Nuclear Tracks from Cold Dark Matter Interactions in Mineral Crystals: a Computational Study

Recoiling nuclei from Cold Dark Matter (CDM) elastic scattering interactions with the constituent elements of some minerals may produce etchable damage tracks in the crystal structure. Present calculations show that in muscovite mica, CDM tracks from recoiling potassium atoms could be readily distinguished from others due to alpha-decays in the uranium and thorium chains. Under favorable conditions, this technique could greatly improve the existing limits on Weakly Interacting Massive Particles as the constituents of the galactic halo. Numerous Dark Matter candidates have been proposed, that could constitute the approximately 90% of the universe unobservable by conventional astronomy. Ample literature exists, covering various members of the candidate arena [1,2]. Experimental searches are currently operational or under development [1]; Baryonic Dark Matter (BDM), in the form of Massive Astrophysical Compact Halo Objects (MACHOs) can account for part of the galactic dark halo. The detection of MACHOs (in the range 10 −7 to 10-1 solar masses) may be possible by means of gravitational micro-lensing. Preliminary reports [3] indicate that such events may have been observed. While the data at hand are still inconclusive, there seems to be an initial agreement between the frequency of these observations and what is expected from an important contribution of BDM to the halo mass. Nevertheless, even if BDM in this form has been observed, it cannot be the single source of dark matter in the Universe without contradicting the predictions of Primordial Nucleosynthesis. Hot Dark Matter, light relativistic neutrinos, is another possibility probed by experiments designed to search for a finite neutrino mass (m ν ≈ few eV' s). Probably the most populated candidate group is that of Cold Dark Matter (CDM), consisting of heavy, non-relativistic particles, extending over a large range of possible masses and coupling constants. As a subdivision of the CDM category, Weakly Interacting Massive Particles (WIMPs) comprise some of the most interesting candidates. The theoretical justification for the existence of WIMPs stems from extensions of the Standard Model of the electro-weak interaction, and in some cases, have the added attraction of having been initially postulated to solve theoretical problems unrelated to that of Dark Matter, as it is the case for the Lightest Supersymmetric Partner (LSP, generally considered to be a neutralino, product of the predictions of the Minimal Supersymmetric Standard Model). An important reason why WIMPs have become so prevalent in the dark matter theater is their natural ability to account for …