9 December 2013
Dark matter particles from the galactic halo that hit the earth may produce a small measurable resonance signal in Josephson junctions --- and the signal can be used to estimate their mass and density near the earth. This is the main conclusion of a new paper published by Christian Beck, Professor of Applied Mathematics in the School of Mathematical Sciences, Queen Mary University of London, in the journal Phys. Rev. Lett. in December 2013.
Most of the matter contents of the universe is in the form of unknown particles, so-called dark matter, and a couple of experimental searches are going on to find these particles by experiments on the Earth. Beck's idea is applicable for a particular type of dark matter particles, so-called axions. Axions have a very small mass and are extremely cold. He suggests to use Josephson junctions as suitable detectors:
These are superconducting devices with a small region of normal metal inbetween the superconductors. An experimental group in Grenoble has seen a signal that is consistent with Beck's theory.