[mcstas-users] McStas simulation of nested elliptical optic with many levels crashes

[Erik B Knudsen]

Dear Richard,
Thank you for the thorough and detailed report. We will take a look at 
your problem asap and report back.
cheers
Erik

On 29/06/2021 18:31, Richard Wagner wrote:
> Dear McStas experts,
> 
> We are currently doing simulations with nested elliptical optics and so 
> far things ran quiet smoothly.
> 
> We generate the OFF file for the optic ourselves and use the 
> Guide_anyshape component.
> 
> We start with an outer layer and continue to add inner layers one at a time.
> 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.
> 
> Output in that case reads:
> 
> # McStas 2.7 - Nov. 27, 2020: [pid 64818] Signal 11 detected SIGSEGV 
> (Mem Error)
> # Simulation: NNb (NNb.instr)
> # Breakpoint: psd_monitor (Trace) 2.46 % (   24574.0/ 1000000.0)
> # Date:      Tue Jun 29 17:44:13 2021
> # Started:   Tue Jun 29 17:44:13 2021
> # Last I/O Error: No such file or directory
> # McStas 2.7 - Nov. 27, 2020: Simulation stop (abort).
> 
> Or
> 
> # McStas 2.7 - Nov. 27, 2020: [pid 66573] Signal 10 detected [proc 0] 
> SIGBUS (Bus error)
> # Simulation: NNb (NNb.instr)
> # Breakpoint: nested (Trace) 85.56 % (  855555.0/ 1000000.0)
> # Date:      Tue Jun 29 18:00:32 2021
> # Started:   Tue Jun 29 18:00:28 2021
> # Last I/O Error: No such file or directory
> 
> There are many messages such as the following in the Mcstas Window, too:
> 
> Guide_anyshape: nested: Warning: Reflectivity R=7.02318 > 1 lowered to R=1.
> Guide_anyshape: nested: Warning: Reflectivity R=7.02365 > 1 lowered to R=1.
> Guide_anyshape: nested: Warning: Reflectivity R=7.02412 > 1 lowered to R=1.
> Guide_anyshape: nested: Warning: Reflectivity R=7.0246 > 1 lowered to R=1.
> 
> I put an example of an instrument file (+OFF , +Source Component) of a 
> failed run for a 1m optic in the attachment.
> 
> The trace run for instrument visualization works.
> 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.
> 
> We run into the problem on Ubuntu 18.04 and MacOs Big Sur machines.
> 
> Any ideas what's the problem? Are the spacing of the elliptical getting 
> to narrow, perhaps?
> 
> Thanks in advance,
> 
> Richard
> 
> 
> -- 
> *Richard Wagner*
> Research Engineer
> Nuclear and Particle Physics Group
> Institut Laue-Langevin - ILL
> 71, avenue des Martyrs
> CS 20156
> 38042 Grenoble Cedex 9
> France
> 
> www.ill.eu <www.ill.eu>
> 
> 
> 
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> 

-- 
Erik Bergbäck Knudsen, Research Engineer         | DTU | morituri
NEXMAP, DTU Fysik, DK-2800 Kgs. Lyngby, Denmark  |<>-<>|    te
phone: (+45) 2132 6655                           |<>-<>| salutant