Problem statement: The objective is to determine neutron flux due to Galactic Cosmic Rays at the Martian surface for a given location and time.

Steps involved:

1. Configuring the simulation
   1. Since we know the location and time of the point of interest, we obtain the .psf file using the MCD interface script.
   2. The psf file describes the planetary model. In order to be able to use it, we run it through the psf2gdml.py script. This generates for as the corresponding .gdml file which can be used by AtRIS. We make sure that the .gdml file is compliant:
      1. It has a core volume extending from $R_i=0km$ to
   3. We investigate the primary spectrum parameters. We need to consider:

1. we are sampling isotropic particles corresponding to some differential flux J, whereby R_s, A_s are the radius and the surface of the particle source. The particle source is just above the top most atmospheric sheet. We call this the TOA (Top Of Atmosphere). The planet is modeled as a series of homogeneous concentric spherical shells with a solid crust and core.
2. At surface we are generating binary data containing information about secondaries that are passing through the detector sheet interface. This detector sheet has radius R_d and surface A_d.
3. For this particular example, let us say that we are sampling particles from a narrow energy bin between E_1 and E_2 using the provided J.

Now, the actual number N of particles hitting the TOA per second while having an energy between E_1 and E_2 could be huge. We generally do not have the resources to simulate all those particles, so we have to generate a smaller number of particles n=Nf, where f is the factor relating the real number of particles N to the simulated number of particles. $n$ is a known value. We can retrieve it from the simulation data. $n$ however is a count rate and the TOA sheet is in fact a detector. The relation between $J$ and the simulated is linked via the expression provided in the JD Sulivan paper on the topic of the geometric factor and gathering power of particle counters. $n=G \cdot Integral of In my effort to validate AtRIS, I've looked to find as much Earth measurements as possible. It was clear to me that scaling is going to be a non-trivial problem.