A New Method for Detecting Axion With Cylindrical Superconductor

We propose a method for searching dark matter axion in axion-photon conversion. We consider a superconductor of cylindrical shape under strong magnetic field. The dark matter axion generates oscillating electric field which induces oscillating superconducting current in the surface of the superconductor. The current gives rise to dipole radiation with the frequency $m_a/2\pi$ given by axion mass $m_a$. We show that the radiation flux generated by the current is of the order of $10^{-18}$W under magnetic field $\sim 3$T in the case of radius $\sim 1$cm and length $\sim 10$cm of the cylindrical superconductor. %The superconducting current flows in the surface to the depth $\lambda\simeq 5\times 10^{-6}$cm. The large amount of the radiation flux arises because Cooper pairs with large number density ( $\sim 10^{22}/\rm cm^{3}$ ) is present in the superconductor. With the high detection sensitivity, we can simultaneously search wide bandwidth of the radio frequency with existing radio telescope.