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Hello Timur,
<p>When you simulate -n 1e6 neutrons, these are not exactly neutrons, but
neutron packs, associated to a weight which is given usually by the source.
The weight IS the intensity. DO NOT use the number of events. It has NOTHING
to do with the neutron flux or intensity, nor with the transmission. The
'strange units' you are talking are the intensities.
<br>If you want to simulate the transmission, place a monitor before and
after a section, and look for the intensity ratio (not N).
<p>Bye, Emmanuel.
<br>
<p>Timur Elzhov wrote:
<blockquote TYPE=CITE>On Thu, Jul 31, 2003 at 12:26:47PM +0200, Emmanuel
Farhi wrote:
<p>> The 'N' data has no physical sense. It is a number of simulation events
<br>> for a given data bin. You basically should not use that data, except
if
<br>> you wish to study the simulation statistics and efficiency (see Manual,
p
<br>> 41).
<br>> In McStas, a simulation event may be regarded as a pack of neutrons,
<br>> containing 'p' particules. When this event propagates, its 'filling'
<br>> decreases, and the total weight of the pack is the intensity 'I'
when
<br>> stored in monitor bins, even if the event is still there (and counts
for
<br>> '1' in 'N').
<br>OK! Bu, let's have a look at the exec string of my program:
<p> ./dn2-guide.out --ncount=1e+06 S=3.0
R0=1.00 ...
<p>and at the output:
<p> Detector: detect_inc_I=6.77255e+09 detect_inc_ERR=1.1166e+07
detect_inc_N=999931 "inc0003.0.dat"
<br> Detector: detect_out_I=1.98277e+08 detect_out_ERR=856286
detect_out_N=446104 "out0003.0.dat"
<p>"detect_inc" is detector at the guide entrance, and all the incoming
neutrons
<br>are directed to them. But, "detect_inc_N" is likely to correspond to
the total
<br>counts of neutrons, not "detect_inc_I". "detect_inc_I" expressed in
the
<br>strange units and have values of order of 7-8, while I've simulated
1e+6
<br>neutrons... I obviosly misunderstand something, excuse me please :-)
<p>--
<br>WBR,
<br>Timur.
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<pre>--
What's up Doc ?
--------------------------------------------
Emmanuel FARHI, <A HREF="http://www.ill.fr/tas/people/Farhi.html">http://www.ill.fr/tas/people/Farhi.html</A> \|/ ____ \|/
CS-Group ILL4/156, Institut Laue-Langevin (ILL) Grenoble ~@-/ oO \-@~
6 rue J. Horowitz, BP 156, 38042 Grenoble Cedex 9,France /_( \__/ )_\
Work :Tel (33/0) 4 76 20 71 35. Fax (33/0) 4 76 20 76 48 \__U_/</pre>
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