From: Giuseppe Battistoni (Giuseppe.Battistoni@mi.infn.it)
Date: Fri Apr 29 2005 - 09:18:21 CEST
Here below you can find an example on how to define correctly in FLUKA
air at 273 K, standard pressure. I called this material (compound)
AIR50. In order to be careful to repeat exactly the same recipe in
building the pemf file, I also add the .peg input.
Giuseppe
MATERIAL 7.0 14.007 0.001251 5.0 NITROGEN
MATERIAL 18.0 39.948 0.00178 7.0 ARGON
MATERIAL 8.0 15.999 0.001429 8.0 OXYGEN
*
MATERIAL 0.001293 14.0 AIR50
COMPOUND -.9256E-03 5.0 -.2837E-03 8.0 -.01572E-3 7.0 AIR50
MAT-PROP 1.000 14.0000 14.0000 1.0000
Peg file (Ecut = 1 MeV for e+e-, 0.1 MeV for photons):
MIXT
$INP
NE = 3,
RHO = 0.001293,
RHOZ= 0.9256E-3 0.2837E-3 0.01572E-3,
GASP= 1.,
IRAYL=1,
$END
AIR50 AIR50
N O AR
ENER
$INP AE=1.511,UE=1000001.,AP=.100,UP=1000000. $END
PWLF
$INP NALE=600,NALG=800,NALR=100 $END
DECK
$INP $END
TEST
$INP $END
On Fri, 29 Apr 2005 adwasil@poczta.onet.pl wrote:
> Date: Fri, 29 Apr 2005 08:49:55 +0200
> From: adwasil@poczta.onet.pl
> To: fluka-discuss@fluka.org
> Subject: Low energy neutron xsec not found for some media
>
>
> I've defined AIR material myself. But something is still not correct. I've obtained a massage **** Low energy neutron xsec not found for some media 4 5 ****. I think all used materials such as NITROGEN, OXYGEN, ARGON and CARBON are defined in FLUKA neutron library. Should I switch some option/command on to use cross section of these elements for compound (AIR)?
> What am I still doing wrong?
> Best regards
> Adam
>
> file.inp:
> TITLE
> Electron to photon to neutron on tungsten
> DEFAULTS PRECISIO
> *23456789 123456789 123456789 123456789 123456789 123456789 123456789 123456789
> BEAM -0.007 ELECTRON
> BEAMPOS 0. 0. -30. 0. 0.
> EVENTYPE 2. DPMJET
> GEOBEGIN COMBINAT
> geometry definition
> SPH 1 0. 0. 0. +9000000.
> RPP 2-1000000. +1000000. -1000000. +1000000. -1000000. +1000000.
> SPH 3 0. 0. 0. +100.
> RCC 4 0. 0. -3.5 0. 0. 7.
> 10.
> RPP 5 -20. +20. -20. +20. +100.1 +100.2
> END
> * black hole region
> 1 5 +1 -2
> * vacuum around (outer)
> 2 5 +2 -3 -5
> * air around (inner)
> 3 5 +3 -4
> * tungsten target region (7cm thick, 10cm radius)
> 4 5 +4
> * forward detector region
> 5 5 +5
> END
> GEOEND
> *---o---- ----1---- ----2---- ----3---- ----4---- ----5---- ----6---- ----7----
> * Z Mass Dens[g/cm3] Index Not.used Name
> *MATERIAL 74. 184. 19.3 23. TUNGSTEN
> *MATERIAL 4. 9.0122 1.848 5. BERYLLIU
> MATERIAL 18. 39.948 1.662E-3 26. ARGON
> MATERIAL 0. 0. 0.0012048 24. AIR
> COMPOUND -9.1E-4 7. 2.79E-4 8. 1.55E-5 26. AIR
> COMPOUND 1.49E-7 6. AIR
> *
> *---o---- ----1---- ----2---- ----3---- ----4---- ----5---- ----6---- ----7----
> *
> *ASSIGNMAT (material==>region)
> * tungsten target
> ASSIGNMAT 23. 4.
> * forward detector region
> ASSIGNMAT 24. 5.
> * Outer vacuum
> ASSIGNMAT 2. 2.
> * Inner air
> ASSIGNMAT 24. 3.
> * External Black Hole
> ASSIGNMAT 1. 1.
> PHOTONUC 1. 0. 0. 4. 24. 1.
> LAM-BIAS 0. 0.00005 0. 7.
> *23456789 123456789 123456789 123456789 123456789 123456789 123456789 123456789
> *---o---- ----1---- ----2---- ----3---- ----4---- ----5---- ----6---- ----7----
> *EMF EMF-OFF
> * **** Scoring ****
>
> USRBDX +1. 7. -31. 3. 2. PHOTON
> USRBDX +0.02 300. 1. &
> USRBDX +1. 3. -32. 3. 2. ELECTRON
> USRBDX +0.02 300. 1. &
> USRBDX +1. 8. -33. 3. 2. NEUTRON
> USRBDX +0.02 +1.E-5 300. 1. &
> *---o---- ----1---- ----2---- ----3---- ----4---- ----5---- ----6---- ----7----
> USRBDX +1. 7. -41. 5. 2. PHOTON
> USRBDX +0.02 300. 1. &
> USRBDX +1. 3. -42. 5. 2. ELECTRON
> USRBDX +0.02 300. 1. &
> USRBDX +1. 8. -43. 5. 2. NEUTRON
> USRBDX +0.02 +1.E-5 300. 1. &
> RANDOMIZE 1.
> *---o---- ----1---- ----2---- ----3---- ----4---- ----5---- ----6---- ----7----
> START 50. 1.0
> STOP
>
>
> On Thu, 28 Apr 2005, 20:10 Alberto Fasso wrote
> > FLUKA neutron cross sections are for single elements or isotopes, not for
> > compounds and mixtures. The error message is due to the fact that no cross
> > section with a name AIR* can be found in the neutron library.
> > But this just one of many reasons why pre-defined compound materials
> > (those with a * in their name) should NEVER be used. They are there for
> > historical reasons, but their use can give problems, or at least
> > inaccurate results. I hope that they will disappear in the next FLUKA
> > release.
> >
> > Alberto
> >
> > On Thu, 28 Apr 2005 adwasil@poczta.onet.pl wrote:
> > > I try to find a difference in neutron transport in vacuum and air. that
> > > While I'm using vacuum instead of air everything is OK, but wile I'm
> > > using fluka material 24 I obtain an error massage **** Low energy neutron
> > > xsec not found for some media 1 2 ****.
> > > What am I doing wrong?
> > > Best regards
> > > Adam
>
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