A Cosmic Ray Air Shower Creator for the Antarctic Impulsive Transient Antenna (ANITA).

Anchor (ANITA Cosmic-Ray Shower Creator) is a utility to automate the generation of cosmic ray shower templates for the Antarctic Impulsive Transient Antenna (ANITA). Anchor handles the compilation, event setup, and Aires configuration necessary for all three primary classes of ANITA events (reflected, stratospheric, and upgoing events). Anchor also supports direct downgoing air showers (as would be used for ground radio arrays).

Anchor does not include the various ZHAireS versions needed to run the supported simulations (it is a high-level wrapper). If you are member of the ANITA collaboration, contact @rprechelt on Slack for all the files you need. Otherwise, you will need to contact the authors of ZHAireS (anchor currently uses the following ZHAireS versions: 28r18c-loopfresnel, 28r18c-Upgoing, 28r21-ANITA-reflected, and 28r24-RASPASS). See the Aires install script for details.

To install anchor, you will need git and Python >= 3.6. All three should be available in the package manager of any modern OS. It is tested on macOS 10.14, ubuntu 18.04, ubuntu 16.04, Fedora 29, and Fedora 30.

The below instructions are assuming that python refers to Python 3.*. If python still refers to a decrepit Python 2.*, please replace python with python3 and pip with pip3.

Before installing anchor, you will need to set the AIRES_RUN_DIR environment variable telling zhaires.py (the low-level Aires wrapper package) where to store the Aires/ZHAireS output files. Each simulated shower is created in its own directory under AIRES_RUN_DIR with the name of the Aires task.

> export AIRES_RUN_DIR=<path to directory with decent storage capacity>

This should be added to your .{bash,zsh,fish,tcsh,c}rc file if you plan on regularly using anchor or zhaires.py.

The recommended method of installation is to first clone the package

> git clone https://github.com/rprechelt/anchor

and then change into the cloned directory and install using pip

> cd anchor
> pip install --user -e .

We now need to install the various Aires/ZHAireS binaries that anchor uses to perform the shower simulations. Change into the anchor/aires directory. You will need to ensure that the following tree structure is recreated (if you are a member of ANITA, contact @rprechelt).

> cd anchor/aires/
> ls
    sources/
> ls sources/
    Aires.2-8-4a.tar.gz
    ZHAireS-betav28r18c-loopfresnel.tar
    ZHAireS-betav28r18c-Upgoing.tar
    ZHAireS-betav28r21-ANITA-reflected-beta0.2-Frcoeffs.tar
    ZHAireS-betav28r24-RASPASS.tar

Once all the above tar-balls are in place, you can then run

> ./setup.sh

from the anchor/aires directory. This will compile all four versions of ZHAireS (this may take ~5 minutes).

You should then make sure that the installation was successful by trying to import anchor

> python -c 'import anchor'

If you wish to develop new features in anchor, you will also need to install some additional dependencies so you can run our unit tests

> pip install --user -e .[test]

Once that is completed, you can run the unit tests directory from the anchor directory

> python -m pytest tests

anchor includes a script to launch simulations directly from your shell:

anchor -h

will print a help message detailing the various configuration parameters that are available.

All showers will load the defaults/common_default.inp file in the anchor directory. You should inspect this file to see the current defaults (which are chosen based on ANITA.) If you wish to run showers for another experiment, these will most likely need to be changed.

If you want to start simulations from a Python script, you can use the create_shower function

import anchor

# create the simulation
sim = anchor.create_shower(
    "my_simulation",
    "proton",
    18.0,
    30.0,
    180.0,
    -90.0,
    0.0,
    ground=2.5,
    thinning=1e-5,
    restart=True,
    program="/path/to/my/aires/installation/bin/Aires"
)

# run the simulation
sim.run()

will create a simulation called my_simulation of a 10^{18} eV proton with a 30 degree zenith angle, 180 degree azimuth angle, at a location of latitude -90 degrees, longitude 0 degrees, with a ground altitude of 2.5 km, and a thinning of 1e-5.

If you wish to use the Aires executables provided by anchor, two courtesy functions are provided

# create a direct shower
sim = anchor.create_direct(...)  # same arguments as create_shower

# and run it
sim.run()

# create a reflected shower
sim = anchor.create_reflected(...)  # same arguments as create_shower

# and run it
sim.run()

that allow for easily running showers using the built-in Aires versions - these also load either defaults/direct_default.inp or defaults/reflected_default.inp before applying any user arguments.