The Mulder library

(MUon fLux unDER)

Description

Mulder is utility library for computing local deformations of the flux of atmospheric due to geophysical features, e.g. taking into account a local topography described by a Digital Elevation Model (DEM).

The master component of Mulder is a fluxmeter, which behaves as a portable probe of the local flux of atmospheric muons. The level of details of fluxmeters is configurable, from a fast continuous approximation delivering an average flux estimate, to a detailed Monte Carlo delivering discrete (weighted) atmospheric muon events (at the observation point).

Note that Mulder only simulates the transport of atmospheric muons, taking into account the local features surrounding the fluxmeter. That is, Mulder does not simulate muons production at height. Instead, a (configurable) reference spectrum of atmospheric muons is used as input, providing the opensky flux, i.e. the flux in the absence of any ground or other obstacles than the Earth atmosphere.

Mulder has a high level Python 3 interface, allowing one to configure and run the core C library (libmulder). The C library can also be used directly, for example as a generator of atmospheric muons for a C/C++ detector simulation. Note however that the C library is bare-bones. High level customization operations are intended to be done from Python. The C library only loads tables at initialisation (e.g. produced from Python), and then it runs (produces muon events) accordingly.

Installation

From PyPI

On Linux, the mulder Python package can be installed with pip as

pip install mulder

Note that Python (3.6, or more) is required (thus you might need to use pip3 instead of pip, depending on your system). The C library is bundled with the Python package. In order to compile C/C++ projects, the mulder executable, shipped with the Python package might be helpful. For example, the following returns installation dependant compilation flags

mulder config --cflags --libs

From source

Mulder source is available from GitHub. Note that the library depends on other projects (git submodules), the like Pumas and Turtle. The complete tree, including dependencies, can be cloned as

git clone --recursive https://github.com/niess/mulder.git

(note the --recursive in the previous command.)

Then, the Python package can be built with the provided Makefile, as

cd mulder
make package

This builds the package locally. Thus, you might also add the corresponding path to your PYTHONPATH, e.g. as following in bash

export PYTHONPATH=$PWD:$PYTHONPATH

The C example(s) can be compiled as

make examples

Usage

The Mulder library is currently in alpha stage. As so, there is no dedicated documentation. However, the Python package has detailed examples. A brief example of usage in C is also provided.

License

The Mulder library is under the GNU LGPLv3 license. See the provided LICENSE and COPYING.LESSER files. The examples however have a separate public domain license allowing them to be copied without any restriction.