Extraneous Scattering Background in SANS Instruments

Three often overlooked sources of extraneous background scattering from surfaces in small angle neutron scattering (SANS) instruments have been examined in detail. Figure 1 shows schematically these sources: (i) the red ray shows a path from scattering of the direct beam off the beam stop which then scatters off the vessel lining and onto the detector; (ii) the blue ray shows a path from scattering from the sample onto the vessel lining and onto the detector; and (iii) the green ray shows a path from scattering from the sample onto the surrounding sample environment and onto the detector. The paper Barker et al. [1] describes scattering measurements, calculations and de-sign ideas to mitigate all three sources of background. affects accuracy of The from the rescatter from en-hance the empty The sample air from sample enhanced. The enhanced detector vessel 4% by nine position a further 16% the cross-section upon the sample-to-detector instruments using the at the NCNR, D33 at the and