Constructing an Isotropic Point Source with Rectangular Beam in MCNPX

  • Thread starter Alexander Camargo
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In summary, The conversation discusses the need for help in constructing a source on MCNPX, specifically an isotropic point source with a rectangular beam that simulates a standard mammography beam. The parameters in use are listed, including the source position, energy, particle type, and direction. The conversation also mentions using a 4 Pi Sr source with an adapted geometry instead of the SDEF parameters. A similar example from a book is referenced for further assistance.
  • #1
Alexander Camargo
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I need help to construct this source on mcnpx. I tried a lot of thing, but nothing worked. The source is a isotropic point source, but the beam is rectangular with dimensions of the same of scoring plane. The source is the standard mammography beam. Please, help.
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My parameters in use:
SDEF POS=0 0 66 ERG=d3 PAR=2 VEC=0 0 -1 DIR=d1 ext=d2 axs=1 0 0
SI1 -1 0.992733782 1 $ histogram for cosine bin limits
SP1 0 0.996366891 0.003633109 $ frac. solid angle for each bin
SB1 0 0 1 $ source bias for each bin
si2 0 .03 $ Focal spot with 3mm
sp2 -21 1

1643654682818.png
 
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  • #2
I need this source on sdef card. Any idea?

1643833567889.png
 
  • #3
I think I will not use the parameters of sdef but a 4 Pi Sr source with an adapted geometry

I see a similar example in this book : https://www.researchgate.net/publication/355444601_Radiation_problems_from_analytical_to_monte-carlo_solutions (chapter3 example 3.III)

1643868083157.png

hope it's help
 

FAQ: Constructing an Isotropic Point Source with Rectangular Beam in MCNPX

1. How do you define an isotropic point source in MCNPX?

An isotropic point source in MCNPX is defined as a point in space that emits particles in all directions with equal probability. This means that the source emits particles uniformly in all directions, creating a spherical radiation field around the source.

2. What is a rectangular beam in MCNPX?

A rectangular beam in MCNPX is a type of particle beam that is defined by its rectangular cross-section. This type of beam is often used to model particle sources in medical applications, such as linear accelerators used in radiation therapy.

3. How do you construct an isotropic point source with a rectangular beam in MCNPX?

To construct an isotropic point source with a rectangular beam in MCNPX, you will need to specify the source location, the number of particles to be emitted, and the energy and direction of the particles. You can then use the appropriate MCNPX input cards to define the geometry and properties of the rectangular beam and its emission characteristics.

4. What are the advantages of using a rectangular beam for an isotropic point source in MCNPX?

One advantage of using a rectangular beam for an isotropic point source in MCNPX is that it allows for more precise control over the direction and energy of the emitted particles. This can be useful for simulating specific types of radiation sources, such as medical linear accelerators. Additionally, using a rectangular beam can also improve computational efficiency in MCNPX simulations.

5. Are there any limitations to using a rectangular beam for an isotropic point source in MCNPX?

While using a rectangular beam for an isotropic point source in MCNPX has many advantages, there are also some limitations. For example, the rectangular beam may not accurately represent the true radiation field of a source if the source has a complex geometry or emits particles in a non-uniform pattern. It is important to carefully consider the source characteristics and the limitations of the rectangular beam model before using it in MCNPX simulations.

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