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<p>Dear McStas experts,</p>
<p>We are currently doing simulations with nested elliptical optics
and so far things ran quiet smoothly.</p>
<p>We generate the OFF file for the optic ourselves and use the
Guide_anyshape component.</p>
<p>We start with an outer layer and continue to add inner layers one
at a time.<br>
If we then get to optical components that have a high number of
levels we run into the problem, that McStas crashes resp. aborts
the simulation.</p>
<p>Output in that case reads:</p>
<p><font face="monospace"># McStas 2.7 - Nov. 27, 2020: [pid 64818]
Signal 11 detected SIGSEGV (Mem Error)<br>
# Simulation: NNb (NNb.instr) <br>
# Breakpoint: psd_monitor (Trace) 2.46 % ( 24574.0/ 1000000.0)<br>
# Date: Tue Jun 29 17:44:13 2021<br>
# Started: Tue Jun 29 17:44:13 2021<br>
# Last I/O Error: No such file or directory<br>
# McStas 2.7 - Nov. 27, 2020: Simulation stop (abort).</font></p>
<p>Or</p>
<font face="monospace"># McStas 2.7 - Nov. 27, 2020: [pid 66573]
Signal 10 detected [proc 0] SIGBUS (Bus error)<br>
# Simulation: NNb (NNb.instr) <br>
# Breakpoint: nested (Trace) 85.56 % ( 855555.0/ 1000000.0)<br>
# Date: Tue Jun 29 18:00:32 2021<br>
# Started: Tue Jun 29 18:00:28 2021</font><font face="monospace"><br>
# Last I/O Error: No such file or directory</font>
<p>There are many messages such as the following in the Mcstas
Window, too: <font face="monospace"><br>
</font><br>
<font face="monospace">Guide_anyshape: nested: Warning:
Reflectivity R=7.02318 > 1 lowered to R=1.<br>
Guide_anyshape: nested: Warning: Reflectivity R=7.02365 > 1
lowered to R=1.<br>
Guide_anyshape: nested: Warning: Reflectivity R=7.02412 > 1
lowered to R=1.<br>
Guide_anyshape: nested: Warning: Reflectivity R=7.0246 > 1
lowered to R=1.<br>
</font></p>
<p>I put an example of an instrument file (+OFF , +Source Component)
of a failed run for a 1m optic in the attachment.<br>
</p>
The trace run for instrument visualization works. <br>
We only run into the problem for short optics <=2 m, were a high
number of nested levels is needed to completely cover the cross
section.
<p>We run into the problem on Ubuntu 18.04 and MacOs Big Sur
machines.<br>
</p>
<p>Any ideas what's the problem? Are the spacing of the elliptical
getting to narrow, perhaps?<br>
<br>
Thanks in advance,</p>
<p>Richard<br>
</p>
<p><br>
</p>
<div class="moz-signature">-- <br>
<b>Richard Wagner</b><br>
Research Engineer<br>
Nuclear and Particle Physics Group<br>
Institut Laue-Langevin - ILL<br>
71, avenue des Martyrs<br>
CS 20156<br>
38042 Grenoble Cedex 9<br>
France <br>
<br>
<a href="www.ill.eu"><font color="#3984c6">www.ill.eu</font></a>
<p><br>
</p>
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