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DNS Powder Elastic - Options Tab

Wavelength sets the wavelength of the neutron beam. If Get from Data is checked, then the wavelength is read from the data files. If the selected data files have a different wavelength, or the wavelength does not match the corresponding frequency of the velocity selector, a warning will be given to the user and Get from Data checkbox will be unselected. In this case, the wavelength will have to be set manually by the user.

Normalisation can be used to select whether the dataset should be normalised by measurement time or monitor counts.

Corrections should be selected to activate various options for data reduction.

Detector Efficiency Correction corrects for different detector efficiencies by normalizing selected sample data on vanadium measurements. When the detector efficiency correction checkbox is selected, the user must select the corresponding vanadium and empty container measurements under the Standard Data view of the Data tab. The empty measurement is required because background subtraction from vanadium is mandatory. Detector efficiencies will be evaluated for each of those vanadium “field” channels that correspond to the user-selected sample “field” channels, unless either from Sum Vanadium SF and NSF and Ignore Vanadium Fields options is additionally selected by the user (both options can’t be selected at the same time).

Sum Vanadium SF and NSF calculates detector efficiencies by combining vanadium spin-flip (SF) and non-spin-flip (NSF) data for each of the vanadium polarization components that correspond to the selected polarisations (\(x, y\), or \(z\)) of the sample.

Ignore Vanadium Fields calculates detector efficiencies by combining all selected vanadium “fields”. In this case, the calculated detector efficiencies can be applied to any of the selected sample “fields”.

Flipping Ratio Correction corrects for the finite flipping ratio, using standard NiCr data. Similarly to the case with detector efficiency correction, when the flipping ratio option is selected, the corresponding empty measurement must also be selected (for the background subtraction from NiCr). Both, spin-flip and non-spin-flip measurements are required to be selected in Sample Data and Standard Data views of the Data tab.

Separation allows choosing between two possible separation options. XYZ polarization separation can be chosen for the analysis of magnetic samples. It requires at least x_sf, y_sf, z_sf, and z_nsf sample channels to be selected by the user. As a result of the \(xyz\)-separation analysis, the user will be able to additionally visualize magnetic, nuclear coherent, and spin incoherent contributions to the resulting intensity function. Coherent/Incoherent is helpful for the analysis of non-magnetic samples and requires only SF and NSF channels to be selected. As a result, the user can visualize nuclear coherent and spin-incoherent contributions to each of the selected sample polarisation components.

When the Automatic Binning checkbox is selected, the interface will determine the minimum and maximum values for the scattering angle \(2 \theta\) based on the detector bank rotation angles of the selected sample data files. The default bin size value is chosen to be \(0.5^{\circ}\). When Automatic Binning is unselected, the user can manually choose the desired bin size value, as well as the scattering angle range that will be used in the figure under the Plotting tab.