Application of silver behenate powder for wavelength calibration of a SANS instrument - a comprehensive study of experimental setup variations and data processing techniques

Silver behenate powder [CH3(CH2)(20)COOAg] is one of the very few materials featuring cold neutron Bragg reflections in the angular range of 4-26 degrees (2 theta) accessible to small-angle neutron scattering (SANS) instruments. These reflections can be analysed with Bragg's law to determine the wavelength of the primary beam produced by the monochromator of the SANS instrument. Compared with the usual time-of-flight (TOF) method for wavelength calibration, this method does not require any additional time-resolving equipment for the instrument. An extensive study has been performed to determine the optimum parameters for the experimental setup and for the data processing procedure. The results of wavelength calibrations using silver behenate and TOF measurements are compared.