Observation of X-ray and Auger electron spectra in a 4π proportional counter for 4π(e, X)-γ coincidence measurements

Abstract

For the standardization of electron capture nuclides followed by γ-transitions, the 4π(e, X)-γ coincidence counting method is mainly adopted. To examine how the spectra of the (e, X) channel change with gas nature and pressure, pulse-height spectrum measurements of signals from a 4π pressurized proportional counter were carried out under various conditions for (54)Mn and (88)Y sources together with 4π(e, X)-γ coincidence counting. The spectra were measured for each half of the counter and for the combined 4π signal. The nature of counting gas (P-10 or methane) and its pressure was reflected in the X-ray peak intensity, and the Auger electron spectra were influenced significantly by the absorption in a thin VYNS film and the source conditions. In the measurements, we employed a pill-box type 4π counter in which the anodes were very thin gold-coated tungsten wires (30 μm ∅). In this system, spectra down to 0. 2 keV were clearly seen. The gas pressure can be raised up to 0.6 MPa. Counting electronics used for 4π(e, X)-γ coincidence measurements were conventional modules and a list mode two-parameter data acquisition system.

Keywords: 4π proportional counter; 4π(e, X)–γ coincidence counting; Auger electrons; Electron capture; Pulse-height spectrum; X-rays.