.. _[t-track]:

[ T-Track ] section
==================================================

This tally can be used to obtain the fluence in any specified region.
In this tally, the track length is evaluated whenever particles pass through a specified region, as shown in :numref:`tracklength`, and the sum of the track lengths in units of cm is scored.
Based on this, a particle fluence in units of [1/cm^2/source] is determined by dividing the scored track lengths by the volume of the region and the number of source particles.

As an example, information on the detector response in a specified region can be obtained by utilizing this tally.
Multiplying the fluence by the cross section, in units of cm^2, of the detector enables estimation of the number of counts in the response.

.. _tracklength:

.. figure:: ./tracklength.png
   :alt: [T-Track] tally: track length (solid line) is calculated.
   :width: 30%
   :align: center

   **[T-Track]** tally: track length (solid line) is calculated.

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

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

   * - value
     - explanation
   * -  | **reg, r-z, xyz, tet**
     -  | Mesh type: a mesh type subsection is required below this option.




.. include:: ../commontally/volume.rst
.. include:: ../commontally/iechrl.rst
.. include:: ../commontally/e-type.rst
.. rst-class:: no-caption-number

.. list-table:: **e-unit**
   :header-rows: 0

   * - value
     - explanation
   * - **MeV** (default), **keV**, **eV**, **nm**, **A0**
     - Unit of energy mesh.
       **nm** specifies wavelength in nanometers, **A0** specifies wavelength in angstroms. For massive particles, the de Broglie wavelength is used.
       When using **nm** or **A0**, unit must be 1, 4, 11, or 14.

.. include:: ../commontally/t-type.rst
.. rst-class:: no-caption-number

.. list-table:: **a-type**
   :header-rows: 0

   * - value
     - explanation
   * - **1, 2, -1, -2**
     - Angle mesh with :math:`\theta` degrees of freedom for **mesh=r-z**.
       See :numref:`sec-mesh-type` for mesh subsection format.

:math:`\theta` degrees of freedom can be set in **r-z** mesh of this tally.
The **a-type** mesh definition used to specify :math:`\theta` follows the same format as in the other angle mesh cases.
The :math:`\theta` dependence of results can be obtained by setting **axis=rad** or **axis=deg**, where rad and deg represent :math:`\theta` in radians and degrees, respectively.

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

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

   * - value
     - explanation
   * -  | **all** (default), particle name
     -  | Tally particle.




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

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

   * - value
     - explanation
   * - **eng, reg, x, y, z, r**
     - x axis value of output data.
   * - **tet**
     - x axis value of output data.
       This is active only with **mesh=tet**.
   * - **rad, deg**
     - x axis value of output data.
       These are variables for :math:`\theta` when **mesh=r-z**.
   * - **xy, yz, xz, rz**
     - 2-dimensional.
   * - **t**
     - Time axis.





.. include:: ../commontally/samepage.rst
.. include:: ../commontally/file.rst
.. include:: ../commontally/resfile.rst
.. rst-class:: no-caption-number

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

   * - value
     - explanation
   * - **1**
     - [1/cm^2/source]
   * - **2**
     - [1/cm^2/MeV/source]
   * - **3**
     - [1/cm^2/Lethargy/source]
   * - **4**
     - [cm/source]
   * - **11**
     - [1/cm^2/nsec/source]
   * - **12**
     - [1/cm^2/MeV/nsec/source]
   * - **13**
     - [1/cm^2/Lethargy/nsec/source]
   * - **14**
     - [cm/nsec/source]

Lethargy in **unit=3** or **13** is the natural logarithmic unit of energy defined by :math:`\ln(E_{\rm ref}/E)` using a reference energy :math:`E_{\rm ref}` and the particle energy :math:`E`.
Setting these units enables obtaining results in units of Lethargy, which are given as Lethargy widths, :math:`\ln(E_{\rm high}/E_{\rm low})`, for each energy bin in the energy mesh subsection.
Here :math:`E_{\rm high}` and :math:`E_{\rm low}` are the maximum and minimum values of the energy bins, respectively.

Setting **unit=1,2,3,11,12** or **13** produces the mean particle fluence in a specified region calculated from the sum of the track lengths per source divided by the volume of the region.
Note that, for **reg** mesh, the volume in the **[volume]** section must be set.
If this is not done, the particle fluence for **volume=1** [cm^3], that is, the sum of the track lengths per source, is obtained.
For **r-z** and **xyz** meshes, the volume is automatically calculated.
Setting **unit=4** or **14** produces the sum of the track lengths per source.

.. include:: ../commontally/factor.rst
.. include:: ../commontally/title.rst
.. include:: ../commontally/angel.rst
.. include:: ../commontally/sangel.rst
.. include:: ../commontally/2d-type.rst
.. include:: ../commontally/gshow.rst
.. include:: ../commontally/rshow.rst
.. include:: ../commontally/gslat.rst
.. include:: ../commontally/x-txt.rst
.. include:: ../commontally/y-txt.rst
.. include:: ../commontally/z-txt.rst
.. include:: ../commontally/resol.rst
.. include:: ../commontally/width.rst
.. include:: ../commontally/trcl.rst
.. include:: ../commontally/material.rst
.. include:: ../commontally/volmat.rst
.. include:: ../commontally/multiplier.rst
.. include:: ../commontally/epsout.rst
.. include:: ../commontally/bmpout.rst
.. include:: ../commontally/vtkout.rst
.. include:: ../commontally/vtkfmt.rst
.. include:: ../commontally/foamout.rst
.. include:: ../commontally/maxangel.rst
.. include:: ../commontally/ctmin.rst
.. include:: ../commontally/ctmax.rst
.. include:: ../commontally/chmin.rst
.. include:: ../commontally/chmax.rst
.. include:: ../commontally/stdcut.rst
.. include:: ../commontally/iextstat.rst
.. include:: ../commontally/prodenmn.rst
.. include:: ../commontally/prodenmx.rst
.. include:: ../commontally/nbproden.rst