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Title: Status of the Twin Helical Undulator Soft X-ray Beamline at SPring-8: Performance for Circular Dichroism Measurements

Abstract

The status of the soft x-ray beamline BL25SU at SPring-8 is reported. The beamline performance for circular dichroism measurements using the helicity switching of helical undulator radiation is focused on. Light spots on a sample of the opposite helicities have been observed with a photoelectron emission microscope. The vertical profiles of the spots have almost the same line shape and a positional difference of {approx} 0.5 {mu}m. The horizontal spot positions coincide, but the horizontal spot widths are different by {approx} 7 %. The energy difference of the monochromatized light between the opposite helicities has been estimated to be less than or comparable to 1 meV in the Ne 1s absorption region. The kick angle of the kicker magnets has been increased from 0.2 to 0.3 mrad to avoid penetration of the higher harmonics.

Authors:
; ; ; ; ; ; ;  [1];  [2]; ;  [3];  [4];  [3]
  1. JASRI/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)
  2. Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-0082 (Japan)
  3. RIKEN/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)
  4. (Japan)
Publication Date:
OSTI Identifier:
21052581
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 879; Journal Issue: 1; Conference: 9. international conference on synchrotron radiation instrumentation, Daegu (Korea, Republic of), 28 May - 2 Jun 2006; Other Information: DOI: 10.1063/1.2436125; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ABSORPTION; BEAM PRODUCTION; DICHROISM; HARMONICS; HELICITY; KICKER MAGNETS; PERFORMANCE; PHOTON BEAMS; SOFT X RADIATION; SPRING-8 STORAGE RING; WIGGLER MAGNETS

Citation Formats

Muro, T., Nakamura, T., Matsushita, T., Fukumoto, K., Kimura, H., Hirono, T., Kinoshita, T., Takeuchi, M., Wakita, T., Hara, T., Kitamura, H., JASRI/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, and Shirasawa, K.. Status of the Twin Helical Undulator Soft X-ray Beamline at SPring-8: Performance for Circular Dichroism Measurements. United States: N. p., 2007. Web. doi:10.1063/1.2436125.
Muro, T., Nakamura, T., Matsushita, T., Fukumoto, K., Kimura, H., Hirono, T., Kinoshita, T., Takeuchi, M., Wakita, T., Hara, T., Kitamura, H., JASRI/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, & Shirasawa, K.. Status of the Twin Helical Undulator Soft X-ray Beamline at SPring-8: Performance for Circular Dichroism Measurements. United States. doi:10.1063/1.2436125.
Muro, T., Nakamura, T., Matsushita, T., Fukumoto, K., Kimura, H., Hirono, T., Kinoshita, T., Takeuchi, M., Wakita, T., Hara, T., Kitamura, H., JASRI/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, and Shirasawa, K.. Fri . "Status of the Twin Helical Undulator Soft X-ray Beamline at SPring-8: Performance for Circular Dichroism Measurements". United States. doi:10.1063/1.2436125.
@article{osti_21052581,
title = {Status of the Twin Helical Undulator Soft X-ray Beamline at SPring-8: Performance for Circular Dichroism Measurements},
author = {Muro, T. and Nakamura, T. and Matsushita, T. and Fukumoto, K. and Kimura, H. and Hirono, T. and Kinoshita, T. and Takeuchi, M. and Wakita, T. and Hara, T. and Kitamura, H. and JASRI/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 and Shirasawa, K.},
abstractNote = {The status of the soft x-ray beamline BL25SU at SPring-8 is reported. The beamline performance for circular dichroism measurements using the helicity switching of helical undulator radiation is focused on. Light spots on a sample of the opposite helicities have been observed with a photoelectron emission microscope. The vertical profiles of the spots have almost the same line shape and a positional difference of {approx} 0.5 {mu}m. The horizontal spot positions coincide, but the horizontal spot widths are different by {approx} 7 %. The energy difference of the monochromatized light between the opposite helicities has been estimated to be less than or comparable to 1 meV in the Ne 1s absorption region. The kick angle of the kicker magnets has been increased from 0.2 to 0.3 mrad to avoid penetration of the higher harmonics.},
doi = {10.1063/1.2436125},
journal = {AIP Conference Proceedings},
number = 1,
volume = 879,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2007},
month = {Fri Jan 19 00:00:00 EST 2007}
}
  • A measurement system for circular dichroism (CD) of soft X-ray absorption has been developed using helicity switching of circularly polarized radiation by twin helical undulators at BL25SU of SPring-8. Difference of horizontal spot positions between the negative- and positive-helicity light at the sample position is within {+-}3{mu}m. Measurement time for magnetic circular dichroism (MCD) of core absorption is shortened to less than 1/3 in comparison with an existing system of magnetic field switching, keeping the same data quality.
  • Refocusing mirrors were designed and equipped in the high-resolution branch of BL27SU in SPring-8. It is required to switch quickly among the three tandem end-stations and achieve a vertical size of less than 10 microns at one experimental station. Two toroidal mirrors and a set of two cylindrical mirrors were employed in order to align them easily. The beam size and photon flux were measured.
  • A new soft x-ray beamline BL17SU (RIKEN) has been constructed at SPring-8. The beamline consists of two branches with each varied-line-spacing-plane-grating-monochromator. Both monochromators perform high energy resolution (E/{delta}E > 10,000) between 0.2 and 1 keV. One of the monochromator achieves high energy stability of 10 meV over a period of half a day.
  • The soft x-ray beamline 5U1 on the Daresbury Laboratory SRS currently uses a planar undulator, producing linearly polarized radiation in the range 100 to 1000 eV. The undulator is soon to be replaced by a variable-polarization device of the Apple II design. The aim is to produce circularly polarized light in the energy range 265 to 1000 eV, covering the K-edges of C, N and O, and the first row transition element L-edges. This will greatly enhance the provision of circularly polarized soft-x-rays on the SRS and open up new opportunities for experimenters. The device will also produce linear polarizationmore » with a selectable angle of polarization with respect to the orbit plane, which is currently unavailable on the SRS. In order to provide the coverage over this energy range, we are exploiting the relatively large emittance of the SRS to allow us to use the second and third harmonics even in circular polarization mode. This paper presents the expected beamline output in various polarization modes and the predicted degree of polarization.« less
  • A femtosecond pulsed laser system has been installed at the BL25SU soft x-ray beamline at SPring-8 for time-resolved pump-probe experiments with synchronization of the laser pulses to the circularly polarized x-ray pulses. There are four different apparatuses situated at the beamline; for photoemission spectroscopy, two-dimensional display photoelectron diffraction, x-ray magnetic circular dichroism (XMCD) with electromagnetic coils, and photoelectron emission microscopy (PEEM). All four can be used for time-resolved experiments, and preliminary investigations have been carried out using the PEEM apparatus to observe magnetization dynamics in combination with XMCD. In this article, we describe the details of the stroboscopic pump-probe XMCD-PEEMmore » experiment, and present preliminary data. The repetition rate of the laser pulses is set using a pulse selector to match the single bunches of SPring-8's hybrid filling pattern, which consists of several single bunches and a continuous bunch train. Electrons ejected during the bunch train, which do not provide time-resolved signal, are eliminated by periodically reducing the channel plate voltage using a custom-built power supply. The pulsed laser is used to create 300 ps long magnetic field pulses, which cause magnetic excitations in micron-sized magnetic elements which contain magnetic vortex structures. The observed frequency of the motion is consistent with previously reported observations and simulations.« less