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C U L T U R A L H E R I T A G E , A R C H A E O L O G Y A N D P A L A E O N T O L O G Y

The community of ESRF users working in the field of cultural and natural heritage is small (~1% of the total ESRF users) but steadily growing. The ESRF is increasingly recognised worldwide as a leading facility for the study of complex, valuable materials from cultural and natural heritage. As highlighted in this chapter, ESRF beamlines support diverse applications, including deciphering the manufacturing processes of artistic materials such as pigments, investigating degradation processes and conservation practices, and tracing the evolution of species through geological time. Since the Extremely Brilliant Source (EBS) began operation in 2020, several significant initiatives have further advanced these activities.

Advances in cultural heritage research

Since the ESRF-EBS user operation started, cultural heritage activity has been particularly strengthened through the implementation of the Historical Materials Block Allocation Group (BAG), which provides regular access to two beamlines: ID22 for high-angular- resolution X-ray powder diffraction (HR-XRPD) and ID13 for micro-XRPD mapping. The success of the BAG stems in part from the high throughput of these beamline configurations, which enable the scanning of a very large number of samples (>200) in just a few days. For instance, research on the composition of cobalt-based pigments in Robert Delaunay’s Autoportrait, highlighted on page 116, was carried out within the framework of the BAG at ID22. The combination of HR-XRPD

structural analysis with precise attribution of UV–vis– NIR spectra provided a unique correlation between ancient synthesis processes and the visual appearance of artworks. In addition, the analysis of the degradation of emerald pigment in James Ensor’s Intrigue, detailed on page 118, also benefitted from BAG access for micro- XRPD mapping at ID13. Phase maps complemented the X-ray absorption spectroscopy data obtained at BM23 and ID21 on arsenic and copper-based compounds, enabling researchers to track the nature and distribution of both original and degradation compounds.

Improving metadata and FAIR compliance

To further align with FAIR data principles, the ESRF is improving metadata collection, supported by the “OSCARS” project (Grant Agreement No. 101129751, under the European Commission’s Horizon Europe research and innovation programme). A web interface has recently been deployed to allow BAG users to provide structured information about their samples.

Tomography and natural heritage applications

While the cultural heritage community mostly uses spectroscopy and diffraction beamlines, the natural heritage community is more active on tomography beamlines at the ESRF. This reflects their respective priorities: cultural heritage focuses on understanding composition and chemistry, whereas natural heritage often requires complete assessment of specimen morphology, particularly in fossils. In this context, the beamlines ID19, BM05, and BM18 stand out worldwide for X-ray phase-contrast micro-computed tomography, notably due to the brilliance and high spatial coherence