Obscura: A modular C++ tool and library for the direct detection of (sub-GeV) dark matter via nuclear and electron recoils

Timon Emken

doi:10.21105/joss.03725

Abstract

For the interpretation of past and future direct searches for dark matter (DM) particles, it is important to be able to provide accurate predictions for event rates and spectra under a variety of possible and viable assumptions in a computationally efficient way. While there exists a few tools to compute DM induced nuclear recoil spectra, 'obscura' is not limited to nuclear targets. Instead its main focus lies on sub-GeV DM searches probing electron recoils which typically requires methods from atomic and condensed matter physics. In the context of sub-GeV DM searches, new ideas such as target materials or detection techniques are being proposed regularly, and the theoretical modelling of these are getting improved continuously. At the same time, currently running experiments continue to publish their results and analyses, setting increasingly strict bounds on the DM parameter space. In such a dynamic field, 'obscura' can be an invaluable tool due to its high level of adaptability and facilitate and accelerate the development of new, reliable research software for the preparation of a DM discovery in the hopefully near future.

Highlights

One of the leading hypothesis is that dark matter (DM) is made up of one or more new particles and that galaxies such as our Milky Way are embedded in gigantic haloes of these as of yet undetected particles
Direct detection experiments search for these kind of interactions and aim to observe DM events within a detector caused by an interaction with target nuclei (Drukier et al, 1986; Goodman & Witten, 1985; Wasserman, 1986) or electrons (Essig et al, 2012; Kopp et al, 2009)
In order to interpret the outcome of direct detection experiments, we need to make predictions for the expected events caused by the incoming DM particles

Summary

The observation of a large number of gravitational anomalies on astrophysical and cosmological scales have convinced us that the majority of matter in the Universe is invisible (Bertone et al, 2005; Bertone & Tait, 2018). Direct detection experiments search for these kind of interactions and aim to observe DM events within a detector caused by an interaction with target nuclei (Drukier et al, 1986; Goodman & Witten, 1985; Wasserman, 1986) or electrons (Essig et al, 2012; Kopp et al, 2009). In order to interpret the outcome of direct detection experiments, we need to make predictions for the expected events caused by the incoming DM particles In all cases, this requires making a number of assumptions about the possible particle attributes of DM (e.g., mass and interaction strength) and the properties of the galactic DM halo (e.g. the local DM density and their energy distribution) (Del Nobile, 2021; Lewin & Smith, 1996). For more details on obscura and its implementation in C++, we refer to the documentation

The modular structure of direct detection computations

DM mass mDM and the differential

Statement of need