Abstract
Ion beam analysis plays an important role in cultural heritage (CH) studies as it offers a combination of simultaneous and complementary analytical techniques (PIXE/PIGE/RBS) and spatially resolved mapping functions. Despite being considered non-destructive, the potential risk of beam-induced modifications during analysis is increasingly discussed. This work focuses on the impact of proton beams on parchment, present in our CH in form of unique historical manuscripts. Parchment is one of the organic, protein-based CH materials believed to be the most susceptible to radiation-induced changes. Various modification patterns, observed on parchment cross-sections by optical and electron microscopy are reported: discoloration (yellowing), formation of cavities and denaturation of collagen fibers. Considerable modifications were detected up to 100 µm deep into the sample for beam fluences of 4 µC/cm2 and higher. The presence of ultramarine paint on the parchment surface appears to increase the harmful effects of proton radiation. Based on our results, a maximum radiation dose of 0.5 µC/cm2 can be considered as ‘safe boundary’ for 2.3 MeV PIXE analysis of parchment under the applied conditions.
Highlights
Ion beam analysis plays an important role in cultural heritage (CH) studies as it offers a combination of simultaneous and complementary analytical techniques (PIXE/PIGE/RBS) and spatially resolved mapping functions
A total of eight parchment cross-sections were examined with OM and environmental scanning electron microscope (ESEM)
The in-detail examination by OM and ESEM of irradiated parchment samples highlighted considerable modifications for proton beam fluences of 4 and 10 μC/cm[2], and slight changes for lower collected charges (1 μC/ cm2) when the parchment has been covered with an ultramarine paint layer
Summary
Ion beam analysis plays an important role in cultural heritage (CH) studies as it offers a combination of simultaneous and complementary analytical techniques (PIXE/PIGE/RBS) and spatially resolved mapping functions. IBA facilities have progressively adapted to the requirements of unique and often fragile art and archaeological objects and provide nowadays a routine combination of simultaneous and complementary techniques (PIXE/PIGE/RBS), and mapping capabilities with micrometric spatial r esolution[15,16,17,18]. They can be ENSCP, Institut de Recherche de Chimie Paris – Centre de Recherche et de Restauration des Musées de France, UMR 8247 CNRS/MC, 14 quai François Mitterrand, 75001 Paris, France. The knowledge gained about the impact of proton beams can help establish guidelines for safe PIXE analysis on unique and fragile objects such as historical manuscripts
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