A Level-2 Biosafety Beamline for Macromolecular Crystallography at SSRF

摘要

A biosafety level-2 beamline for macromolecular crystallography is constructing at SSRF, which is one of the beamlines in phase-II beamline project approved at 2016 by the central government of China. This beamline will provide the capability of conducting the experiment on determination of the virus-related protein structure from crystals. To fulfill this aim, the end station is emphasized on the biosafety design which must meet the Chinese laws and regulations. For the limited source of insertion section in the storage ring, the beamline will be one of the canted beamline, sharing the insertion with the ultra-small angle X-ray scattering beamline. The photon source will be a 1.6 m long, in-vacuum undulator with period of 22 mm. The optics will consist of a deflection flat mirror to increase the distance of two canted beamline, a cryogenically cooled Si(111) doublecrystal monochromator and focusing mirrors. The focus scheme is realized with two-stage focus scheme in horizontal and one stage focus in vertical direction. At the sample position the focused beam is 20 micron in horizontal and 10 micron in vertical. The beam size could be changed by inserting the compound refractive lens. The beamline will deliver a high flux beam in the 7-18 keV energy range, with the energy resolution of AE/E~2×10~(-4). In addition to the main beamline, the endstation will be negative pressure control and be functional divided to meet the biosafety regulations. This report shows the current status of the beamline design.