Revisiting the detection rate for axion haloscopes

The cavity haloscope has been employed to detect microwave photons resonantly converted from invisible cosmic axions under a strong magnetic field. In this scheme, the axion-photon conversion power has been formulated to be valid for certain conditions, either $Q_{cavity}\ll Q_{\rm axion}$ or $Q_{cavity} \gg Q_{axion}$. This remedy, however, fails when these two quantities are comparable to each other. Furthermore, the noise power flow has been treated independently of the impedance mismatch of the system, which could give rise to misleading estimates of the experimental sensitivity. We revisit the analytical approaches to derive a general description of the signal and noise power. We also optimize the coupling strength of a receiver to yield the maximal sensitivity for axion search experiments.Comment: 15 pages, 7 figure

Fabrication of polyimide nanotubes and carbon nanotubes containing magnetic iron oxide in confinement

Polyimide nanotubes with tunable wall thickness were fabricated by a precursor impregnation method using an AAO template, and carbon nanotubes containing magnetic iron oxide were obtained using ferric chloride-embedded polyimide precursor by a carbonization process.This work was supported by Korea Science and Engineering Foundation through the Hyperstructured Organic Materials Research Center

Search for the Sagittarius Tidal Stream of Axion Dark Matter around 4.55 μ\mueV

We report the first search for the Sagittarius tidal stream of axion dark matter around 4.55 $\mu$eV using CAPP-12TB haloscope data acquired in March of 2022. Our result excluded the Sagittarius tidal stream of Dine-Fischler-Srednicki-Zhitnitskii and Kim-Shifman-Vainshtein-Zakharov axion dark matter densities of $\rho_a\gtrsim0.184$ and $\gtrsim0.025$ GeV/cm$^{3}$, respectively, over a mass range from 4.51 to 4.59 $\mu$eV at a 90% confidence level.Comment: 6 pages, 7 Figures, PRD Letter accepte

Extensive search for axion dark matter over 1\,GHz with CAPP's Main Axion eXperiment

We report an extensive high-sensitivity search for axion dark matter above 1\,GHz at the Center for Axion and Precision Physics Research (CAPP). The cavity resonant search, exploiting the coupling between axions and photons, explored the frequency (mass) range of 1.025\,GHz (4.24\,$\mu$eV) to 1.185\,GHz (4.91\,$\mu$eV). We have introduced a number of innovations in this field, demonstrating the practical approach of optimizing all the relevant parameters of axion haloscopes, extending presently available technology. The CAPP 12\,T magnet with an aperture of 320\,mm made of Nb$_3$Sn and NbTi superconductors surrounding a 37-liter ultralight-weight copper cavity is expected to convert DFSZ axions into approximately $10^2$ microwave photons per second. A powerful dilution refrigerator, capable of keeping the core system below 40\,mK, combined with quantum-noise limited readout electronics, achieved a total system noise of about 200\,mK or below, which corresponds to a background of roughly $4\times 10^3$ photons per second within the axion bandwidth. The combination of all those improvements provides unprecedented search performance, imposing the most stringent exclusion limits on axion--photon coupling in this frequency range to date. These results also suggest an experimental capability suitable for highly-sensitive searches for axion dark matter above 1\,GHz.Comment: A detailed axion dark matter article with 27 pages, 22 figure

3He\mathrm{^3He} gas handling system and RF discharge for optical pumping

Axions are hypothetical pseudo scalar particles that appear in the solution of the strong CP problem. Axions can also be a dark-matter candidate if their mass is in light regime. Many of these haloscope experiments to detect axions are based on this assumption. In addition, Moody and Wilczek postulated an interaction between monopole and dipole masses that can be mediated by axions at macroscopic scale \cite{Moody}. We propose new experiment that can detect axions by measuring by pseudo-magnetic field induced between monopole and dipole. For this experiment, we have developed $^{3}$He polarization system using metastable exchange optical pumping (MEOP) technique

Quintessential Axions from a New Confining Force

Almost massless mesons created at the condensation scale of extra nonabelian gauge group can be candidates of dark energy source. This can be another motivation for introducing an additional confining force.Comment: 7 pages, 3 figure