Future X-ray Sources Will Enable New Science

Science and Technology of Future Light Sources (91 pages) by Argonne National Laboratory, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory and SLAC National Accelerator Laboratory

X-rays with energies above 10 keV offer capabilities extending beyond the nanoworld shown aboce due to their ability to penetrate into optically opaque or thick objects. This opens the door to combining atomic level information from scattering studies with 3D information on longer length scales from real space imaging with a resolution approaching 1 nm. The investigation of multiple length scales is important
in hierarchical structures, providing knowledge about function of living organisms, the atomistic origin of materials failure, the optimization of industrial synthesis, or the working of devices.

Future advanced x-ray sources and instrumentation will extend the power of x-ray methods to reach greater spatial resolution, increased sensitivity, and unexplored temporal domains. The purpose of this document is threefold:
1) summarize scientific opportunities that are beyond the reach of today’s x-ray sources and instrumentation;
2) summarize the requirements for advanced x-ray sources and instrumentation needed to realize these scientific opportunities, as well as potential methods of achieving them; and
3) outline the R&D required to establish the technical feasibility of these advanced x-ray sources and instrumentation.

Science Drivers

The need for advanced x-ray capabilities, two examples are given below of what we need to learn. They are related to “chemical reactivity” and “complex materials,”

• Knowing the importance of energy in guiding chemical reactions, we envision driving chemical transformations by controlled optical or infrared pulses and understanding the atomic and electronic transformation by means of advanced x-ray spectroscopies. More specifically, we need to capture, with snapshots on the femtosecond timescale, the making and breaking of chemical bonds and the crucial transition-state intermediates in chemical reactions.

• We foresee an understanding of the origins of nanoscale charge, spin, and orbital order and their dynamics in correlated materials through high-resolution energy- and time-dependent x-ray tools with nm resolution. The correlated interactions lead to unusual phenomena such as high-transition temperature superconductivity, metal-insulator transitions and novel phases. We need to visualize through ultrafast x-ray motion pictures the performance limits of materials and electronic devices, e.g., the speed limit of a spintronics device.

Time and Matter and Better Light Sources

Essential New X-Ray Capabilities
1 X-Ray Time Structure—Complete Control of Longitudinal Phase Space
2 Full Transverse Coherence
3 High Average Flux and Brightness
4 Tunability, Polarization Control, and Extended Photon Energies

Type of X-ray Sources with Enhanced Capabilities
1 Storage Rings
2 Energy Recovery Linacs (ERLs)
3 Linac-Based FELs [Free Electron Lasers]