February 26, 2019
If darkish matter interactions occurred inside historic rocks, they may have left detectable traces within the rocks’ crystal construction.
The rocks beneath our toes might include vestiges—within the type of nanometer-wide tracks—of previous darkish matter interactions. Earlier searches for these so-called darkish matter fossils have come up empty, however a crew of researchers from Sweden and Poland believes that current advances in materials evaluation strategies warrant a brand new marketing campaign to “dig” them up. The crew predicts that sure minerals from deep drill cores may present indicators of darkish matter with a sensitivity surpassing that of present search strategies.
Fossil observe identification was initially developed to check nuclear fission in previous rocks. When a high-energy fission product barrels by the crystal construction, it leaves an amorphous observe that may be a few nanometers huge and some micrometers lengthy. Darkish matter particles may produce comparable—however shorter—tracks by collisions with nuclei, however a search revealed in 1995 utilizing atomic pressure microscopy discovered no such signatures.
For this up to date research, the researchers suggest utilizing present-day strategies, corresponding to helium-ion beam microscopy and small-angle x-ray scattering, to instantly map the whole quantity of a gram’s price of rock with nanometer decision. Such a feat was beforehand unimaginable. They recommend acquiring samples from low-radioactivity minerals in 10-km-deep boreholes, which ought to include fewer tracks from different particles like cosmic rays.
The crew estimates cubic centimeter of historic rock may maintain lots of to hundreds of dark-matter-induced tracks, which, they are saying, could be identifiable by their distinctive distribution of observe lengths. Their calculations additionally recommend that the sensitivity of a gram-sized “paleo-detector”—whose rocky materials has been “looking out” for darkish matter for roughly a billion years—could possibly be better than present ton-sized detectors which have solely been operating for a couple of years.
This analysis is revealed in Bodily Evaluation D.
Michael Schirber is a Corresponding Editor for Physics based mostly in Lyon, France.
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