1. Getting started

Installation

Before building obscura, there are a few libraries that need to be installed.

Dependencies

1. boost

To install boost on a Mac, we can use homebrew

brew install boost

On Linux machines, run:

sudo apt-get update && sudo apt-get install -yq libboost-all-dev

2. libconfig

To install boost on a Mac, we can use homebrew

brew install libconfig

On Linux machines, you can build libconfig via:

wget https://hyperrealm.github.io/libconfig/dist/libconfig-1.7.2.tar.gz
tar -xvzf libconfig-1.7.2.tar.gz
pushd libconfig-1.7.2
./configure
make
sudo make install
popd

3. libphysica

libphysica does not need to be installed. It will be downloaded and compiled during the CMake build.

Download & Build

The obscura source code can be downloaded by cloning this git repository:

git clone https://github.com/temken/obscura.git
cd obscura

The code is compiled and the executable and library is built by CMake. To build run the following commands from the repository’s root folder.:

cmake -E make_directory build
cd build
cmake -DCMAKE_BUILD_TYPE=Release -DCODE_COVERAGE=OFF ..
cmake --build . --config Release
cmake --install .

If everything worked well, the executable and library file are created as:

bin/obscura
lib/libobscura.a

Using obscura as a tool

Obscura can be used as a tool and builds an executable which can be run from /bin/ via:

./obscura config.cfg

As can be seen in the /src/main.cpp file, this script computes direct detection limits and saves them in the /results/ folder. The specifications of the exclusion limits (DM physics and halo model, statistics, experiment, mass range,…) are defined in a configuration file, in this case config.cfg. For the handling of configuration files, obscura relies on libconfig.

The configuration file

The configuration file contains all input parameters necessary to define the various obscura models.

Warning

The import of these parameters via libconfig is very case-sensitive. A float parameter has to be set to e.g. 1.0, and not just 1.

The full configuration file
//obscura - Configuration File

//ID
     ID              =       "test";

//Dark matter particle
     DM_mass                 =       0.1;            // in GeV
     DM_spin                 =       0.5;
     DM_fraction             =       1.0;            // the DM particle's fractional abundance (set to 1.0 for 100%)
     DM_light                =       false;          // Options: true or false. low mass mode

     DM_interaction          =       "SI";           // Options: "SI" or "SD"

     DM_isospin_conserved            =       true;           // only relevant for SI and SD
     DM_relative_couplings           =       (1.0, 0.0); //relation between proton (left) and neutron (right) couplings.
                                                                                             //only relevant if 'DM_isospin_conserved' is false.
     DM_cross_section_nucleon        =       1.0e-36;        //in cm^2
     DM_cross_section_electron       =       1.0e-36;        //in cm^2 (only relevant for SI and SD)
     DM_form_factor          =       "Contact";      // Options: "Contact", "Electric-Dipole", "Long-Range", "General"
                                                                                             //(only relevant for SI)
     DM_mediator_mass        =       0.0;            // in MeV (only relevant if 'DM_form_factor' is "General")

//Dark matter distribution
     DM_distribution         =       "SHM";          //Options: "SHM", "SHM++", "File"
     DM_local_density        =       0.4;            //in GeV / cm^3

     //Options for "SHM" and "SHM++"
             SHM_v0          =       220.0;                          //in km/sec
             SHM_vObserver   =       (0.0, 232.0, 0.0);      //in km/sec
             SHM_vEscape     =       544.0;                          //in km/sec
     //Options for "SHM++"
             SHMpp_eta       =       0.2;
             SHMpp_beta      =       0.9;
     //Options for "File" (The file has to be a 2-column table of format v[km/sec] :: f(v) [sec/km])
             file_path  = "DM_Speed_PDF.txt";

//Dark matter detection experiment
     DD_experiment   =       "Electron recoil";      //Options for nuclear recoils: "Nuclear recoil", "DAMIC_N_2011", "XENON1T_N_2017", "CRESST-II","CRESST-III", "CRESST-surface"
                                                     //Options for electron recoils: "Semiconductor","protoSENSEI@MINOS","protoSENSEI@surface", "SENSEI@MINOS", "CDMS-HVeV_2018", "CDMS-HVeV_2020", "Electron recoil", "XENON10_S2", "XENON100_S2", "XENON1T_S2", "DarkSide-50_S2"

     //Options for user-defined experiments ("Nuclear recoil", "Electron recoil", and "Semiconductor")
       //General
       DD_exposure           =       1.0;    //in kg years
       DD_efficiency                 =       1.0;    //flat efficiency
       DD_observed_events    =       0;              //observed signal events
       DD_expected_background        =       0.0;    //expected background events

       //Specific options for "Nuclear recoil"
       DD_targets_nuclear    =       (
                                     (4.0, 8),
                                     (1.0, 20),
                                     (1.0, 74)
                             );                              // Nuclear targets defined by atom ratio/abundances and Z
       DD_threshold_nuclear    =     4.0;    //in keV
       DD_Emax_nuclear         =     40.0;   //in keV
       DD_energy_resolution    =     0.0;    //in keV

       //Specific options for "Electron recoil" and "Semiconductor:
       DD_target_electron    =       "Xe";   //Options for "Electron recoil":        "Xe", "Ar"
                                                                     //Options for "Semiconductor":  "Si", "Ge"
       DD_threshold_electron =       4;              //In number of electrons or electron hole pairs.

//Computation of exclusion limits
     constraints_certainty   =       0.95;   //Certainty level
     constraints_mass_min    =       0.02;   //in GeV
     constraints_mass_max    =       1.0;    //in GeV
     constraints_masses      =       10;

Using obscura as a library

If we want to use obscura functions in an external code, we can do so and import it as a library. We recommend to do this inside your CMake build, where obscura can be downloaded, built, included, and linked automatically during the build of your code.

As an instructional example this repository contains a C++ project template built with CMake that imports and uses the obscura library.