Negative muons for the characterization of thin layers in Cultural Heritage artefacts

Muonic atom X-ray Emission Spectroscopy (mu- XES) is a novel technique based on the detection of high-energy X-rays emitted after the interaction of a negative muon beam with matter. Thanks to the multi-elemental range, negligible self-absorption of the x-rays and the possibility of performing depth profile studies, the technique is a very powerful probe for the analysis of cultural heritage artefacts. By tuning the energy of the incident muon beam, indeed, it is possible to investigate the different layers that constitute a sample. In this work, we report preliminary results of the analysis on two fire-gilded surfaces, in which the data analysis is coupled with Monte Carlo-based simulation software. Here, to perform a depth profile characterization, the samples were analysed at different beam energies (or momentum). Each of the resulting x-ray spectra was then analysed and compared with the output of the simulations software and a remarkably good agreement was reached. The results of the work are promising and with this approach, it will be possible to enhance the capability offered by the technique, both in terms of data analysis and data interpretation.