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The Next Generation of Current Measurement for Ionization Chambers



Ryan P. Fitzgerald, Denis E. Bergeron, Dean G. Jarrett, Neil M. Zimmerman, Carine Michotte, Hansjoerg Scherer, Stephen Giblin, Steven Judge


Re-entrant ionization chambers (ICs) are essential to radionuclide metrology and nuclear medicine for maintaining standards and measuring half-lives. Metrology-quality systems must be precise and stable to 0.1% over many years, and linear from 10^(-14) A to 10^(-8) A. Thus, labs depend on bespoke current measurement systems and often rely on sealed sources to generate reference currents. To maintain and improve present capabilities, metrologists need to overcome two looming challenges: ageing electronics and decreasing availability of sealed sources. Possible solutions using Ultrastable Low-Noise Current Amplifiers (ULCAs), resistive-feedback electrometers, and (quantum) single-electron pumps are reviewed. Broader discussions of IC design and methodology are discussed. ULCAs show promise and resistive-feedback systems which take advantage of standard resistor calibrations offer an alternative.
Applied Radiation and Isotopes


Ionization chambers, current measurement, small currents, gamma-ray


Fitzgerald, R. , Bergeron, D. , Jarrett, D. , Zimmerman, N. , Michotte, C. , Scherer, H. , Giblin, S. and Judge, S. (2020), The Next Generation of Current Measurement for Ionization Chambers, Applied Radiation and Isotopes, [online],, (Accessed June 19, 2024)


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Created August 31, 2020, Updated January 4, 2022