=== - Planet Specification Format (PSF) ===

{{atris:psf.png|The planet specification format (PSF)}}

The idea is to define the atmosphere specification in a robust way, which is both future proof and misinterpretation-proof. The main characteristics of the format are:

  * The format specifies the atmosphere as **one sheet per line**. The number of lines specifies the number of atmospheric sheets.
  * The format also includes a polar and azimuth angle variability to make it future proof.
  * Please don't limit the number precision and use scientific notation!
  * Sum over all mass fractions is equal to 1.00.
  * The above does not include the soil column. The soil column should be set to one for the soil and crust volumes. 
  * The sensitive detector ID (SDID) is an integer quantity. 0 and 1 are reserved for core and crust.
  * Please always include a core and a crust
  * The atmosphere should be built from the bottom up, starting with the SDID 2.
  * Don't skip SDIDs.
  * Header: The header is ment to specify the soil composition(column 10) and also to name the material whose contribution is specified in one of the columns designated with //11,12,13//. Example: <code> #578Si380Al242Fe CO_2 N Ar </code> Note: <color red> you can use materials available in the Geant4 NIST material {{http://geant4-userdoc.web.cern.ch/geant4-userdoc/UsersGuides/ForApplicationDeveloper/html/Appendix/materialNames.html#g4matrdb|database}}. Leave out the prefix "G4_$. If your gas molecule is not available, you can specify it as an artificial mixture. For example, SO2 would be 50.05% Sulfur and 49.95% Oxygen (in terms of mass fraction). The error of this approximation is discussed [[atris:error_of_mixed_materials|here]].</color>
  * Unlimited header lines are possible, as long as they start with "#", they will not produce an error in the data analysis
  * The first entry tells AtRIS that the soil is 578 parts Si, 380 parts Al, 242 parts Fe.
  * The following entries specify what materials do the individual columns specify. 
  * Example:

^ Column nr  ^ Name         ^ Long Name                        ^ Unit                     ^ Range         | Type, Notation  |
| 0          | alt_low      | altitude at bottom of the layer  | km                       | 0-            | %12e            |
| 1          | alt_high     | altitude at top of the layer     | km                       | 0-            | %12e            |
| 2          | phi_low      | azimuth angle start              | rad                      | 0-6.2831853   | %12e            |
| 3          | phi_high     | azimuth angle stop               | rad                      | 0-6.2831853   | %12e            |
| 4          | theta_low    | polar angle start                | rad                      | 0-3.14159265  | %12e            |
| 5          | theta_high   | polar angle stop                 | rad                      | 0-3.14159265  | %12e            |
| 6          | SDID         | (0=core,1=crust), 2,3,...        |                          | 0-666         | %4i             |
| 7          | Temperature  |                                  | K                        | 0-            | %12e            |
| 8          | Density      |                                  | $\rm{g}/\rm{cm}^3$       | 0-            | %12e            |
| 9          | Pressure     |                                  | hPa                      | 0-            | %12e            |
| 10         | Soil         | Mass fraction of soil            | $\%\,(\rm{kg}/\rm{kg})$  | 0-1.0         | %12e            |
| 11         | $\rm{CO_2}$  | Mass fraction of CO2             | $\%\,(\rm{kg}/\rm{kg})$  | 0-1.0         | %12e            |
| 12         | $\rm{N_2}$   | Mass fraction of N2              | $\%\,(\rm{kg}/\rm{kg})$  | 0-1.0         | %12e            |
| 13         | $\rm{Ar}$    | Mass fraction of Ar              | $\%\,(\rm{kg}/\rm{kg})$  | 0-1.0         | %12e            |

  * In this example, we have:
    * first 6 columns defining the geometry of the planet element
    * one column holding the SDID
    * 3 columns containing the macroscopic quantities.
    * 1 column for soil material specification
    * 5 columns containing gasses from G4's NIST database
  * Since the angular quantities are stated in terms of radians, a spherical shell should set theta_low=0, theta_high=3.14159265, phi_low=0, phi_high=6.2831853
  * All altitudes should be measured from the center of the planet. This is important when scaling the simulated flux with a real flux. Therefore, the core volume should have alt_low=0km, alt_mid=6365.0km
  * The user should ensure that there are no gaps between the volume elements of the planet.
  * Particles are not tracked within the core. 
  * Shell particles are tracked in order to allow for surface albedo particles. Reducing the shell thickness to a "good-enough" minimum improves performance. I use 20m. 

== Examples files ==
  * Example {{atris:one.psf}} and the resulting {{atris:one.gdml}} file - this file has been obtained using the [[atris:nrlmsise00]] interface.
  * Example {{atris:two.psf}} and the resulting {{atris:two.gdml}} file - this file is used to illustrate the differences between Geant4 NIST materials and //material mixtures//. See [[atris:error_of_mixed_materials]] for more info.
  * Example {{atris:icru.psf}} and the resulting {{atris:icru.gdml}} file - this file has been used to simulate the effects that radiation has on an ICRU water {{https://www.iaea.org/ns/tutorials/regcontrol/intro/glossaryi.htm|ICRU spherical phantom}} with shielding applications. 

The gdml files are created using the //psf2gdml.py// script. Note that the .psf files offers advantages for human use, since it is much easier to read. [(The specified number format has not been used, since we wanted the examples to be illustrative of the general features.)]