Eiken Nakamura

Constant deviation monochromator for the range 100 Å≤λ≤1000 Å

A grazing incidence constant deviation monochromator with a spherical concave grating was fabricated for use with undulator radiation. It has a simple scanning mechanism with fixed entrance and exit slits, as well as fixed directions of incident and exit beams. It has been installed into an undulator beamline at IMS. Synchrotron radiation from a bending section also can be introduced into the monochromator by using premirrors. The energy resolution of the monochromator is better than 70 meV at the photon energy of 94 eV with 10‐μm slits, when the bending magnet synchrotron radiation is used. The spot size of the zeroth‐order light is 1.5(v)×2.0(h) mm2 at the distance of 1.85 m behind a postmirror. The photon flux of the undulator radiation behind the exit slit is approximately 1×1012 photons/s at the peak, when both the entrance and exit slits are 100 μm (ΔE=0.08 eV) and the stored current is 50 mA.

CONSTRUCTION OF CONSTANT-+DEVIATION CONSTANT-LENGTH SPHERICAL GRATING MONOCHROMATOR AT UVSOR

A constant‐deviation constant‐length spherical grating monochromator was constructed at the bending‐magnet beamline 8B1 of the UVSOR. The monochromator has a simple scanning mechanism with a fixed position of the entrance and exit slits, as well as fixed directions of incident and exit photon beams. The monochromator was designed to cover the photon energy of 31–620 eV with three interchangeable laminar gratings (1080 lines/mm: R=15 m, 540 lines/mm: R=15 m, 360 lines/mm: R=7.5 m). All gratings are original gratings fabricated on synthetic quartz substrates and coated with Au. The resolving power evaluated by ray tracing at the lowest energy of each grating with 10 μm slit width is ∼4400 for two high energy gratings and ∼7000 for a low energy grating. In the preliminary performance check, it was found that the output spectrum of the monochromator with G1 grating extends up to 870 eV with resolving power of ∼4000 at 400 eV with 10 μm slits.

SAMRAI: A novel variably polarized angle-resolved photoemission beamline in the VUV region at UVSOR-II

A novel variably polarized angle-resolved photoemission spectroscopy beamline in the vacuum-ultraviolet (VUV) region has been installed at the UVSOR-II 750 MeV synchrotron light source. The beamline is equipped with a 3 m long APPLE-II type undulator with horizontally/vertically linear and right/left circular polarizations, a 10 m Wadsworth type monochromator covering a photon energy range of 6-43 eV, and a 200 mm radius hemispherical photoelectron analyzer with an electron lens of a +/-18 degrees acceptance angle. Due to the low emittance of the UVSOR-II storage ring, the light source is regarded as an entrance slit, and the undulator light is directly led to a grating by two plane mirrors in the monochromator while maintaining a balance between high-energy resolution and high photon flux. The energy resolving power (hnu/Deltahnu) and photon flux of the monochromator are typically 1 x 10(4) and 10(12) photons/s, respectively, with a 100 microm exit slit. The beamline is used for angle-resolved photoemission spectroscopy with an energy resolution of a few meV covering the UV-to-VUV energy range.

Far-infrared spectroscopy by synchrotron radiation at the UVSOR Facility

At the UVSOR Facility, Institute for Molecular Science, the practical use of the synchrotron radiation as a far-infrared light source has started. A spectroscopic system has been constructed at the beam line BL6A1 of UVSOR storage ring, which covers the wavenumber region from 5 to 250 cm−1. The cross sectional diameter of the light beam at the sample position is as small as 3 mm with the angular divergence of about 100 mrad. The system has been made mainly for the transmission and reflection measurements of small samples with small angular divergence by the use of the high brightness of the synchrotron radiation. Examples of observed transmission and reflectivity spectra are shown.

BL5U at UVSOR‐II for Three‐dimensional Angle‐resolved Photoemission Spectroscopy

BL5U at UVSOR‐II has been reconstructed in 2004’s for three‐dimensional angle‐resolved photoemission (3D‐ARPES) study on solids and surfaces. The beamline is equipped with a helically/linearly polarized undulator, an old‐type monochromator named as SGM‐TRAIN designed in 1995’s, and a new photoemission end‐station. Since their performances are insufficient to study anomalous electronic/magnetic properties on materials in recent years, we reconstructed the beamline for a high‐resolution study as follows; (1) The manipulation of the pre‐focusing mirror was updated to a high‐precision system controlled by pulse‐motors. (2) The entrance slit with water cooling system was adopted for avoiding the heat load from undulator radiation. (3) The SGM‐TRAIN was re‐arranged to the optimum condition to the undulator light. (4) The free tuning program of the undulator gap and monochromator‐control systems was introduced. Due to the reconstructions, we successfully improved the throughput intensity and energy resolution of...

Design and performance of a new VIS–VUV photoluminescence beamline at UVSOR-III

A new bending-magnet beamline with a 2.5 m normal-incidence monochromator mainly dedicated to photoluminescence measurements of solids has been constructed at the UVSOR-III.

Construction and commissioning of a superconducting wiggler for the UVSOR storage ring

Abstract A 4-T superconducting wiggler of the wavelength-shifter type has been constructed and commissioned for experiments in the photon energy region above 2 keV at the 750-MeV UVSOR storage ring. It has a semi-closed liquefying system with two refrigerators that can confine liquid helium without loss. It has been confirmed that the wiggler can continuously run for one year without trouble. A feasibility study on low magnetic field operation of the wiggler was conducted for experiments with the lower photon energies below 2 keV using a double crystal monochromator with beryl crystals.

2.2‐m Rowland‐circle grazing‐incidence monochromator

A 2.2‐m Rowland‐circle grazing‐incidence monochromator with a fixed entrance slit and a fixed grating, has been installed on the beamline BL8B1 at UVSOR, in which the axis of the monochromatized beam is unchanged for the wavelength scanning. Two gratings are interchangeable in vacuum. The designed useful region is 20–200 A with a 2400/mm grating, but the actual useful region was 50–200 A. At 100 A, 1010/s output photons were obtained with a resolution of 10−3. The horizontal width of the beam at the sample position was about 5 mm, while the vertical width was between 0.5 and 3 mm.

Design of a High Resolution and High Flux Beam line for VUV Angle‐Resolved Photoemission at UVSOR‐II

A high‐energy‐resolution angle‐resolved photoemission beamline in the vacuum‐ultraviolet (VUV) region has been designed for a 750 MeV synchrotron light source UVSOR‐II. The beamline equips an APPLE‐II‐type undulator with the horizontally/vertically linear and right/left circular polarizations, a modified Wadsworth‐type monochromator and a high‐resolution photoelectron analyzer. The monochromator covers the photon energy range of 6 – 40 eV. The energy resolution (hv/Δhv) and the photon flux on samples are expected to be 2 × 104 and 1012 photons/sec at 10 eV, 4 × 104 and 5 × 1011 photons/sec at 20 eV, and 6 × 104 and 1011 photons/sec at 40 eV, respectively. The beamline provides the high‐resolution angle‐resolved photoemission spectroscopy less than 1 meV in the whole VUV energy range.

Design of a dedicated beamline for THz coherent synchrotron radiation at UVSOR-III

We report the design of a THz beamline for coherent synchrotron radiation (CSR) at the UVSOR-III very-low-emittance synchrotron radiation light source. The emitted THz-CSR is collected by a three-dimensional magic mirror, which is a perfect collecting mirror for bending-magnet radiation with an acceptance angle of 288 mrad (H) × 80 mrad (V). A quasi-monochromatic THz-CSR with an average flux of 104 μW/0.1 % b.w. and a peak power of 120 nJ/pulse/0.1 % b.w. is expected at the beamline.