Resolution function determination for diffractometer over time of flight

Results of checking up the formulae for calculation of resolution functions in neutron spectrometry are presented. The diffractometer resolution function is measured by the time-of-flight method with an ideal monocrystal silicon 3.5 cm in diameter on the IBR-30 pulsed reactor. The neutron beam is extracted from the 30x40 cm surface of uncooled water moderator 4 cm thick at 12 deg to the normal. The resolution function calculation includes the time dispersion of the time-dependent neutron burst. The spectra are measured by the time-of-flight method at Bragg angles of 120 and 85 deg. Calculations made to be compared with experimental data do not comprise free parameters for matching. Flight distances, dimensions and orientation of the moderator, sample and detector, and also time dispersion of the thermal neutron burst constitute the initial data. The comparison of measured and corrected data with experimental values shows that they are in a fair agreement. As a rule, the discrepancy in the moment values does not exceed 10%. All the data summed up allow to draw a conclusion that a reliable method for calculating the resolution function has been developed and it may be used in data analysis and in planning experiments in diffraction by the time-of-flight method