Measured performance of hybrid small-gap in-vacuum undulator 08ID-1 at the CLS intermediate energy storage ring

Abstract

The recent development of undulator in-vacuum technology has allowed intermediate energy storage rings, such the Canadian Light Source (CLS), to build high brilliance protein crystallography beamlines. The Canadian Macromolecular Crystallography Facility (CMCF) beamline 08ID-1 is the first small period (20 mm) hybrid small-gap in-vacuum undulator (SGU) to be employed at the CLS as a source of high harmonic, high brightness radiation (6.5 – 18 keV). The SGU was assembled and shimmed at the CLS Magnetic Mapping Facility. It is installed in the upstream part of straight section 8 of the CLS ring and chicaned inboard by 0.75 mrad. The downstream half of this section is reserved for future development. To achieve a maximum undulator field (B0) in conjunction with low sensitivity to radiation damage, a hybrid layout for the undulator is used with Sm2Co17 permanent magnets sandwiched between Vanadium Permendur ferromagnetic poles. To date, operations in the 6.5 – 18 keV energy range have been achieved using the 3rd to 9th harmonics, with gap sizes of 5.9 – 8.6 mm. Gaps smaller than 5.9 mm are not being used since in the 5.0 – 5.9 mm range the rms phase errors are larger than 2.5° and lower harmonics at larger gaps are being used instead. The goal of the present study is to measure the output spectrum for various gap sizes and compare these with theoretical expectations calculated from the magnetic characteristics of the undulator measured at the CLS Magnetic Mapping Facility. The 08ID-1 beamline now has several years of successful operation as a highly competitive, high brilliance beamline.