SPring-8 twin helical undulator

Abstract

There are several ways of producing circularly polarized light, such as using asymmetric devices, crossed undulators etc. The SPring-8 helical undulator introduces a simple way of producing both horizontal and vertical ®elds in one undulator. All the magnet arrays are arranged above and below the plane of the electron orbit, so there is no limitation of access from the sides of the undulator. For the SPring-8 BL25SU, two helical undulators will be installed in tandem, and the helicity of the polarization can be switched at up to 10 Hz using ®ve kicker magnets.

Measurement of Magnetic Exchange in Ferromagnet-SuperconductorLa2/3Ca1/3MnO3/YBa2Giblin1, Taylor2, Duffy3 et al. 2012Phys. Rev. Lett.16373View full textAdd to dashboardCite

“…were investigated with YBCO thicknesses of 2,4,5,6,7,8,11,15,16,20,22,25,26 and 30 u.c.. The samples were characterized using X-ray reflectivity to confirm the structural integrity and the change of thickness expected from the growth conditions, and magnetization measurements were performed using a commercial Quantum Design MPMS XL SQUID magnetometer.…”

“…To compensate for any beam instability, the XMCD measurements were performed using a doubledifference technique. The helicity of the light was reversed at 1Hz [15] whilst varying the incident energy under a particular fixed external magnetic field, immediately followed by an identical measurement performed with the externally applied magnetic field in the opposite direction. With the photon helicity and magnetization parallel (I + ) and antiparallel (I − ), information can be obtained about both the electronic structure (I + + I − ) and the magnetic properties (I + − I − ).…”

Project to renew the undulators at the photon factory

“…U#02-2 and U#28 are EPUs with six variable rows of magnetic arrays. They have the same magnetic arrangement as the SPring-8 helical undulator [6]. By adopting of this type EPU, the transverse uniformity of the magnetic field is better and the dynamic integrals along the electron orbit are smaller than the APPLE-II type EPU, especially in the case of EPU with the long period length.…”

Upgrade of beamline BL25SU for soft x-ray imaging and spectroscopy of solid using nano- and micro-focused beams at SPring-8

“…The soft X-ray beamline BL25SU (soft X-ray spectroscopy of solid) with a twin helical undulator source [1] was constructed in 1998 and was one of the first beamlines at SPring-8 [2]. This beamline has been used to study high energy resolution soft X-ray photoemission spectroscopy (PES), absorption spectroscopy, and soft X-ray magnetic circular dichroism (XMCD) of solid state materials.…”