Fast and versatile polarization control of X-ray by segmented cross undulator at SPring-8

Abstract

An X-ray is the well-known probe to examine structure of materials, including our own bodies. The X-ray beam, especially at the wavelength of nanometers, has also become significant to directly investigate electronic states of a sample. Such an X-ray is called a soft X-ray and polarization dependence of the light-matter interaction further unveils the microscopic properties, such as orbitals or spins of electrons. Generation of high brilliant beams of the polarized X-ray has linked to development of our experimental science, and it has been made by radiation from relativistic electrons at the synchrotron radiation facilities over the world. Recently, we constructed a new polarization-controlled X-ray source, the segmented cross undulator, at SPring-8, the largest synchrotron radiation facility in the world. The operation is based on interference of X-ray beams, which is sharply contrast to the conventional method of regulating electron trajectory by the mechanical control of magnets. The paradigm shift opened the measurement innovations and allowed us to design new experimental approaches to capture signals that have been hidden in materials. The present review describes the novel X-ray source with the principle of operation and the technical details of optimization. Examples of the frontier spectroscopies that use unique optical properties of the source are introduced, followed by the future prospects for next generation synchrotron radiation facilities.

Design of nano-spintronics beamline at 3-GeV next-generation synchrotron radiation facility, NanoTerasu

“…The side peak with higher energy at ∼720 eV has a high polarization (∼0.91) and thus this peak can be an useful alternative if one want higher polarization rather than the beam flux. These characteristics are consistent with the earlier reports [6,7].…”

“…To meet such criteria, we are constructing a new beamline 13U at NanoTerasu to provide photons in wide energy range from 180 to 3000 eV with small beam size and high flux (down to an order of 10 nm and above 10 11 photons/s, respectively). Moreover, a high-speed switching of arbitrary polarization, targeting down to 100 ms, will be realized by using a segmented undulator [5,6,7]; it would improve the efficiency of dichroism measurements significantly.…”

“…The interval between the centers of each undulator is 1.088 m. In these intervals, electromagnetic phase shifters are placed. They tune the interfere condition of photons from each undulator and thus control the polarization of the exit beam [5,6,7].…”

“…The interval between the centers of each undulator is 1.088 m. In these intervals, electromagnetic phase shifters are placed. They tune the interfere condition of photons from each undulator and thus control the polarization of the exit beam[5,6,7].Figure1(b) is the calculated photon flux entering the beamline. In this proceedings, we simulate the properties of the photons from the segmented undulator by using the software SPECTRA (ver.…”

Double-pulsed wave packets in spontaneous radiation from a tandem undulator

“…A tandem undulator, which consists of two undulators placed in series, is a powerful light source, bringing unique abilities—for example, polarization switching 2 – 4 and combination of different wavelength regimes 5 , 6 – in spectroscopic studies of matter. Moreover, interference between the radiation from the two undulators can be controlled by a phase shifter magnet which delays the electron motion, and is used to control the polarization of light in the crossed undulator scheme 7 – 10 and to verify the generation of structured light such as vortex beams 11 – 13 and vector beams 14 in synchrotron light sources. The waveform of each wave packet constituting the radiation has a double-pulsed time structure, reflecting the sequential undulating motion of electrons traveling through the tandem undulator.…”