The gamma-ray radiography of decorative plasterwork

Abstract

AbstractThe technique of gamma-ray radiography has been used to obtain shadowgraphs of the internal metal framework (armatures) of several plaster and stucco figures. Both the technical and practical aspects of radiography of plasterwork have been considered, and while the gamma-ray sources 192Ir and 60Co may be particularly suited to very thin or thick subjects, respectively, a 137CS source of about one Curie is the most generally useful, and is capable of producing acceptable radiographs with stucco thicknesses up to about 50 to 60g/cm2. Laboratory tests using a 137Cs source showed that thickness sensitivities of 0·1cm of iron in 5·2g/cm2 of plaster, and 0·2cm of iron in a 32·5g/cm2 thickness of plaster, were attainable. It has also been found that wooden armatures (density about 0·7g/cm3) of diameter l·4cm can be detected in plaster of thickness 15·6g/cm2. Fieldwork has confirmed the results attained in the laboratory for wood and iron armatures; in addition features, such as cracks and density inhomog...