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

该主要研究仪器（MRI）合同将允许购买先进的x射线探测器EIGER2 S CdTe 9M，该探测器位于美国能源部科学办公室位于阿贡国家实验室（芝加哥，伊利诺伊州）的先进光子源第13区。这种探测器的升级将有助于克服在极端压力-温度条件下原位确定材料结构和组成的挑战，这在试图解决地球和行星科学中的许多基本问题时是有限的。这次升级所带来的新能力将促进新的实验，这些实验将解决地球和行星材料（如矿物、熔体和铁合金）物理和化学特性的关键方面，从而大大提高我们对行星内部结构和动力学的理解。拟议的收购将大大加强13区正在进行的前沿高压研究。升级后的APS-U同步加速器光束的质量将大大提高，光束聚焦更加紧密，亮度更高，相干性更高。这台新探测器的收购将充分利用此次升级，并将在XRD质量方面提供巨大而关键的改进。与目前使用的PILATUS探测器相比，DECTRIS的混合像素EIGER2 CdTe探测器具有显著的技术优势，具有更高的空间分辨率、更大的动态范围和更快的高能量帧速率。这些技术改进将提供新的能力，通过空间解析靠近位置的反射，更精确地确定XRD反射的形状和位置。该探测器将允许在长时间采集中明确检测弱反射，并将它们与更强的伪反射区分开来，从而实现许多以前无法实现的应用。这些改进对于单晶（SC） XRD和粉末XRD的全剖面细化至关重要，这可以在极端P-T条件下原位确定材料的结构和组成。这对于将高质量和高分辨率的XRD研究的P-T范围扩展到接近1 TPa的压力和接近10 kK的温度也是至关重要的，在这些条件下，样品非常小。升级后的XRD设备将能够对平衡相图（包括熔融）、相变动力学和动力学、低z材料的结构和组成以及非晶体材料的结构进行新的研究。新的研究将结合XRD测量与各种激光加热技术，动态压缩和DAC中样品的低温冷却。提出的激光加热系统与XRD相结合的主要技术改进将允许新的实验活动，通过对地球和行星材料（例如矿物，熔体和铁合金）的结构和物理特性的极大改进，来解决许多基本问题，极大地推进我们对行星内部结构和动力学的理解。现有的数据通常是相互矛盾的（例如，熔化和热/电输运性质），或者约束太弱，无法提供唯一的答案。这强调了在良好控制和校准的高P-T条件下，利用地幔和核类似物的原位测量来全面研究行星物质性质的必要性，例如这里提出的新探测器所实现的条件。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.