Noise Temperature Measurements for Axion Haloscope Experiments at IBS/CAPP
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Noise Temperature Measurements for Axion Haloscope Experiments at IBS/CAPP S. W. Youn1 · E. Sala1 · J. Jeong1 · J. Kim1 · Y. K. Semertzidis1 Received: 30 August 2019 / Accepted: 23 July 2020 / Published online: 7 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract 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 wellmotivated cold dark matter candidate. This particle is expected to interact extremely weakly with matter, and its mass is expected to lie in μ 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. Keywords Axion · Haloscope · Noise measurement · RF amplifier
1 Motivation The strong CP problem refers to the discrepancy between the experimental results suggest a conservation of the Charge-Parity symmetry in strong interactions and the predictions requiring a violating term in the Lagrangian [1–3]. In 1977, R. Peccei and H. Quinn proposed a mechanism to solve the problem with the introduction of a global symmetry whose spontaneous breaking is associated with a Goldstone boson, named axion. The value of the axion mass is, however, arbitrary, but several ranges have been ruled out by cosmological constraints and astrophysical observations, indicating that its mass would fall in the μeV–meV range which corresponds to about 1–1000 GHz in frequency range. These properties make the axion an excellent cold dark matter candidate [4]. * E. Sala [email protected] 1
Center for Axion and Precision Physics Research, Institute for Basic Science, Daejeon 34051, South Korea
1Vol:.(1234567890) 3
Journal of Low Temperature Physics (2020) 200:472–478
473
1.1 Searching for Axion at CAPP A fast growing interest has brought several collaborations to search for axions. Among these, the Center for Axion and Precision Physics Research (CAPP) of the Institute for Basic Science (IBS) in South Korea was founded in 2013 aiming to contribute to axion physics with several experiments, most of them exploiting the haloscope technique. By now the center has built a facility equipped with dilution refrigerators and superconducting magnets which are used in parallel to search for axions in different mass ranges. At the same time, R&D projects are ongoing to enhance the sensitivity of the experiments by improving the cavity quality factor (Q) and cavity design in addition to developing low-noise high-gain amplifiers [5]. 1.2 Axion Haloscope and System Noise In 1983, P. Sikivie proposed a method to detect axion
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