Difference between revisions of "MCNP Sim of Jack Converter"

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=Simulation inputs=
 
=Simulation inputs=
−
The vast majority photo-neutrons are produced from (G,n) on Tungsten-184.
+
MCNP input deck: [[File:MCNP Jack Converter.txt]].
 +
 
 +
The cross-section plots below show that the vast majority photo-neutrons are produced by (G,n) on Tungsten-184.
  
 
[[File:Wxs(Fiss,1n).png | 600px]]
 
[[File:Wxs(Fiss,1n).png | 600px]]
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==Assumptions==
 
==Assumptions==
−
The beam spot size was given a diameter of 0.5 cm, which was determined by the size of a burn mark on a converter that got hot during irradiation.
+
The beam spot size was given a diameter of 0.5 based off of the size of a burn mark on a converter that got hot during irradiation.
−
Electrons are 42 MeV and mono energetic.
+
Electrons are mono energetic.
  
 
=Results=
 
=Results=
−
==Neutrons==
+
The plots below show the energy distribution for neutrons exiting the converter at three different intervals of their angle w.r.t. the incident electron beam.
−
===Energy spectrum===
+
The energy spectrum of neutrons from the neutron-induced fission of U235 is shown on each plot, and is normalized to have the same integral flux as the simulated neutrons to facilitate comparison.
−
The plot below shows the energy distribution of neutrons exiting the converter at three different intervals of their angle w.r.t. the incident electron beam.
+
 
−
The neutron energy spectrum of the neutron-induced fission of U235 is also shown for comparison.  
+
The mean and median energy of fission neutrons from U235 is 1.94 MeV and 1.66 MeV, respectively. The mean and median energy of produced neurons are also shown on each plot.
−
[[File:JackConverterSimResult.png|1000px]]
+
 
 +
==Neutron energy spectra from 42 MeV electrons==
 +
=== 10 - 42 MeV neutrons===
 +
[[File:JacknConvertorSimHighErgNeutrons.png|900px]]
 +
 
 +
=== 6-10 MeV neutrons===
 +
With water in the converter (no significant difference with no water):
 +
 
 +
[[File:42MeVJackLin n(high erg).png|900px]]
 +
 
 +
===0.13-6 MeV neutrons===
 +
With water in the converter (no significant difference with no water):
 +
[[File:42MeVJackLin n-0.13(water).png|1000px]]
 +
 
 +
===0-0.1 MeV neutrons, with and without water===
 +
With water:
 +
 
 +
[[File:42MeVJackLin n thermal(water).png|900px]]
 +
 
 +
Without water:
 +
 
 +
[[File:42MeVJackLin n thermal(nowater).png|900px]]
 +
 
 +
==Neutron energy spectra from 30 MeV electrons==
 +
=== 6-10 MeV neutrons ===
 +
[[File:30MeVJackLin n(high erg).png|1000px]]
 +
 
 +
===0.13-7 MeV neutrons===
 +
[[File:30MeVJackLin n-0.13.png|1000px]]
 +
 
 +
===0-0.1 MeV neutrons ===
 +
With water:
 +
[[File:30MeVJackLin n thermal(water).png| 1000px ]]
  
−
===Misc===
+
==Neutron energy spectra from 20 MeV electrons==
−
The difference between the U235 neutron spectrum and the energy spectrum from the converter may be partially due to moderation of neutrons by H2O. The plot below demonstrates this point, which registers the energy of each photo-neutron immediately after emission, as opposed to after the photo-neutrons exit the converter.
+
=== 6-10 MeV neutrons ===
 +
Not enough statistics.
  
−
[[File:JackConverterSimResult(no moderation).png|600px]]
+
===0.13-6 MeV neutrons===
 +
[[File:20MeVJackLin n-0.13.png|1000px]]
  
−
Below is a plot of the rate of neutron production as the beam traverses through the converter. Zero corresponds to where the beam enters the titanium window.
+
===0-0.1 MeV neutrons ===
−
[[File:JackConverterNeutronProduction.png| 600 px]]
+
with water:
 +
[[File:20MeVJackLin n thermal(water).png|1000px]]
  
−
==Photons==
+
==Photon energy spectra from 42 MeV electrons==
−
The plot below shows the energy distribution of photons exiting the converter at three different intervals of their angle w.r.t. the incident electron beam
+
The plot below shows the energy distribution of photons exiting the converter for four different ranges of angle w.r.t. the incident electron beam
  
−
[[File:JackConverterPhotonErg.png | 700 px]]
+
[[File:42MeVJack photons.png | 1000 px]]

Latest revision as of 20:26, 25 September 2018

Simulation inputs

MCNP input deck: File:MCNP Jack Converter.txt.

The cross-section plots below show that the vast majority photo-neutrons are produced by (G,n) on Tungsten-184.

Wxs(Fiss,1n).png

Geometry

Profile view of converter geometry. Distances are in cm. There are two thin (0.001 inch) titanium plates, one on the far left and another on the far right of the convertor, but they are too small to be seen in this diagram. 0.2 cm of water separates each of the three 0.15 cm thick tungsten plates.
Front view of convertor geometry. Distances are in cm.

Materials legend for figures:

JackSimMCNPLegend.png









.

Assumptions

The beam spot size was given a diameter of 0.5 based off of the size of a burn mark on a converter that got hot during irradiation. Electrons are mono energetic.

Results

The plots below show the energy distribution for neutrons exiting the converter at three different intervals of their angle w.r.t. the incident electron beam. The energy spectrum of neutrons from the neutron-induced fission of U235 is shown on each plot, and is normalized to have the same integral flux as the simulated neutrons to facilitate comparison.

The mean and median energy of fission neutrons from U235 is 1.94 MeV and 1.66 MeV, respectively. The mean and median energy of produced neurons are also shown on each plot.

Neutron energy spectra from 42 MeV electrons

10 - 42 MeV neutrons

JacknConvertorSimHighErgNeutrons.png

6-10 MeV neutrons

With water in the converter (no significant difference with no water):

42MeVJackLin n(high erg).png

0.13-6 MeV neutrons

With water in the converter (no significant difference with no water): 42MeVJackLin n-0.13(water).png

0-0.1 MeV neutrons, with and without water

With water:

42MeVJackLin n thermal(water).png

Without water:

42MeVJackLin n thermal(nowater).png

Neutron energy spectra from 30 MeV electrons

6-10 MeV neutrons

30MeVJackLin n(high erg).png

0.13-7 MeV neutrons

30MeVJackLin n-0.13.png

0-0.1 MeV neutrons

With water: 30MeVJackLin n thermal(water).png

Neutron energy spectra from 20 MeV electrons

6-10 MeV neutrons

Not enough statistics.

0.13-6 MeV neutrons

20MeVJackLin n-0.13.png

0-0.1 MeV neutrons

with water: 20MeVJackLin n thermal(water).png

Photon energy spectra from 42 MeV electrons

The plot below shows the energy distribution of photons exiting the converter for four different ranges of angle w.r.t. the incident electron beam

42MeVJack photons.png

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