A New Method for Dead Time Calibration and a New Expression for Correction of WDS Intensities for Microanalysis.

Autor:	Donovan JJ; CAMCOR, University of Oregon, 1443 East 13th Ave, Eugene, OR 97403, USA., Moy A; Geoscience Department, University of Wisconsin-Madison, 1215 W Dayton St, Madison, WI 53706, USA., von der Handt A; EOAS, University of British Columbia, 2207 Main Mall #2020, Vancouver, BC V6T 1Z4, Canada., Gainsforth Z; Space Sciences Laboratory, University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720, USA., Maner JL; Nuclear Materials Science Group, Materials Science and Technologist Division, Los Alamos National Laboratory, PO BOX 1663, Los Alamos, NM 87545, USA., Nachlas W; Geoscience Department, University of Wisconsin-Madison, 1215 W Dayton St, Madison, WI 53706, USA., Fournelle J; Geoscience Department, University of Wisconsin-Madison, 1215 W Dayton St, Madison, WI 53706, USA.
Jazyk:	angličtina
Zdroj:	Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada [Microsc Microanal] 2023 Jun 09; Vol. 29 (3), pp. 1096-1110.
DOI:	10.1093/micmic/ozad050
Abstrakt:	Observed photon count rates must be corrected for detector dead time effects for accurate quantification, especially at high count rates. We present the "constant k-ratio" method, a new approach for calibrating dead time for wavelength dispersive spectrometers by measuring k-ratios as a function of beam current. The method is based on the observation that for a given emission line at a specific take-off angle and electron beam energy, the intensity ratio from two materials containing the element should remain constant as a function of beam current, if the dead time calibration is accurate. The method has the advantage that it does not rely on the linearity of the beam current picoammeter, yet also allows the analyst to evaluate the picoammeter linearity, another critical parameter in EPMA calibration. By simultaneously comparing k-ratios for all spectrometers, one can also ascertain k-ratio consensus, essential for inter-laboratory comparisons. We also introduce improved dead time expressions and provide best practices on how to perform these instrument calibrations using this new "constant k-ratio" method. These improvements enable quantitative analysis of major and minor elements with high accuracy at high beam currents, simultaneously with trace elements with high sensitivity, for point analyses and X-ray mapping. Competing Interests: Conflict of Interest John Donovan is the president of Probe Software which offers automation and analysis software for EPMA instruments. (© The Author(s) 2023. Published by Oxford University Press on behalf of the Microscopy Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
Databáze:	MEDLINE
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