The universe is believed to be permeated by an unknown substance named Dark Matter because it is not visible, interacting extremely weakly with ordinary matter while revealing its existence only through gravitational effects. One of the leading candidates is the axion particle, a pseudo-scalar, similar to the scalar Higgs particle, but much lighter in mass. Axions were also invented to cure a major theoretical defect in strong interactions, that of time reversal violation. Even though the theory of Quantum Chromo Dynamics (QCD, i.e., the theory describing Strong Interactions) works very well, its prediction on time reversal violation is not followed by ten orders of magnitude, as evidenced by the absence of CP-violation in the neutron particle. Axions oscillate at one, albeit unknown, frequency and softly mix with photons whenever a magnetic field is present creating a very faint oscillatory electric field. A 10T magnetic field would generate an oscillatory electric field of order 1pV/m, which in the presence of a high-quality resonator can be significantly enhanced when its frequency coincides with the resonator frequency. Since we don’t know the axion frequency we need to scan all possible frequencies, effectively having to call all the numbers in a large volume phone-book one number at a time. Each phone call would have to last more than 1 minute to have a chance of finding out whether that number is the right one. The scanning rate goes as the magnetic field strength to the fourth power times the resonator volume squared. The axions have eluded discovery for more than thirty-five years since they were conceived to be the dark matter, but recent progress in several technological fronts, one of the most important ones being in superconducting magnet technology, give us renewed hope.
There is a revolution in the superconducting magnet technology: High-Temperature Superconducting (HTS) and Low-Temperature Superconducting (LTS) cables based on Nb3Sn are becoming more common. I will describe how we at the Center for Axion and Precision Physics Research are planning to use the current technology of HTS and LTS from pioneering institutions around the world to finally pin down and discover the axion frequency. Once the frequency is found, then many institutions around the world will be able to launch an axion dark matter experiment and the era of axion astrophysics will be born. The superconducting magnet technology is a fundamental aspect of this plan.
Learn how the Center for Axion and Precision Physics Research plans to use the current technology of HTS & LTS from pioneering institutions around the world to finally pin down and discover the axion frequency.