.. _[t-heat]:

[ T-Heat ] section
==================================================

This tally can be used to obtain deposition energies (heat) in certain regions using kerma approximation.
However, the function to calculate deposition energy using kerma approximation was also implemented in ``[t-deposit]`` after version 3.05, and thus, we do not recommend to use ``[t-heat]`` after that version.

Although the deposition energy from neutrons is zero for **e-mode** >= 1, it can be calculated instead from the energy loss of all charged particles and nuclei.
The deposition energy from photons is also usually obtained from kerma factors.
For **electron=1** with electron transport, photon kerma factors are not used; instead, deposition energies are obtained from the energy loss of electrons.

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.. list-table:: **mesh**
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   * - value
     - explanation
   * - **reg, r-z, xyz**
     - Mesh type.
       A mesh type subsection is required below this option.

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.. list-table:: **axis**
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   * - value
     - explanation
   * - **reg, x, y, z, r**
     - x axis value of output data.
   * - **xy, yz, xz, rz**
     - 2-dimensional.

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.. list-table:: **output**
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   * - value
     - explanation
   * - **heat**
     - total:
       Total deposit energy.
       leakage:
       Kinetic energy of particles entering the outer void.
       recoil:
       Kinetic energy of residual nuclei when cut-off energy **emin(15-19)** is set.
       ionization:
       Energy deposited by energy-loss of charged particles.
       low neutron:
       Energy deposit calculated by neutron kerma factors.
       photon:
       Energy deposit by kerma factors.
       If **electron=1**, this means contributions of electrons below cut-off energy.
       others:
       Excitation energy of residual nuclei.
       Setting **igamma=1** makes this value 0 owing to photon emission.
   * - **simple**
     - total:
       Total deposit energy.
       leakage:
       Kinetic energy of particles entering the outer void.
       recoil:
       Kinetic energy of residual nuclei when cut-off energy **emin(15-19)** is set.
       ionization:
       Energy deposited by energy-loss of charged particles.
       low neutron:
       Energy deposit calculated by neutron kerma factors.
       photon:
       Energy deposit by kerma factors.
       If **electron=1**, this means contributions of electrons below cut-off energy.
       others:
       Excitation energy of residual nuclei.
       Setting **igamma=1** makes this value 0 owing to photon emission.
   * - **all**
     - In addition to the above parameters;
       contributions of :math:`d`, :math:`t`, :math:`^3\mathrm{He}`, :math:`\alpha`, and residual nuclei to recoil.
       Contributions of :math:`p`, :math:`\pi^+`, :math:`\pi^-`, and others to ionization are output.
       Contributions of particles specified by **part** are output, but not plotted in the eps file.
       stopped particle:
       Kinetic energy of stopped proton, neutron, :math:`\pi^+`, :math:`\pi^-`, and other particles in materials.
       Contributions of particles specified by **part** are output, but not plotted in the eps file.
       others:
       Remaining excitation energy and fission components.
       When **axis** is 2-dimensional, **all** is the same as **simple**.
       Only total, recoil, ionization, low neutron, electron, and others are output.

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.. list-table:: **unit**
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   * - value
     - explanation
   * - **0, 1, 2**
     - 0: [Gy/source]
       1: [MeV/cm^3/source]
       2: [MeV/source]

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Generally speaking, heat is energy produced by the ionization of charged particles.
However, in the transport simulation, transport is stopped below the set particle cut-off energy.
In this case, additional components of heat, including recoil, stopped particle, and others, will be output to the heat tally.
These components may change as the parameters of the transport are changed.

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.. list-table:: **electron**
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   * - value
     - explanation
   * - **0** (default), **1**
     - Electron contribution options.
       0: using photon kerma factors.
       Electron and positron should not be transported, otherwise their deposition energies are double-counted.
       1: calculating by ionization loss.
       Electron and positron transport are required.

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When **unit=0** with **output=dose**, results can be obtained in units of [Gy/source].
When **mesh=reg**, the volumes of each cell should be defined in **[volume]** or set as **volume** parameters of **[t-deposit]**.
Because absorbed dose is an intensive variable, PHITS does not output a sum over in output files for **unit=0**.
Note that, in a region including more than two materials, the dose in the region does not equal the average value of the region.
For example, when there are two materials with masses :math:`M_1` and :math:`M_2`, and absorption energies :math:`E_1` and :math:`E_2`, respectively, PHITS gives :math:`\frac{E_1}{M_1}\frac{V_1}{V_1+V_2}+\frac{E_2}{M_2}\frac{V_2}{V_1+V_2}` in this tally, even though its average dose is :math:`\frac{E_1+E_2}{M_1+M_2}`.
Here, :math:`V_1` and :math:`V_2` are volumes of the two materials.

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