mcgeometry 0.1.0

Python tools to build MCNP geometry inputs.

MCgeometry

MCgeometry is a lightweight Python module for building MCNP geometry inputs from Python objects.

It provides containers for:

• surfaces (Surfaces)
• cells (Cells)
• materials (Materials)
• geometry/input writing (MCNP)

Repository layout

mcgeometry/
  __init__.py
  Surfaces.py
  Cells.py
  Materials.py
  MCNP.py
  Source.py
  Tally.py
  Traslation.py

Requirements

• Python 3.8+ (recommended)
• numpy is used by Source.py

Installation

From PyPI (after publication):

pip install mcgeometry

From source (repository root):

pip install -e .

This enables imports without manually setting PYTHONPATH.

Quick start

Example: create a simple world box containing one spherical cell and generate the MCNP input text.

from mcgeometry import Surfaces, Cells, Materials, MCNP

# 1) Define surfaces
surfaces = Surfaces()
surfaces.rpp("world", p_min=[-100, -100, -100], p_max=[100, 100, 100])
surfaces.sph("sphere", c=[0, 0, 0], r=10)

# 2) Define materials
materials = Materials()
materials.add_material("vacuum", rho=0.0)
materials.add_material("water", zzaid_comp=[["1001.80c", 2], ["8016.80c", 1]], rho=1.0)

# 3) Define cells
cells = Cells(surfaces, Outer_World_Surface="world")
cells.add_cell("sphere_cell", material="water", surface_name="sphere", imp_n=1)

# 4) Build MCNP input string
mcnp = MCNP(cells, surfaces, materials)
input_text = mcnp.Write()
print(input_text)

Examples

The examples/ folder contains runnable scripts:

• examples/basic_geometry.py: minimal geometry/material/cell setup and MCNP input generation.

Run:

python examples/basic_geometry.py

How to add this module to the Python path

If you are developing from this repository (without packaging/installing), Python must be able to find the project root (the folder that contains mcgeometry/).

Option 1: Temporary (current shell session)

From the repository root:

export PYTHONPATH="$PWD:$PYTHONPATH"

Then import normally:

from mcgeometry import Surfaces, Cells, Materials, MCNP

Option 2: Permanent (your shell profile)

Add this line to ~/.zshrc (zsh) or ~/.bashrc (bash):

export PYTHONPATH="/absolute/path/to/mcgeometry/repo:$PYTHONPATH"

Reload your shell:

source ~/.zshrc

Option 3: In code (single script/notebook)

import sys
sys.path.append("/absolute/path/to/mcgeometry/repo")

from mcgeometry import Surfaces, Cells, Materials, MCNP

Notes

• The package exports most core classes through mcgeometry/__init__.py, so importing from mcgeometry is the simplest entry point.
• The project currently uses the Traslation naming used in source files.
• The API now also includes standardized aliases:
  • class alias: Translation (keeps Traslation for compatibility)
  • MCNP.write* methods (keeps MCNP.Write* for compatibility)
• Source and Tally modules are currently under development and still need full validation before production use.