Performance upgrade in the JAEA actinide sciencebeamline BL23SU at SPring-8 with anewtwin-helical undulator.

Yuji Saitoh,Toru Hara,Masao Takeuchi,Yoshihiro Asano,Takashi Tanaka,Sunao Takahashi,Yukiharu Takeda,Hideo Kitamura,Yoshihiro Fukuda,Hiroshi Yamagami,Katsutoshi Shirasawa

doi:10.1107/s0909049512006772

Abstract

The soft X-ray beamline BL23SU at SPring-8 has undergone an upgrade with a twin-helical undulator of in-vacuum type to enhance the experimental capabilities of the endstations. The new light source with a fast helicity-switching operation allows not only the data throughput but also the sensitivity in X-ray magnetic circular dichroism (XMCD) to be improved. The operational performance and potential are described by presenting XMCD results of paramagnetic β-US(2) measured with a 10 T superconducting magnet.

Highlights

The JAEA actinide science beamline, BL23SU, built and operated by Japan Atomic Energy Agency (JAEA), is a soft X-ray beamline at the SPring-8 synchrotron facility with its first light being received in 1998 (Saitoh et al, 2001)
The primary aim of BL23SU is to investigate the electronic structures of uranium-based compounds and related materials using soft X-ray photoemission (SX-PES) and magnetic circular dichroism (XMCD) spectroscopies with a focus on superconductivity and magnetism
The uranium compounds display a variety of intriguing phenomena, which is considered to be due to complex many-body interactions between the valence-electron states

Summary

Introduction

The JAEA actinide science beamline, BL23SU, built and operated by Japan Atomic Energy Agency (JAEA), is a soft X-ray beamline at the SPring-8 synchrotron facility with its first light being received in 1998 (Saitoh et al, 2001). A local feed-forward correction system for the orbit distortion at the switching time up to around 2.5 s between opposite helical polarizations (the phase parameter in its pure helical mode was roughly proportional to the gap) has been developed (Nakatani et al, 2005) This system allowed us to perform efficient XMCD measurements using a superconducting magnet under fixed sample conditions (Okamoto et al, 2004). The twin-helical undulator of ID23 can be applied to XMCD experiments at much higher switching frequency by using a fast mechanical chopper and angularly separated dual photon beams, in which the kicker magnets generate a stationary orbit bump (Sawhney et al, 1997). We report here its performance for XMCD experiments as well as some recent upgrades of BL23SU

Beamline description

Application to a uranium compound

Findings

Summary