Reproduction factor from macroscopic cross sections in fuel
===========================================================

Reproduction factor can be found using the macroscopic fissure and absorption cross
sections in the fuel and the average number of neutrons produced per fission.

**Links:**

#. `Wikipedia, first row in table <https://en.wikipedia.org/wiki/Four_factor_formula>`__.

.. py:currentmodule:: symplyphysics.laws.nuclear.reproduction_factor_from_macroscopic_fission_cross_section

.. py:data:: neutrons_per_fission

    Average number of neutrons produced per fission. See :attr:`~symplyphysics.symbols.basic.particle_count`.

Symbol:
    :code:`nu`

Latex:
    :math:`\nu`

Dimension:
    :code:`dimensionless`


.. py:data:: macroscopic_fission_cross_section

    :attr:`~symplyphysics.symbols.nuclear.macroscopic_cross_section` of fission *in the fuel*.

Symbol:
    :code:`Sigma_ff`

Latex:
    :math:`\Sigma_\text{f}^\text{f}`

Dimension:
    :code:`1/length`


.. py:data:: macroscopic_absorption_cross_section

    :attr:`~symplyphysics.symbols.nuclear.macroscopic_cross_section` of absorption *in the fuel*.

Symbol:
    :code:`Sigma_af`

Latex:
    :math:`\Sigma_\text{a}^\text{f}`

Dimension:
    :code:`1/length`


.. py:data:: reproduction_factor

    Neutron :attr:`~symplyphysics.symbols.nuclear.reproduction_factor`.

Symbol:
    :code:`eta`

Latex:
    :math:`\eta`

Dimension:
    :code:`dimensionless`


.. py:data:: law

    :code:`eta = nu * Sigma_ff / Sigma_af`


    Latex:
        .. math::
            \eta = \frac{\nu \Sigma_\text{f}^\text{f}}{\Sigma_\text{a}^\text{f}}