title: Small-angle solution scattering using the mixed-mode pixel array detector.
abstract: Solution small-angle X-ray scattering (SAXS) measurements were obtained using a 128 × 128 pixel X-ray mixed-mode pixel array detector (MMPAD) with an 860 µs readout time. The MMPAD offers advantages for SAXS experiments: a pixel full-well of >2 × 10(7) 10 keV X-rays, a maximum flux rate of 10(8) X-rays pixel(-1) s(-1), and a sub-pixel point-spread function. Data from the MMPAD were quantitatively compared with data from a charge-coupled device (CCD) fiber-optically coupled to a phosphor screen. MMPAD solution SAXS data from lysozyme solutions were of equal or better quality than data captured by the CCD. The read-noise (normalized by pixel area) of the MMPAD was less than that of the CCD by an average factor of 3.0. Short sample-to-detector distances were required owing to the small MMPAD area (19.2 mm × 19.2 mm), and were revealed to be advantageous with respect to detector read-noise. As predicted by the Shannon sampling theory and confirmed by the acquisition of lysozyme solution SAXS curves, the MMPAD at short distances is capable of sufficiently sampling a solution SAXS curve for protein shape analysis. The readout speed of the MMPAD was demonstrated by continuously monitoring lysozyme sample evolution as radiation damage accumulated. These experiments prove that a small suitably configured MMPAD is appropriate for time-resolved solution scattering measurements.
authors.affiliation: Department of Physics, LASSP, Cornell University, Ithaca, NY, USA.
authors.forename: Lucas J
authors.initials: LJ
authors.lastname: Koerner
authors.forename: Richard E
authors.initials: RE
authors.lastname: Gillilan
authors.forename: Katherine S
authors.initials: KS
authors.lastname: Green
authors.forename: Suntao
authors.initials: S
authors.lastname: Wang
authors.forename: Sol M
authors.initials: SM
authors.lastname: Gruner
mesh_terms: D009113:Muramidase / Q000528:radiation effects / Q000648:ultrastructure; D011506:Proteins / Q000648:ultrastructure*; D053838:Scattering, Small Angle; D012996:Solutions / Q000737:chemistry; D014961:X-Ray Diffraction / Q000379:methods*
chemical_list: D011506:Proteins; D012996:Solutions; D009113:Muramidase