MRI: Acquisition of an advanced X-ray detector for static and dynamic synchrotron X-ray scattering studies of materials at extreme conditions at the Advanced Photon Source

This Major Research Instrumentation (MRI) award will permit the purchase of an advanced X-ray detector, EIGER2 S CdTe 9M at Sector 13 of the Advanced Photon Source, a U.S. Department of Energy Office of Science user facility at Argonne National Laboratory (Chicago, IL). This detector upgrade will help to overcome the challenges in determining the structure and composition of materials in-situ at extreme pressure-temperature conditions, which are currently limited when trying to resolve many fundamental questions in Earth and planetary sciences. New capabilities enabled by this upgrade will facilitate novel experiments which will address key aspects of physical and chemical properties of Earth and planetary materials such as minerals, melts, and iron alloys, thus greatly advancing our understanding of planetary interior structure and dynamics. The proposed acquisition will significantly enhance frontier high pressure research being conducted at Sector 13. The quality of the synchrotron beam at the upgraded APS-U will be greatly improved, with a more tightly focused, brighter, and highly coherent beam. Acquisition of this new detector will take full advantage of the upgrade and will provide a vast and critical improvement in the quality of XRD. The hybrid-pixel EIGER2 CdTe detector from DECTRIS has significant technical advantages versus the currently used PILATUS detector with higher spatial resolution, larger dynamic range, and faster frame rates at high energies. These technical improvements will provide new abilities to determine XRD reflection shapes and positions much more precisely by spatially resolving closely positioned reflections. The detector will allow definitive detection of weak reflections in long acquisitions and discriminate them from much stronger spurious reflections, thus enabling numerous previously unrealizable applications. These improvements are most critical for single-crystal (SC) XRD and full profile refinement of powder XRD, which can determine the structure and composition of materials in situ at extreme P-T conditions. It is also critical for extending the P-T range of high-quality and high-resolution XRD studies to pressures approaching 1 TPa and temperatures approaching 10 kK, where samples are exceptionally small. An upgraded XRD facility will enable new investigations of equilibrium phase diagrams (including melting), phase transition kinetics and dynamics, the structure and composition of low-Z materials, and the structure of non-crystalline materials. New investigations will combine XRD measurements with a variety of laser heating techniques, dynamic compression, and cryogenic cooling of samples in the DAC. The proposed major technological improvements of the laser heating system combined with XRD will allow new experimental campaigns for addressing many fundamental questions through a much-improved capability to interrogate the structure and physical properties of Earth and planetary materials (e.g., minerals, melts, and iron alloys), greatly advancing our understanding of planetary interior structure and dynamics. Existing data are often contradictory (e.g., melting and thermal/ electrical transport properties) or too poorly constrained to provide unique answers. This underscores the need for comprehensive investigations of the properties of planetary material using in situ measurements on mantle and core analogues in well controlled and calibrated high P-T conditions, such as those made possible by the new detector proposed here. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.