Characterization of thin layers with negative muons.
Cataldo M., Hillier A.D., Ishida K., Grazzi F., Porcinai S., Cremonesi O., Clemenza M.
Muonic X-ray Emission Spectroscopy ($\mu$XES) is a novel technique in the broad field of non-destructive methods for cultural heritage analysis. It relies on the interaction of a probe of negative muons with matter and the following emission of X-ray radiation. Since the muon mass is about 200 times bigger than the electron, the emitted X-rays are highly energetic and are characteristic of the emitting atom, making it possible to cover a wide part of the periodic table (from lithium to uranium). Thanks to the multi-elemental range, a negligible self-absorption effect of the X-rays and very low residual activity left in the sample after irradiation, $\mu$XES is a very powerful probe for material characterization, especially for archaeological findings. In this contribution, preliminary results of the analysis on two gilded surfaces are reported. Here, the data analysis is coupled with the results from Monte Carlo simulations for assessing the thickness of the different layers of the samples. Monte Carlo simulations, indeed, represent an invaluable tool for this particular technique since they can help in developing the data analysis, especially for thin layer characterization.