The commercial availability of LaCl3:Ce scintillators has been much anticipated due to their significantly lower resolution relative to NaI(Tl). Our investigation of these scintillators in regards to the effect of their improved resolution for coincidence gamma-ray measurement applications revealed that the scintillators had a large, internal alpha contamination affecting the gamma-ray energy range from 1700-3000 keV. One passive method of identifying contaminants relies on exploiting coincident signatures. Aided by a coincidence lookup library developed at PNNL, we determined that the parent contaminant is Ac-227 via an alpha-gamma coincidence measurement. In this paper, we characterize the level of contamination and describe our coincidence measurement technique. The Ac-227 concentration was approximately 0.13 ppt. We demonstrate that this coincidence technique measures minimum detectable activities much lower than singles gamma-ray spectroscopy. We also discuss gamma- and beta-contamination in these scintillators.
Revised: August 10, 2011 |
Published: August 1, 2005
Citation
Milbrath B.D., R.C. Runkle, T.W. Hossbach, W.R. Kaye, E.A. Lepel, B.S. McDonald, and L.E. Smith. 2005.Characterization of Alpha Contamination in Lanthanum Trichloride Scintillators Using Coincidence Measurements.Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment 547, no. 2-3:504-510.PNNL-SA-42859.