Searching for Dark Matter particle signatures with salt minerals as Palaeo-Detectors

The gravitational effects of Dark Matter (DM) as part of the Universe are well studied and can be observed on variable astrophysical and cosmological scales. The particle nature of DM is still under debate. Since the 1980´s, weakly interacting massive particles (WIMPs) are favoured as the objects of DM. In 1995, for the first time, it was suggested using ancient micas as a Palaeo-detector material for WIMPs. Recently, a new publication re-evaluated the possibility of minerals such as Halite as a Palaeo-Detector for WIMPs and concluded that this method may be competitive or even surpassing the sensitivity of direct DM search experiments.

The goal of the proposed research project is to evaluate the potential of Halite (NaCl), as a Palaeo-Detector for WIMP Dark Matter. The detection principle is the identification of WIMP-induced Sodium and Chlorine ion recoil tracks (WRTs) in Halite stored in deep-underground salt deposits. We chose the Permian (260 Myr) salt deposit Unterbreizbach (Thüringen) where the salt is located at a low temperature at a depth between 400m and more than 1000m since more than 80 Myrs.

There are three research aims:

1) Numerical simulation of WRT formation in Halite as a consequence of potential WIMP—nucleus scattering processes.

2) Visualisation of WRTs in Halite by etching and optical microscopy, SEM, and AFM, and UV-C stimulated fluorescence spectroscopy. Ion-irradiation and annealing experiments will allow defining the annealing temperature of tracks.

3) Based on 1) and 2), we plan to derive the discovery and exclusion potential for this DM search method, especially with respect to the discovery potential of direct DM searches.

The expected outcome is the characterization of Halite as a possible Palaeo-detector for WRTs and a thorough assessment of its sensitivity for WIMP DM detection. We intend to submit a full proposal to DFG for funding an extended DM search with Palaeo-Detectors.

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