<div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small;color:#0b5394">Dear Erik,</div><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small;color:#0b5394"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small;color:#0b5394">Thank you very much. I appreciate your help.</div><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small;color:#0b5394">I would like to attach you the *.instr file and the *.lau file.</div><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small;color:#0b5394"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small;color:#0b5394">My objective is to simulate the backscattering reflections from the 111 and 311 peaks from silicon.</div><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small;color:#0b5394"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small;color:#0b5394">Thank you.</div><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small;color:#0b5394">Kind regards.</div><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small;color:#0b5394"><br></div></div><div class="gmail_extra"><br clear="all"><div><div dir="ltr"><b><font color="#0b5394">Jesús P. de Vicente.-</font></b></div></div>
<br><div class="gmail_quote">2014-09-09 12:51 GMT+02:00 Erik Bergbäck Knudsen <span dir="ltr"><<a href="mailto:erkn@fysik.dtu.dk" target="_blank">erkn@fysik.dtu.dk</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Dear Jesus,<br>
<br>
I believe there could be something wrong with your definition of unit<br>
cell vectors for Si. For instance, in your case, the angle between a and<br>
b is 60 deg. which does not fit with the cubic structure that Si<br>
generally exhibits. I'm not sure about the lengths of the unit cell<br>
vectors either: |a| = 3.84 Å does not seem right.<br>
<br>
To simply exclude the .lau file from the crystal definition will have<br>
the effect of completely disregarding coherent scattering in the<br>
simulation - you will therefore only see the contribution from<br>
incoherent scattering, which is probably not what you intended.<br>
<br>
To tell you exactly what the _right_ way to use Single_crystal as an<br>
analyzer is very difficult, as there are many ways. We'd be happy to<br>
help you find the right way for you, but to do so, we will need more<br>
details on what it is you're actually trying to do. If you attach a copy<br>
of the .instr file and whatever extra files that are needed to run your<br>
simulation we may be able to help you accomplish your task.<br>
<br>
kind regards and happy simulating<br>
Erik B Knudsen<br>
<span class=""><br>
On 09/08/2014 05:13 PM, Jesús P. de Vicente wrote:<br>
> Dear McStas team,<br>
><br>
> I am trying to perform simulations with a silicon analyzer.<br>
><br>
</span>> I use the *Single_crystal* component. For graphite material everything<br>
> works fine:<br>
> // *PG* *************************<br>
<span class="">> mosaic = 48,<br>
> reflections = "C_graphite.lau", barns=0,<br>
> ax=0, ay=2.14, az=-1.24,<br>
> bx = 0, by = 0, bz = 2.47,<br>
> cx = 6.71, cy = 0, cz = 0,<br>
> sigma_abs = 0.014, sigma_inc = 0.004,<br>
> //**************************<br>
><br>
> But I do not get to work with silicon material. I use the following syntax:<br>
</span>> // *Si* *************************<br>
<span class="">> reflections = "Si.lau", barns=0,<br>
> mosaic = 0.1, delta_d_d = 3.10e-4,<br>
> sigma_abs = 0.171, sigma_inc = 0.004,<br>
> ax = 2.715, ay = 2.715, az = 0.0,<br>
> bx = 0.0, by = 2.715, bz = 2.715,<br>
> cx = 2.715, cy = 0.0, cz = 2.715,<br>
> //**************************<br>
><br>
> I built a Si.lau file from the a Si.cif file using Crystallographica<br>
> software.<br>
> I have tried lot of configurations, but I got always lot of peaks with<br>
> the backscatteing configuration. I tried also the simulation without the<br>
> reflection *.lau file but I have no peaks.<br>
><br>
> Do you know what would be the right way to perform a simulation with a<br>
> silicon analyzer using the Single_crystal component?<br>
><br>
> Thank you very much for your help.<br>
> Kind regards.<br>
><br>
><br>
><br>
</span>> *Jesús P. de Vicente.-*<br>
><br>
><br>
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><br>
<span class="HOEnZb"><font color="#888888"><br>
--<br>
Erik Bergbäck Knudsen, Research Engineer | DTU | morituri<br>
NEXMAP, DTU Fysik, DK-2800 Kgs. Lyngby, Denmark |<>-<>| te<br>
phone: <a href="tel:%28%2B45%29%202132%203151" value="+4521323151">(+45) 2132 3151</a>, mobile: <a href="tel:%28%2B45%29%203123%206184" value="+4531236184">(+45) 3123 6184</a> |<>-<>| salutant<br>
</font></span></blockquote></div><br></div>