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<title>(IUCr) CIF Definition save__diffrn_radiation.polarizn_source_ratio</title>
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<p class="title">DRAFT DICTIONARY</p>
<p class="title"><font class="smalltitle"></font>CBF/imgCIF Extensions Dictionary</p>
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<p class="title">Draft version 1.5 for comment</p>
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<h5>Image dictionary (imgCIF) version 1.5.4</h5>
<h1>_diffrn_radiation.polarizn_source_ratio</h1><b>Name:</b><br /><tt class="cifdefinition">'_diffrn_radiation.polarizn_source_ratio'</tt>
<p><b>Definition:</b></p><pre class="cifdefinition">
(Ip-In)/(Ip+In), where Ip is the intensity
(amplitude squared) of the electric vector in the plane of
polarization and In is the intensity (amplitude squared)
of the electric vector in the plane of the normal to the
plane of polarization.
In the case of an unpolarized beam, or a beam with true
circular polarization, in which no single plane of
polarization can be determined, the plane is to be taken
as the XZ plane and the normal is parallel to the Y axis.
Thus, if there was complete polarization in the plane of
polarization, the value of
<a href="Idiffrn_radiation.polarizn_source_ratio.html" class="itemlink">_diffrn_radiation.polarizn_source_ratio</a> would be 1, and
for an unpolarized beam
<a href="Idiffrn_radiation.polarizn_source_ratio.html" class="itemlink">_diffrn_radiation.polarizn_source_ratio</a> would have a
value of 0.
If the X axis has been chosen to lie in the plane of
polarization, this definition will agree with the definition
of 'MONOCHROMATOR' in the Denzo glossary, and values of near
1 should be expected for a bending-magnet source. However,
if the X axis were perpendicular to the polarization plane
(not a common choice), then the Denzo value would be the
negative of <a href="Idiffrn_radiation.polarizn_source_ratio.html" class="itemlink">_diffrn_radiation.polarizn_source_ratio</a>.
See http://www.hkl-xray.com for information on Denzo and
Otwinowski & Minor (1997).
This differs both in the choice of ratio and choice of
orientation from <a href="Idiffrn_radiation.polarisn_ratio.html" class="itemlink">_diffrn_radiation.polarisn_ratio</a>, which,
unlike <a href="Idiffrn_radiation.polarizn_source_ratio.html" class="itemlink">_diffrn_radiation.polarizn_source_ratio</a>, is
unbounded.
Reference: Otwinowski, Z. & Minor, W. (1997). 'Processing of
X-ray diffraction data collected in oscillation mode.' Methods
Enzymol. 276, 307-326.
</pre>
<p><b>Type:</b> float</p>
<p class="pack"><b>Mandatory item:</b> no</p>
<br />The permitted range is [-1.0, 1.0]<br />
<p class="pack"><b>Category:</b> <a href="Cdiffrn_radiation.html" class="catlink">diffrn_radiation</a></p>
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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:
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