Specific Synchrotron Radiation Facilities Users Community (SpRUC)

Compton scattering is an experimental technique for measuring spin-specific electron momentum distribution. These measurements are available by using monochromatic, high-energy, high-flux, and circularly polarized X-rays, which is a strength of SPring-8 in the world. Compton scattering has the following unique advantage over other experimental techniques.

• Compton scattering can measure the quantum states of the ground state in a wide momentum space, providing information about the bulk electronic structure, enabling us to directly compare with the results of first-principle calculations.
• Compton scattering can measure spin-specific quantum states using circularly polarized X-rays. Moreover, the majority and minority spin states can be obtained.
• Compton scattering can enable us to measure under extreme and combined conditions like high (low) temperature, high pressure, and magnetic fields by the high penetration property of high-energy X-rays.
• Compton scattering can be applied as a new non-destructive and operando imaging technique, which includes the information of quantum state using high transmittance of high-energy X-rays.

These features of Compton scattering generate very unique activities in the world. Also, we carry out the following activity for the next plan of the SPring-8.

1. We develop a new measurement technique by using Compton scattering and high transmittance of high-energy X-rays.
   　i). We develop new non-destructive testing by using Compton scattering and high transmittance of high-energy X-rays(Ex, Operando measurements of electrochemical reaction distribution in a Li ion battery).
   　　 ii). We develop new measurement techniques, such as magnetic imaging using magnetic Compton scattering.
2. We carry out basic research on quantum states in momentum space, which concerns the function of materials, and collaborate with the theory group.
   　i). Imaging of quantum states: Visualization of the Fermi surface, spin/orbital states of strongly correlated materials, high Tc materials, electrochemical reaction, and so on.
   　　 ii). Extreme condition: Supercritical states, high-energy-density materials, non-equilibrium materials.
3. New measurement technique for the next SPring-8 plan.
   　i). Data analysis using informatics.
   　　 ii). 2D detector with energy discrimination for imaging.
   iii). High momentum resolution measurement.
   　 　iv). Devices for circularly polarized X-rays.
   

The renewal of experimental instruments will be considered because the present instruments are deteriorating. We promote the progress of science and social challenges by collaborating with researchers. Furthermore, we suggest the next plan for SPring-8II.