.. _sec-para-emode:

Event generator mode and kerma approximation
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.. list-table:: **e-mode** [#]_ 
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   * - Value
     - Explanation
   * -  | (D=0)
     -  | 
   * -  | =0
     -  | Simple sampling mode (non event generator mode).
   * -  | =1
     -  | Event generator mode Ver.1 (simple sampling + evaporation model).
   * -  | =2
     -  | Event generator mode Ver.2 (Ver.1 + accurate charged particle yields + accurate neutron energy distribution).
   * -  | =3
     -  | Event generator mode Ver. 3 (Ver. 2 + excitation states of residual nuclei)

When e-mode :math:`\ne` 0 and high-energy nuclear data libraries [#]_ are used, PHITS determines the reaction point using the total cross  section contained in the high-energy nuclear data libraries while the information on secondary particles is evaluated using the nuclear  reaction models.
Even in this case, the event-generator mode ver. 1 or 2 is still used for neutrons below 20 MeV.

.. [#] Including charged-particle and photo-nuclear data libraries.

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.. list-table:: **ikerman**
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   * - Value
     - Explanation
   * -  | (D=0)
     -  | Control parameters for the use of kerma approximation for neutrons in  [t-deposit].
   * -  | =0
     -  | Automatic selection.  Kerma approximation is not used when event generator mode is activated  (e-mode  :math:`\ge`  1).
   * -  | =1
     -  | Kerma approximation for neutrons is always not used.
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.. list-table:: **ikermap**
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   * - Value
     - Explanation
   * -  | (D=0)
     -  | Control parameters for the use of kerma approximation for photons in  [t-deposit].
   * -  | =0
     -  | Automatic selection.  Kerma approximation is not used when EGS5 mode is activated (negs=1,2),  or when emin(12) and emin(13) are set below 10 MeV.
   * -  | =1
     -  | Kerma approximation for photons is always not used.

The event generator mode (e-mode=1,2) is essential for calculation of event-by-event  quantities, such as detector signals, residual recoiled nuclides, lineal  energies, attributed to neutrons below 20 MeV.  The simple sampling mode (e-mode=0) reproduces secondary neutron spectra given by the nuclear data library better than e-mode=1,2. Note that e-mode=0 does not consider the conservation of energy and momentum. See  :numref:`sec-e-mode`  for further discussion of the use.

.. [#]  Until ver. 2.73, file(14)=trxcrd.dat is required for  e-mode=1,2.