Axion Search Experiments Research Articles

Josephson parametric amplifier based quantum noise limited amplifier development for axion search experiments in CAPP

Josephson parametric amplifier based quantum noise limited amplifier development for axion search experiments in CAPP

Axion magnetic resonance: A novel enhancement in axion-photon conversion

We identify a new resonance, axion magnetic resonance, that can greatly enhance the conversion rate between axions and photons. A series of axion search experiments rely on converting them into photons inside a constant magnetic field background. A common bottleneck of such experiments is the conversion amplitude being suppressed by the axion mass when ma≳10−4 eV. We point out that a spatial or temporal variation in the magnetic field can cancel the difference between the photon dispersion relation and that of the axion, hence greatly enhancing the conversion probability. We demonstrate that the enhancement can be achieved by both a helical magnetic field profile and a harmonic oscillation of the magnitude. Our approach can extend the projected ALPS II reach in the axion-photon coupling (gaγ) by two orders of magnitude at ma=10−3 eV with moderate assumptions (see .) Published by the American Physical Society 2024

Improving Amplification Bandwidth by Combining Josephson Parametric Amplifiers for Active Axion Search Experiments at IBS/CAPP

The Center for Axion and Precision Physics Research at the Institute for Basic Science in Republic of Korea is home to multiple active axion search experiments using cavity haloscopes that operate within the frequency range of 1–6 GHz. The haloscopes convert axions to photons, resulting in an output power of about 10-24\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{-24}}$$\\end{document}–10-22\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{-22}}$$\\end{document} W. To detect such a small signal amidst noise, quantum-limited noise amplifiers and ultra-low-temperature environment (a few tenths of mK) are required for all critical readout components to minimize noise from all active and passive lossy components. Our primary objective is to achieve the highest possible scanning-frequency speed, which includes the time for maintenance and system calibration. This paper presents the development and operation of low-noise amplifiers for haloscope experiments targeting different frequency ranges and provides design, operational, and performance details of the amplifiers.

Testing axionic dark matter during gravitational reheating

Assuming axions are potential dark matter (DM) candidate that make up all of the DM abundance, we discuss production of axions via (i) standard misalignment mechanism during the period of reheating and (ii) graviton-mediated 2-to-2 scattering of the inflaton and bath particles, where the inflaton ϕ oscillates in a monomial potential V(ϕ)∝ϕk with a general equation of state. Considering reheating takes place purely gravitationally, mediated by massless gravitons, we explore the viable region of the parameter space that agrees with the observed DM relic abundance, satisfying bounds from big bang nucleosynthesis and cosmic microwave background radiation. We also discuss complementarity between dedicated axion search experiments and futuristic gravitational wave search facilities in probing the viable parameter space, thanks to the presence of detectable primordial gravitational waves with an inflationary origin. Published by the American Physical Society 2024

Background rates of x-ray transition-edge sensor micro-calorimeters under a frequency domain multiplexing readout for solar axion-like particles’ detection

We report on the x-ray background rate measured with transition-edge sensors (TES) micro-calorimeters under frequency-domain multiplexing (FDM) readout as a possible technology for future experiments aiming at a direct detection of axion-like particles. Future axion helioscopes will make use of large magnets to convert axions into photons in the keV range and x-ray detectors to observe them. To achieve this, a detector array with high spectral performance and extremely low background is necessary. TES are single-photon, non-dispersive, high-resolution micro-calorimeters and represent a possible candidate for this application. We have been developing x-ray TES micro-calorimeters and an FDM readout technology in the framework of the space-borne x-ray astronomical observatories. We show that the current generation of our detectors is already a promising technology for a possible axion search experiment, having measured an x-ray background rate of 2.2(2) × 10−4 cm−2 s−1 keV−1 with a cryogenic demonstrator not optimized for this specific application. We then make a prospect to further improve the background rate down to the required value (<10−7 cm−2 s−1 keV−1) for an axion-search experiment, identifying no fundamental limits to reach such a level.

Relativistic spin dynamics conditioned by dark matter axions

The relativistic spin dynamics defined by the pseudoscalar field of dark matter axions is rigorously determined. The relativistic Hamiltonian in the Foldy–Wouthuysen representation is derived. It agrees with the previously obtained nonrelativistic Hamiltonians and the relativistic classical estimation of the axion wind effect. In the relativistic Hamiltonian, the biggest term describes the extraordinary (three orders of magnitude) enhancement of the axion wind effect in storage ring experiments as compared with experiments with immobile particles. This term defines the spin rotation about the longitudinal axis. The effects caused by the axion-induced oscillating EDM and the axion wind consist in the spin rotations about the different horizontal axes and phases of stimulating oscillations differ by pi /2. Experiments in a search for dark matter axions has been discussed. The two experimental designs for axion search experiments in storage rings have been elaborated.

Taiwan Axion Search Experiment with Haloscope: CD102 analysis details

This paper presents the analysis of the data acquired during the first physics run of the Taiwan Axion Search Experiment with Haloscope (TASEH), a search for axions using a microwave cavity at frequencies between 4.70750 and 4.79815 GHz. The data were collected from October 13, 2021 to November 15, 2021, and are referred to as the CD102 data. The analysis of the TASEH CD102 data excludes models with the axion-two-photon coupling $|{g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}|\ensuremath{\gtrsim}8.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$, a factor of 11 above the benchmark Kim-Shifman-Vainshtein-Zakharov model for the mass range $19.4687<{m}_{a}<19.8436\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$.

First Results from the Taiwan Axion Search Experiment with a Haloscope at 19.6 μeV.

This Letter reports on the first results from the Taiwan Axion Search Experiment with a Haloscope, a search for axions using a microwave cavity at frequencies between 4.707 50 and 4.798 15GHz. Apart from the nonaxion signals, no candidates with a significance of more than 3.355 were found. The experiment excludes models with the axion-two-photon coupling |g_{aγγ}|≳8.1×10^{-14} GeV^{-1}, a factor of eleven above the benchmark Kim-Shifman-Vainshtein-Zakharov model, in the mass range 19.4687<m_{a}<19.8436 μeV. It is also the first time that a haloscope experiment places constraints on g_{aγγ} in the mass region of 19.4687<m_{a}<19.7639 μeV, reaching a sensitivity 3 orders of magnitude better than the limits obtained by nonhaloscope experiments.

Taiwan axion search experiment with haloscope: Designs and operations.

We report on a holoscope axion search experiment near 19.6µeV from the Taiwan Axion Search Experiment with Haloscope collaboration. This experiment is carried out via a frequency-tunable cavity detector with a volume V = 0.234liter in a magnetic field B0 = 8T. With a signal receiver that has a system noise temperature Tsys ≅ 2.2K and an experiment time of about one month, the search excludes values of the axion-photon coupling constant gaγγ ≳ 8.1 × 10-14GeV-1, a factor of 11 above the Kim-Shifman-Vainshtein-Zakharov benchmark model, at the 95% confidence level in the mass range of 19.4687-19.8436µeV. We present the experimental setup and procedures to accomplish this search.

Pion axioproduction: The Δ resonance contribution

The process of pion axioproduction, $aN\to\pi N$, with an intermediate $\Delta$ resonance is analyzed using baryon chiral parturbation theory. The $\Delta$ resonance is included in two ways: First, deriving the $a\Delta N$-vertices, the axion is brought into contact with the resonance, and, second, taking the results of $\pi N$ elastic scattering including the $\Delta$, it is implicitly included in the form of a pion rescattering diagram. As a result, the partial wave cross section of axion-nucleon scattering shows an enhancement in the energy region around the $\Delta$ resonance. Because of the isospin breaking, the enhancement is not as pronounced as previously anticipated. However, since the isospin breaking here is much milder than that for usual hadronic processes, novel axion search experiments might still exploit this effect.

Axion Dark Matter Experiment: Detailed designand operations.

Axion dark matter experiment ultra-low noise haloscope technology has enabled the successful completion of two science runs (1A and 1B) that looked for dark matter axions in the 2.66-3.1μeV mass range with Dine-Fischler-Srednicki-Zhitnisky sensitivity [Du et al., Phys. Rev. Lett. 120, 151301 (2018) and Braine et al., Phys. Rev. Lett. 124, 101303 (2020)]. Therefore, it is the most sensitive axion search experiment to date in this mass range. We discuss the technological advances made in the last several years to achieve this sensitivity, which includes the implementation of components, such as the state-of-the-art quantum-noise-limited amplifiers and a dilution refrigerator. Furthermore, we demonstrate the use of a frequency tunable microstrip superconducting quantum interference device amplifier in run 1A, and a Josephson parametric amplifier in run 1B, along with novel analysis tools that characterize the system noise temperature.

Precision axion physics with running axion couplings

We study the renormalization group running of axion couplings while taking into account that the Standard Model can be extended to its supersymmetric extension at a certain energy scale below the axion decay constant. We then apply our results to three different classes of axion models, i.e. KSVZ-like, DFSZ-like, and string-theoretic axions, and examine if string-theoretic axions can be distinguished from others by having a different pattern of low energy couplings to the photon, nucleons and electron. We find that the low energy couplings of string-theoretic axions have a similar pattern as those of KSVZ-like axions but yet reveal a sizable difference which might be testable in future axion search experiments. We also note that the coupling of KSVZ-like QCD axions to the electron is dominated by a three-loop contribution involving the exotic heavy quark, gluons, top quark and Higgs field.

Characterization of a flux-driven Josephson parametric amplifier with near quantum-limited added noise for axion search experiments

The experimental non-observation of charge-parity (CP) symmetry violation in quantum chromodynamics is commonly referred to as the strong CP problem. The axion, a hypothetical elementary pseudoscalar, is expected to solve the strong CP problem and is also a promising candidate for dark matter. The most sensitive axion search experiments operate at millikelvin temperatures and hence rely on instrumentation that carries signals from a system at cryogenic temperatures to room temperature instrumentation. One of the biggest limiting factors affecting the parameter scanning speed of these detectors is the noise added by the components in the signal detection chain. Since the first amplifier in the chain limits the minimum noise, low-noise amplification is of paramount importance. This paper reports on the operation of a flux-driven Josephson parametric amplifier (JPA) operating at around 2.3 GHz with added noise approaching the quantum limit. The JPA was employed as a first stage amplifier in an experimental setting similar to the ones used in haloscope axion detectors. By operating the JPA at a gain of 19 dB and cascading it with two cryogenic amplifiers operating at 4 K, noise temperatures as low as 120 mK were achieved for the whole signal detection chain.

Development of a cavity with photonic crystal structure for axion searches

Abstract Two cavities of different sizes with a photonic crystal structure have been developed for axion searches. In the cavities, the dispersion relation in the photonic crystal is utilized, and so they are called “DRiPC cavities”. The size of the smaller cavity is $100 \times 100 \times 10$ mm, where 16 cylindrical metal poles with a diameter of 4 mm are introduced in a $4\times4$ grid at 20 mm intervals. In this study, the grid interval in the $x$ direction in the smaller cavity, $L_x$, was changed to investigate the resonance frequency, $Q$-value, and the electric field profile at each $L_x$. The lowest three frequencies have been compared with those simulated by the finite element method and have been found to be in excellent agreement. The lowest-frequency mode could be tuned from 5.10 GHz ($L_x = 25.0$ mm) to 6.72 GHz (13.9 mm), centered on 5.87 GHz at $L_x = 20$ mm. This wide tunability range, 27.7$\%$, was suitable for a search with a modest $Q$-value. By examining the electric field distributions with the bead-pull method, the lowest-frequency modes at $L_x=16.0$–25.0 mm were ${\rm TM_{010}}$-like. This mode was also obtained in a larger cavity ($180 \times 180 \times 20\,\text{mm} \times 2$) with the same photonic crystal structure. These results led us to conclude that a DRiPC cavity has features suitable for future axion search experiments.

Selective enhancement of the QCD axion couplings

We present a mechanism wherein the QCD axion coupling to nucleons, photons, or electrons, can be enhanced selectively without increasing the axion mass. We focus in particular on the axion-nucleon couplings, that are generally considered to be largely model-independent, and we show how nucleophilic axion models can be constructed. We discuss the implications of a nucleophilic axion for astrophysics, cosmology and laboratory searches. We present a model with enhanced axion couplings to nucleons and photons that can provide an excellent fit to the anomalous emission of hard X-rays recently observed from a group of nearby neutron stars, and we argue that such a scenario can be thoroughly tested in forthcoming axion-search experiments.

Development of highly sensitive nanoscale transition edge sensors for gigahertz astronomy and dark matter search

Terahertz (THz) and sub-terahertz (sub-THz) band detection has a key role in both fundamental interactions physics and technological applications, such as medical imaging, industrial quality control, and homeland security. In particular, transition edge sensors (TESs) and kinetic inductance detectors (KIDs) are the most employed bolometers and calorimeters in the THz and sub-THz band for astrophysics and astroparticles research. Here, we present the electronic, thermal, and spectral characterization of an aluminum/copper bilayer sensing structure that, thanks to its thermal properties and a simple miniaturized design, could be considered a perfect candidate to realize an extremely sensitive class of nanoscale TES (nano-TES) for the giga–terahertz band. Indeed, thanks to the reduced dimensionality of the active region and the efficient Andreev mirror heat confinement, our devices are predicted to reach state-of-the-art TES performance. In particular, as a bolometer the nano-TES is expected to have a noise equivalent power of 5×10−20 W/Hz and a relaxation time of ∼10 ns for the sub-THz band, typical of cosmic microwave background studies. When operated as a single-photon sensor, the devices are expected to show a remarkable frequency resolution of 100 GHz, pointing toward the necessary energy sensitivity requested in laboratory axion search experiments. Finally, different multiplexing schemes are proposed and sized for imaging applications.

QCD \u03b8-vacuum energy and axion properties

At low energies, the strong interaction is governed by the Goldstone bosons associated with the spontaneous chiral symmetry breaking, which can be systematically described by chiral perturbation theory. In this paper, we apply this theory to study the θ-vacuum energy density and hence the QCD axion potential up to next-to-leading order with N non-degenerate quark masses. By setting N = 3, we then derive the axion mass, self-coupling, topological susceptibility and the normalized fourth cumulant both analytically and numerically, taking the strong isospin breaking effects into account. In addition, the model-independent part of the axion-photon coupling, which is important for axion search experiments, is also extracted from the chiral Lagrangian supplemented with the anomalous terms up to mathcal{O}left({p}^6right) .

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 Qcavity ≪ Qaxion or Qcavity ≫ Qaxion. 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.

Exploiting higher-order resonant modes for axion haloscopes

The haloscope is one of the most sensitive approaches to the QCD axion physics within the region where the axion is considered to be a dark matter candidate. Current experimental sensitivities, which rely on the lowest fundamental TM010 mode of a cylindrical cavity, are limited to relatively low mass regions. Exploiting higher-order resonant modes would be beneficial because it will enable us to extend the search range with no volume loss and higher quality factors. This approach has been discarded mainly because of the significant degradation of form factor, and difficulty with frequency tuning. Here we introduce a new tuning mechanism concept which both enhances the form factor and yields reasonable frequency tunability. A proof of concept demonstration proved that this design is feasible for high mass axion search experiments.

First results on the search for chameleons with the KWISP detector at CAST

Abstract We report on a first measurement with a sensitive opto-mechanical force sensor designed for the direct detection of coupling of real chameleons to matter. These dark energy candidates could be produced in the Sun and stream unimpeded to Earth. The KWISP detector installed on the CAST axion search experiment at CERN looks for tiny displacements of a thin membrane caused by the mechanical effect of solar chameleons. The displacements are detected by a Michelson interferometer with a homodyne readout scheme. The sensor benefits from the focusing action of the ABRIXAS X-ray telescope installed at CAST, which increases the chameleon flux on the membrane. A mechanical chopper placed between the telescope output and the detector modulates the incoming chameleon stream. We present the results of the solar chameleon measurements taken at CAST in July 2017, setting an upper bound on the force acting on the membrane of 80 pN at 95% confidence level. The detector is sensitive for direct coupling to matter 1 0 4 ≤ β m ≤ 1 0 8 , where the coupling to photons is locally bound to β γ ≤ 1 0 11 .