PIXE spectrometry as an archaeometric tool

Abstract

The first part of this paper describes the physical processes of PIXE that underlie its advantages as an analytical tool in the study of ancient artifacts, and the practical limitations met in the compositional patterning of bronzes, irons and glasses. Emphasis here is laid upon how a controlled variation of the proton beam's energy, and the use of selective filters in the detection system, allow certain background effects from the X-ray output of the dominant matrix element to be significantly reduced. The second part outlines current plans for the modification of the Bartol PIXE facility to provide a tightly-focused proton beam (typically 20 μm across) coupled to a laser-based optical system that will allow precise definition of the activated area of the artifact's surface. Such a configuration will much increase the range of applicability of the PIXE method, to encompass several inhomogeneous materials of archaeological interest, such as metal residues trapped in smelting slag, solder joins in Classical jewelry, and bronze (or iron) artifacts in which only islands of metal survive in a heavily developed matrix of corrosion products.