title: A dedicated small-angle X-ray scattering beamline with a superconducting wiggler source at the NSRRC.
abstract: At the National Synchrotron Radiation Research Center (NSRRC), which operates a 1.5 GeV storage ring, a dedicated small-angle X-ray scattering (SAXS) beamline has been installed with an in-achromat superconducting wiggler insertion device of peak magnetic field 3.1 T. The vertical beam divergence from the X-ray source is reduced significantly by a collimating mirror. Subsequently the beam is selectively monochromated by a double Si(111) crystal monochromator with high energy resolution (DeltaE/E approximately 2 x 10(-4)) in the energy range 5-23 keV, or by a double Mo/B4C multilayer monochromator for 10-30 times higher flux ( approximately 10(11) photons s(-1)) in the 6-15 keV range. These two monochromators are incorporated into one rotating cradle for fast exchange. The monochromated beam is focused by a toroidal mirror with 1:1 focusing for a small beam divergence and a beam size of approximately 0.9 mm x 0.3 mm (horizontal x vertical) at the focus point located 26.5 m from the radiation source. A plane mirror installed after the toroidal mirror is selectively used to deflect the beam downwards for grazing-incidence SAXS (GISAXS) from liquid surfaces. Two online beam-position monitors separated by 8 m provide an efficient feedback control for an overall beam-position stability in the 10 microm range. The beam features measured, including the flux density, energy resolution, size and divergence, are consistent with those calculated using the ray-tracing program SHADOW. With the deflectable beam of relatively high energy resolution and high flux, the new beamline meets the requirements for a wide range of SAXS applications, including anomalous SAXS for multiphase nanoparticles (e.g. semiconductor core-shell quantum dots) and GISAXS from liquid surfaces.
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
authors.forename: Din Goa
authors.initials: DG
authors.lastname: Liu
authors.forename: Chien Hung
authors.initials: CH
authors.lastname: Chang
authors.forename: Chin Yen
authors.initials: CY
authors.lastname: Liu
authors.forename: Shih Hung
authors.initials: SH
authors.lastname: Chang
authors.forename: Jwei Ming
authors.initials: JM
authors.lastname: Juang
authors.forename: Yen Fang
authors.initials: YF
authors.lastname: Song
authors.forename: Kuan Li
authors.initials: KL
authors.lastname: Yu
authors.forename: Kuei Fen
authors.initials: KF
authors.lastname: Liao
authors.forename: Ching Shiang
authors.initials: CS
authors.lastname: Hwang
authors.forename: Hok Sum
authors.initials: HS
authors.lastname: Fung
authors.forename: Ping Chung
authors.initials: PC
authors.lastname: Tseng
authors.forename: Chi Yi
authors.initials: CY
authors.lastname: Huang
authors.forename: Liang Jen
authors.initials: LJ
authors.lastname: Huang
authors.forename: Shih Chun
authors.initials: SC
authors.lastname: Chung
authors.forename: Mau Tsu
authors.initials: MT
authors.lastname: Tang
authors.forename: King Long
authors.initials: KL
authors.lastname: Tsang
authors.forename: Yu Shan
authors.initials: YS
authors.lastname: Huang
authors.forename: Chien Kuang
authors.initials: CK
authors.lastname: Kuan
authors.forename: Yi Chih
authors.initials: YC
authors.lastname: Liu
authors.forename: Keng S
authors.initials: KS
authors.lastname: Liang
authors.forename: U Ser
authors.initials: US
authors.lastname: Jeng