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Dear Tom,<br>
once you use monochromator_curved.comp in an instrument simulation
with a "real" divergent beam, you are perfectly right, the simple
parallel beam relation doen't hold any more. At the time, when I
wrote the very first version of this comp for the thermal TAS PUMA
at FRM II, I "calibrated" RH, RV in dependence of A1 and L by
scanning RH, RV with a monitor at the sample position. The resulting
optimal RH(L,A1) and RV(L,A1) values were then used for further
simulations...<br>
Finally this corresponds somehow the procedure that you carry out on
the real instrument, when you initialize the monochromator.<br>
Best regards,<br>
Peter<br>
<br>
<br>
<div class="moz-cite-prefix">Am 21.08.2015 um 10:12 schrieb 陈彦舟:<br>
</div>
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cite="mid:5a55bf88.ab6a.14f4f50d5a3.Coremail.wokaoyan1981@126.com"
type="cite">
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<div>Dear all,<br>
<br>
In the simulation of monochromator_curved, the curvatures
approximation for parallel beam focusing to distance L with
monochromator rotation angle A1 are:<br>
RV=2*L*sin(DEG2RAD*A1);<br>
RH=2*L/sin(DEG2RAD*A1);<br>
However, in reality, the incoming neutron beam has a certain
divergence. My question is how to define the curvatures of
the monochromator considering the divergence?<br>
<br>
Best regards,<br>
Tom<br>
</div>
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<br>
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<pre class="moz-signature" cols="72">--
**********************************
Dr. Peter Link
Head of Neutron Optics
Heinz Maier-Leibnitz Zentrum (MLZ)
Technische Universität München
Lichtenbergstr. 1
85747 Garching
phone: +49 (0)89 289 14622
fax: +49 (0) 89 289 11694</pre>
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