function as function of photon energy, as these functions are relevant for quantitative peak analysis in measured spectra. To enable quantitative peak analysis the intrinsic peakshape of CeBr3 gamma-ray peaks was investigated and the resulting peakshape function was tested in analyses of spectra. For qualification of the CeBr3 material the internal contamination through 227Ac and its influence on the spectrum were experimentally determined.
Modern scintillation spectrometers often consist of a detector with PMT, plug-on multichannel analyzer and notebook PC which controls the unit and provides power to the MCA for over five hours of running time. Thus, portable scintillation spectrometry using a CeBr3 detector is well suitable for in-situ measurements such as for example:
- Environmental survey
- Survey and quantification in nuclear medicine
- Supervision in and around nuclear facilities
- Boarder transit controls
- Production water and scales in the oil and gas industry
- Prospecting
1) W. Westmeier and K. Siemon, “A Paradigm Shift in Nuclear Spectrum Analysis”, IEEE Transactions on Nuclear Science, Vol. 59/4 (2012), 1296
