Difference between revisions of "Neutron pinball"
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==The Simulation== | ==The Simulation== | ||
| − | Photons with a Bremsstrahlung energy distribution are incident upon 64 thorium cylindrical targets. All thorium targets have 1 cm center-to-center spacing, a dia. of 0.4 cm, and a height of 8 cm. The target geometry is shown in the neutron flux plot below. The targets are surrounded by a cylindrical room filled with air, which has a radius equal to the distance between the target and the detectors (150 cm), and a height equal to the vertical extent of the detectors (76 cm). Upon the creation of a neutron from photofission, its initial direction of travel is logged, | + | Photons with a Bremsstrahlung energy distribution are incident upon 64 thorium cylindrical targets. All thorium targets have 1 cm center-to-center spacing, a dia. of 0.4 cm, and a height of 8 cm. The target geometry is shown in the neutron flux plot below. The targets are surrounded by a cylindrical room filled with air, which has a radius equal to the distance between the target and the detectors (150 cm), and a height equal to the vertical extent of the detectors (76 cm). Upon the creation of a neutron from photofission, its initial direction of travel is logged. When the neutron exits the cylindrical room, the direction of travel as seen by a detector placed at the same point is compared to it's initial direction of travel. |
[[File:Neutronflux.png|400 px|thumb|center|A uniform plane source of Bremsstrahlung photons, traveling from left to right, induce photofission in the targets. The rate of neutron production is represented by the color. ]] | [[File:Neutronflux.png|400 px|thumb|center|A uniform plane source of Bremsstrahlung photons, traveling from left to right, induce photofission in the targets. The rate of neutron production is represented by the color. ]] | ||
Revision as of 02:18, 30 January 2016
The Simulation
Photons with a Bremsstrahlung energy distribution are incident upon 64 thorium cylindrical targets. All thorium targets have 1 cm center-to-center spacing, a dia. of 0.4 cm, and a height of 8 cm. The target geometry is shown in the neutron flux plot below. The targets are surrounded by a cylindrical room filled with air, which has a radius equal to the distance between the target and the detectors (150 cm), and a height equal to the vertical extent of the detectors (76 cm). Upon the creation of a neutron from photofission, its initial direction of travel is logged. When the neutron exits the cylindrical room, the direction of travel as seen by a detector placed at the same point is compared to it's initial direction of travel.
Results
12% of neutrons scattered in the thorium cylinders alone, and 14% scattered when air was included. The histogram below shows that if a neutron did scatter, it most likely did so at an unacceptable angle. Neutrons that didn't undergo any interaction are not included in this plot.
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Effect of room air
About 2% of neutrons were scattered in the air. Below is a histogram of neutron deflection angles, as seen by the detector, when neutron-thorium interaction was turned off. Neutrons that didn't undergo any interaction are not included in this plot.
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