Some notes on the CORSIKA file generation¶

The generate_simulation function takes in 3 mandatory arguments: the number of the simulation, the type of the primary particle as a string and the number of cores to use for MPI. The first two are simply added to the INP file in the usual way. The third one is factored in to the PARALLEL keyword, which is set equal to the primary energy in GeV divided by the number of cores, divided by a 100.

The zenith, azimuth and primary energy are all optional arguments to the function. If they are not provided, the function will randomly sample these values from some distributions. For this, three other functions are defined in the same module: sample_zenith_angle, sample_azimuth_angle and sample_primary_energy. These are equipped with same ranges wherein to sample. For the zenith angle, the range is between 0 and 90 degrees. For the azimuth angle, the range is between 0 and 360 degrees. For the primary energy, the range is between \(10^{8}\) and \(10^{10}\) GeV. If you wish to also randomly select values for these parameters but within other ranges, you can these directly when calling generate_simulation.

Other variables controlling the simulation are the magnetic field, the atmospheric model to use and the thinning setting. The last two are an integer and a float respectively, as usual for a CORSIKA input file. For the magnetic field you can either pass the vector itself (in internal units of course) or a string. The string should be the name of an experimental site whose magnetic field vector is part of the radiotools package. Note that after retrieving the magnetic field vector from radiotools, the x-component (corresponding to the East-West direction) is set to zero, to ensure the antennas are always placed on the shower plane axes.

Lastly, there are the variables controlling the antenna configuration. First of all, we have the thickness of the atmospheric slices. Then there is also the core position to use, which also defines the observation level of the simulation. Lastly the radii parameter is a list of floats, which are interpreted depending on the value of the cherenkov parameter.

If the cherenkov parameter is set to False, which is the default, the radii are taken to be the distances in the shower plane from the antennas to the core, on one arm. If not provided, this defaults to a list of 26 distances which run from 1.5m to 500m. In this case, every slice will have the same physical antennas on the ground.

This is different from when cherenkov is set to True. In this case, the radii are interpreted as viewing angles for every slice, where the viewing angle is a fraction of the slice Cherenkov angle. Typically, the radii in this case are numbers between 0.01 and 5. As the Cherenkov angle is different in every slice, this option will result in a different set of antenna locations for each slice. This option is useful for testing and validating the template synthesis algorithm, as you can readily simulate the necessary antennas to recalculate the spectral parameters.