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<p>Hi Peter,</p>
<p>find enclosed my example of an instrument where the
back-propagation fails.</p>
<p>The source is an MCPL_input component and I added a small
mcpl-input file, too.<br>
The particles in the MCPL file all start at z=1.84m<br>
</p>
<p>Without gravitation back-propagation works, with gravitation it
fails. <br>
</p>
<p>Any ideas, what could cause such a behavior?<br>
</p>
<p>Best, <br>
</p>
<p>Richard<br>
</p>
<p>PS: The PSI_source instrument you enclosed works for me (==
back-propagation with gravity turned on)<br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 26/07/2021 16:58, Peter Kjær
Willendrup wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1E57F302-67AA-4797-8FFE-D194AC9E0D68@fysik.dtu.dk">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<div class="" style="word-wrap:break-word;
line-break:after-white-space">Hi Richard,
<div class=""><br class="">
</div>
<div class=""><br class="">
</div>
<div class="">I just came back from vacation and had a look at
the issue you report. ALLOW_BACKPROP ought to work
irrespective of the gravity setting in fact.</div>
<div class=""><br class="">
</div>
<div class="">I tried putting your snippet of code into the
PSI_source instrument “behind” the source (see attached) - and
I don’t seem to reproduce your finding? </div>
<div class=""><br class="">
</div>
<div class="">Could the issue potentially be specific to the
instrument you are using it in? If you send me a copy (plus
need inputfiles etc.) I will have a closer look.</div>
<div class=""><br class="">
</div>
<div class="">(Feel free to do this outside the mailinglist if
you prefer. :) )</div>
<div class=""><br class="">
</div>
<div class=""><br class="">
</div>
<div class="">Best,</div>
<div class="">Peter</div>
<div class=""><br class="">
</div>
</div>
<div class="" style="word-wrap:break-word;
line-break:after-white-space">
<div class="">
<div><br class="">
<blockquote type="cite" class="">
<div class="">On 18 Jul 2021, at 00.14, Richard Wagner
<<a href="mailto:wagnerrichard@ill.fr" class=""
moz-do-not-send="true">wagnerrichard@ill.fr</a>>
wrote:</div>
<br class="x_Apple-interchange-newline">
<div class=""><span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">Dear All,</span><br class=""
style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">I have the following issue
with a Shape Component in a simulation. It is used to
filter neutrons that have not are not originating from
the moderator window.</span><br class=""
style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<font class="" style="font-size:12px; font-style:normal;
font-weight:normal; letter-spacing:normal;
text-align:start; text-indent:0px;
text-transform:none; white-space:normal;
word-spacing:0px; text-decoration:none"
face="monospace"><br class="">
COMPONENT Mod_Face = Shape(xwidth=.30,yheight=.24)<br
class="">
AT (0,0,0.16) RELATIVE ABSOLUTE<br class="">
EXTEND %{<br class="">
/* Propagate back to a small rectangle in front of
moderator */<br class="">
printf("(before) x=%g y=%g z=%g\n", x, y, z);<br
class="">
<span class="x_Apple-converted-space"> </span><br
class="">
ALLOW_BACKPROP;<br class="">
PROP_Z0;<br class="">
SCATTER;<br class="">
<span class="x_Apple-converted-space"> </span><br
class="">
printf("(after) x=%g y=%g z=%g\n", x, y, z); <span
class="x_Apple-converted-space"> </span><br class="">
printf("(if) %d\n", (fabs(x)> xwidth/2 ||
fabs(y)> yheight/2));<br class="">
/* Remove neutrons that are not from around the
moderators */<br class="">
if (fabs(x)> xwidth/2 || fabs(y)> yheight/2)<span
class="x_Apple-converted-space"> </span><br class="">
{<br class="">
printf("(absorbed) x=%g y=%g z=%g\n", x, y, z); <span
class="x_Apple-converted-space"> </span><br class="">
ABSORB; <span class="x_Apple-converted-space"> </span><br
class="">
}<br class="">
%}</font><br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">If I run the McStas
simulation with the --gravitation flag the back
propagation is not working.</span><br class=""
style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">Log entries will exemplaryly
read:</span><br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<div class="" style="white-space:pre-wrap; font-family:Helvetica; font-size:12px; font-style:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; word-spacing:0px; text-decoration:none; margin:0px">
<span class="" style="color:rgb(0,128,0)">(if) 0</span></div>
<div class="" style="white-space:pre-wrap; font-family:Helvetica; font-size:12px; font-style:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; word-spacing:0px; text-decoration:none; margin:0px">
<span class="" style="color:rgb(0,128,0)">(before) x=0.131648 y=0.00568935 z=1.84</span></div>
<div class="" style="white-space:pre-wrap; font-family:Helvetica; font-size:12px; font-style:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; word-spacing:0px; text-decoration:none; margin:0px">
<span class="" style="color:rgb(0,128,0)">(after) x=0.131648 y=0.00568935 z=1.84</span></div>
<p class="" style="white-space:pre-wrap; font-family:Helvetica; font-size:12px; font-style:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; word-spacing:0px; text-decoration:none; margin:0px">
<span class="" style="color:rgb(0,128,0)"></span></p>
<span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">And no neutrons will be
filtered out</span><br class=""
style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">With gravity set to 'off' I
get:</span><br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<div class="" style="white-space:pre-wrap; font-family:Helvetica; font-size:12px; font-style:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; word-spacing:0px; text-decoration:none; margin:0px">
<span class="" style="color:rgb(0,128,0)">(before) x=0.110096 y=0.118489 z=1.84</span></div>
<div class="" style="white-space:pre-wrap; font-family:Helvetica; font-size:12px; font-style:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; word-spacing:0px; text-decoration:none; margin:0px">
<span class="" style="color:rgb(0,128,0)">(after) x=-0.118996 y=-0.00294855 z=0</span></div>
<div class="" style="white-space:pre-wrap; font-family:Helvetica; font-size:12px; font-style:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; word-spacing:0px; text-decoration:none; margin:0px">
<span class="" style="color:rgb(0,128,0)">(if) 0</span></div>
<div class="" style="white-space:pre-wrap; font-family:Helvetica; font-size:12px; font-style:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; word-spacing:0px; text-decoration:none; margin:0px">
<span class="" style="color:rgb(0,128,0)">(before) x=-0.0518426 y=-0.0952835 z=1.84</span></div>
<div class="" style="white-space:pre-wrap; font-family:Helvetica; font-size:12px; font-style:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; word-spacing:0px; text-decoration:none; margin:0px">
<span class="" style="color:rgb(0,128,0)">(after) x=0.519784 y=-0.514964 z=0</span></div>
<div class="" style="white-space:pre-wrap; font-family:Helvetica; font-size:12px; font-style:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; word-spacing:0px; text-decoration:none; margin:0px">
<span class="" style="color:rgb(0,128,0)">(if) 1</span></div>
<div class="" style="white-space:pre-wrap; font-family:Helvetica; font-size:12px; font-style:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; word-spacing:0px; text-decoration:none; margin:0px">
<span class="" style="color:rgb(0,128,0)">(absorbed) x=0.519784 y=-0.514964 z=0</span></div>
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">So it works as intended.</span><br
class="" style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">Is this behavior as
expected? Or differently is backprop not working with
gravity turned on?</span><br class=""
style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">I use McStas 2.7 and need to
make the simulation with gravity.</span><br class=""
style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">Any ideas?</span><br
class="" style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">Best,</span><br class=""
style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<span class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">Richard</span><br class=""
style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<br class="" style="font-family:Helvetica;
font-size:12px; font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
<div class="x_moz-signature"
style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none">
--<span class="x_Apple-converted-space"> </span><br
class="">
<b class="">Richard Wagner</b><br class="">
Research Engineer<br class="">
Nuclear and Particle Physics Group<br class="">
Institut Laue-Langevin - ILL<br class="">
71, avenue des Martyrs<br class="">
CS 20156<br class="">
38042 Grenoble Cedex 9<br class="">
France<span class="x_Apple-converted-space"> </span><br
class="">
<br class="">
<a href="" class="" moz-do-not-send="true"><font
class="" color="#3984c6">www.ill.eu</font></a>
<div class="" style="white-space:pre-wrap">
</div>
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letter-spacing:normal; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; word-spacing:0px;
text-decoration:none; float:none;
display:inline!important">_______________________________________________</span><br
class="" style="font-family:Helvetica; font-size:12px;
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letter-spacing:normal; text-align:start;
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text-indent:0px; text-transform:none;
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text-decoration:none; float:none;
display:inline!important">mcstas-users mailing list</span><br
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style="font-family:Helvetica; font-size:12px;
font-style:normal; font-weight:normal;
letter-spacing:normal; orphans:auto; text-align:start;
text-indent:0px; text-transform:none;
white-space:normal; widows:auto; word-spacing:0px"
moz-do-not-send="true">mcstas-users@mcstas.org</a><br
class="" style="font-family:Helvetica; font-size:12px;
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</blockquote>
</div>
<br class="">
</div>
</div>
</blockquote>
<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>
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