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Item _diffrn_radiation.div_x_y_source

Description

              Beam crossfire correlation degrees^2^ between the
               crossfire laboratory X-axis component and the crossfire
               laboratory Y-axis component (see AXIS category).

               This is a characteristic of the xray beam as it illuminates
               the sample (or specimen) after all monochromation and
               collimation.

               This is the mean of the products of the deviations of the
               direction of each photons in X-Z plane times the deviations
               of the direction of the same photon in the Y-Z plane
               around the mean source beam direction.  This will be zero
               for uncorrelated crossfire.

               Note that some synchrotrons specify this value in
               milliradians^2, in which case a conversion would be needed.
               To go from a value in milliradians^2^ to a value in
               degrees^2, multiply by 0.180^2^ and divide by \p^2^.

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