Tem­per­ature dependence in Bragg edge neutron transmission measurements

A systematic study has been carried out to investigate the neutron transmission signal as a function of sample tem­per­ature. In particular, the experimentally de­ter­mined wavelength-dependent neutron attenuation spectra for a martensitic steel at tem­per­atures ranging from 21 to 700°C are com­pared with simulated data. A theoretical description that includes the Debye–Waller factor in order to describe the tem­per­ature influence on the neutron cross sections was im­plemented in the nxsPlotter software and used for the simulations. The analysis of the attenuation coefficients at varying tem­per­atures shows that the missing contributions due to elastic and inelastic scattering can be clearly distinguished: while the elastically scattered intensities decrease with higher tem­per­atures, the inelastically scattered intensities increase, and the two can be separated from each other by analysing unique sharp features in the form of Bragg edges. This study presents the first systematic approach to qu­antify this effect and can serve as a basis , for example, to correct measurements taken during in situ heat treatments, in many cases being a prerequisite for obtaining qu­anti­fiable results.