[ Source ] section
==================================================

The source information can be set in this section. 
The source type is specified by the number **s-type=N** based on its geometry as in :numref:`tbl-stype` . 

The energy of the source particle can be given by **e0** for mono-energy or **e-type** for energy spectrum. [#]_
Unit of energy in [source] is MeV/n (MeV per nucleons) except for particles not the constitute of nucleon (photons, electrons, pions, muons etc).

.. _tbl-stype:

.. rst-class:: no-caption-number

.. list-table:: **s-type**
  :header-rows: 1

  * - source type
    - explanation
  * - **s-type = 1, (4)**
    - Cylinder (or circle, pencil)
  * - **s-type = 2, (5)**
    - Rectangular solid (or rectangle)
  * - **s-type = 3, (6)**
    - Gaussian (:math:`x,y,z` independent)
  * - **s-type = 7, (8)**
    - Generic parabola (:math:`x,y,z` independent)
  * - **s-type = 9, (10)**
    - Sphere or spherical shell
  * - **s-type = 11**
    - Phase-space source based on accelerator beam emittance.
  * - **s-type = 12**
    - Reading the data from decay-turtle output
  * - **s-type = 13, (14)**
    - Gaussian (:math:`xy` plane)
  * - **s-type = 15, (16)**
    - Generic parabola (:math:`xy` plane)
  * - **s-type = 17**
    - Reading dump file
  * - **s-type = 18, (19)**
    - Cone
  * - **s-type = 20, (21)**
    - Triangle prism
  * - **s-type = 22, (23)**
    - :math:`xyz`-mesh distribution
  * - **s-type = 24**
    - Tetra-mesh source
  * - **s-type = 26**
    - Surface definition source
  * - **s-type = 100**
    - User definition source. Edit the **usrsors.f** and compile PHITS.

In :numref:`tbl-stype`, numbers in the brackets were used until ver. 2.94.  
If both **e0** and **e-type** are defined from ver. 2.95, the energy is decided according to the previous procedure of **s-type**.  
For example, **e0** is used when **s-type = 1**, and the definition of **e-type** is used when **s-type = 4**.


The projectile direction is specified by three parameters:  
**dir**, **phi**, and **dom**.  
The relation between these is shown in :numref:`fig-source-direction`,  
in which the direction is noted as a thick arrow.  
**dir** is the direction cosine relative to the :math:`z` axis.  
**phi** is the azimuthal angle from the :math:`x` axis and is given in  
degrees; if not set by the user, the value of the azimuthal cosine is  
selected randomly.  
Using the parameter **dom** spreads the direction determined by  
**dir** and **phi** by the solid angle :math:`2\pi(1-\cos\psi)`, where  
:math:`\psi =` **dom** (in degrees).  
In the PHITS calculation, the angle is selected randomly within the  
solid angle.

By setting **dir = all**, the direction of the source beam becomes isotropic.  
To use a specific angular distribution, a subsection in the distribution based on numerical data or an analytic function starting from **a-type** is required.  

In **s-type = 9**, the definition of **dir** differs.  
In **s-type = 11** and **12**, **dir** can only be set to :math:`-1` or :math:`1`.


.. figure:: ./source-direction.png
  :width: 20em
  :alt: source direction
  :name: fig-source-direction

  Source direction and parameters **dir, phi, dom** .

.. toctree::

  ./source_1.rst
  ./source_2.rst
  ./s-type_1.rst
  ./s-type_2.rst
  ./s-type_3.rst
  ./s-type_7.rst
  ./s-type_13.rst
  ./s-type_15.rst
  ./s-type_9.rst
  ./s-type_11.rst
  ./s-type_12.rst
  ./s-type_18.rst
  ./s-type_20.rst
  ./s-type_22.rst
  ./s-type_24.rst
  ./s-type_26.rst
  ./s-type_17.rst
  ./s-type_100.rst
  ./source_3.rst
  ./source_4.rst
  ./source_5.rst
  ./source_6.rst
  ./source_7.rst

.. [#] Until version 2.94, **s-type** had to be used depending on the energy definition, for example, **s-type=1** with **e0** defined the cylinder source of mono-energy, while **s-type=4** with **e-type** defined that of the energy spectrum.