Noise Temperature Measurements for Axion Haloscope Experiments at IBS/CAPP

The axion was first introduced as a consequence of the Peccei-Quinn mechanism to solve the CP problem in strong interactions of particle physics and is a well-motivated cold dark matter candidate. This particle is expected to interact extremely weakly with matter, and its mass is expected to lie in $$\upmu$$ eV range with the corresponding frequency roughly in GHz range. In 1983, P. Sikivie proposed a detection scheme, so-called axion haloscope, where axions resonantly convert to photons in a tunable microwave cavity permeated by a strong magnetic field. A major source of the experimental noise is attributed to added noise by RF amplifiers, and thus, precise understanding of amplifiers’ noise is of importance. We present the measurements of noise temperatures of various low-noise amplifiers broadly used for axion dark matter searches.