Standardization of a micro-PIXE system using NIST iron- and nickel-based alloy reference materials

Five NIST standard reference Mo-bearing alloys are evaluated in the context of standardizing a micro-PIXE system that operates with a range of aluminu m X-ray absorbers. The instrumental constant H is determined with accuracy of about 1% via the Mo content, and the absorber thickness is subsequently deduced via the Fe or Ni content. The influence of alloy heterogeneity is e xamined, and it is found necessary to raster the beam spot to compensate. T he steel SRM C1296 is our choice for characterization when the absorber thi ckness is 300 mu m or less. The Ni-based alloy SRM 1160 is suitable for abs orbers in the range 300-500 mu m. (C) 2000 Elsevier Science B.V. All rights reserved.