The INTEGRATE Command

The INTEGRATE command allows integration of arbitrary 2-D regions to a variety of 1-D scans. Presently, $2\theta$, D-Spacing, Q-Space, and equal radial distance element scans may be produced. The ZOOM IN command may be used to select a ROI for integration, and the MASK command may be used to mask-off ``bad'' pixels within the ROI so that their value do not influence the results of the integration.

First the EXPERIMENTAL GEOMETRY CONTROL FORM appears. An example of this form is shown in Figure 34, Page . The values may already have been defined e.g. within the TILT command. Clearly, these values are extremely important if the resulting scan is to be correct. When the values are correctly set click the O.K. button.

Next the CONTROL OF RADIAL, 2-THETA, OR Q SCAN RE-BINNING PARAMETERS control form appears. An example of this form is shown in Figure 36.

Figure 36: The CONTROL OF RADIAL, 2-THETA, OR Q SCAN RE-BINNING PARAMETERS Control Form

The following control parameters are available:

SCAN TYPE: Allows one of 4 different types of integrated scans to be selected:

2-THETA: This is an equal angle scan, equivalent to a $2\theta$ scan on a powder diffractometer. The scale is in degrees.

Q-SPACE: This is similar to the 2-THETA scan, but the output elements are in equal Q-range bins. The scale is in inverse nanometres. The definition of Q is $(4\pi / \lambda) sin(2\theta / 2)$, where $2\theta$ is the angle of the scattering as recorded on the detector relative to the direct beam.

RADIAL: This is an equal radial distance element scan. The scale is in millimetres.

D-SPACINGS: This converts pixel angles to equivalent D-spacings and outputs an scan in equal D-spacing distance pixels.

CONSERVE INT.: NO means that the output intensities are normalised by the number of contributing pixels (although geometrical corrections may be applied). This is appropriate for producing the equivalent of a $2\theta$ scan, and for a Q-space scan, but does not converse total intensity. For applications which require integrated intensities to be conserved, this should be set to YES.

POLARISATION: YES to apply a polarisation correction to the intensities during the integration.

FACTOR: This is the polarisation factor which is used if the polarisation correction is applied.

The polarisation factor is defined as $(I_h - I_v) / (I_h + I_v)$, where $I_h$ is the horizontal component and $I_v$ is the vertical component. (Horizontal should normally correspond to the X-direction of the image.)

GEOMETRY COR.: YES corrects a flat ``scan'' to the equivalent of a $2\theta$ scan, or a Q-space scan. (CONSERVE INT. should be set to NO). These are the effect of change of distance and obliqueness at higher angles for the flat image plate compared to a detector on a $2\theta$ arm, always facing the sample.

MAX ANGLE: Maximum angle of the output scan in degrees.

SCAN BINS: Number of bins in the output scan. This may be increased up to the size of the program array in the first dimension. Larger values lead to over-sampling with may help obtain better profiles.

When the required parameters have been set click on the O.K. button. Whilst the data is being integrated a progress report will appear in the terminal window.

The 2-D data will be replaced by the 1-D integrated scan, but the 2-D is saved in the ``memory'' and can be re-called using the EXCHANGE command.