Macroscopic cross section from mean free path
=============================================

Macroscopic cross section is the inverse of mean free path of neutrons. As an example,
the greater the absorption cross section of a material is, the shorter the mean free
path of neutrons is and the closer to the surface the neutron absorption will occur.

**Links:**

#. `NuclearPower, section "Mean Free Path" <https://www.nuclear-power.com/nuclear-power/reactor-physics/nuclear-engineering-fundamentals/neutron-nuclear-reactions/macroscopic-cross-section/>`__.

..
    TODO: fix file name

.. py:currentmodule:: symplyphysics.laws.nuclear.macroscopic_cross_section_from_free_mean_path

.. py:data:: mean_free_path

    :attr:`~symplyphysics.symbols.thermodynamics.mean_free_path` of neutrons.

Symbol:
    :code:`lambda`

Latex:
    :math:`\lambda`

Dimension:
    :code:`length`


.. py:data:: macroscopic_cross_section

    :attr:`~symplyphysics.symbols.nuclear.macroscopic_cross_section`.

Symbol:
    :code:`Sigma`

Latex:
    :math:`\Sigma`

Dimension:
    :code:`1/length`


.. py:data:: law

    :code:`Sigma = 1 / lambda`


    Latex:
        .. math::
            \Sigma = \frac{1}{\lambda}