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Index

##### Image dictionary (imgCIF) version 1.5.4

# _diffrn_radiation.div_x_y_source

**Name:**

`'_diffrn_radiation.div_x_y_source'`
**Definition:**

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 X-ray 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 photon in XZ plane times the deviations
of the direction of the same photon in the YZ plane
around the mean source beam direction. This will be zero
for uncorrelated crossfire.
Note that some synchrotrons, this value is specified 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^.

**Type:** float

**Mandatory item:** no

Enumeration default: 0.0
**Category:** diffrn_radiation

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HTML version of draft dictionary created by modified version of makedicthtml by B. McMahon
from modified version of imgCIF dcitionary 1.3.2 which is subject to the following copyright:

Copyright © 2005 International Union of Crystallography