Muon production model
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.. list-table:: **igmuppd**
   :header-rows: 0

   * - Value
     - Explanation
   * -  | (D=0)
     -  | Options for photon-induced muon-pair production.
   * -  | =0
     -  | This reaction mechanism is not considered.
   * -  | =1
     -  | This reaction mechanism is considered. If you take into account for multiple Coulomb scattering of the generated muons, please set nspred=-2.
.. rst-class:: no-caption-number

.. list-table:: **gmumul**
   :header-rows: 0

   * - Value
     - Explanation
   * -  | (D=1.0)
     -  | Multiplying factor to increase sampling probability of photon-induced muon-pair production.

- For muon pair production caused by positrons  :math:`(e^+ e^- \to \mu^+\mu^-)`  , please refer to the **[ User Defined Interaction ]** section.
- See the reference   [#]_  for more details of muon-pair production by igmuppd.

.. [#] \Y. Sakaki et al., Implementation of muon pair production in PHITS and verification by comparing with the muon shielding experiment at SLAC, Nucl. Instr. \& Meth. A 977, 164323 (2020).