Detectable Electric Current induced by Dark Matter Axion in a Conductor

Abstract

We propose a way of detecting dark matter axion by using two slabs of conductor. The flat surfaces are put to meet face to face so that they are parallel to each other. External magnetic field B parallel to the surfaces is impressed. Radiations converted from the axion arise between two slabs. When we tune the spacing l between two surfaces such as l = π/ma with axion mass ma, a resonance occurs so that the radiations become strong. Furthermore, electric current flowing on the surface of the slabs is enhanced. We show that the electric current is large enough to be detectable at the resonance. It reaches 0.7×10 −9 A(10 −5 eV/ma) 1/2 (B/5T)(L/10cm)(σ/3.3×10 7 eV), using 6N copper of the square slab with side length L and high electrical conductivity σ at temperature T ∼ 1K. The power of the Joule heating is 0.3 × 10 −22 W(B/5T) 2 (10 −5 eV/ma) 1/2 (L/10cm) 2 (σ/3.3 × 10 7 eV). When we amplify the power using LC circuit with Q factor, the signal to noise ratio is 4.5 × 10 4 (Q/10 6 )(B/5T) 2 (t obs /1 sec) 1/2 (10 −5 eV/ma)(L/10cm) 2 (σ/3.3 × 10 7 eV) with t obs observational time.

Radiation Burst by Axion Star Collision with Star in the Andromeda Galaxy

“…The axion is also a promising candidate of dark matter in the universe. Therefore, its detection [2][3][4][5][6][7][8][9][10][11] is urgent issue for exploring beyond standard model. Such an axion is called as QCD axion, which was originally introduced to solve strong CP problem.…”