Searcharxiv⌕ Search

arXiv subjects

A. Miyazaki

Publications and source records attributed to A. Miyazaki.

At least 19 recordsLinked to original sources
arXiv2026

Sensitivity of a closed dielectric haloscope to axion dark matter

We present a method to determine the sensitivity of a closed dielectric haloscope to axion dark matter. Dielectric haloscopes aim to probe the theoretically well-motivated axion mass range of ~26 $\mathrm{\mu}$eV to ~500 $\mathrm{\mu}$eV by utilizing a stack of dielectric disks and a mirror to enhance the axion-photon conversion within an external magnetic field. Their conversion volume is nearly axion-mass independent, thereby favoring large-scale designs to increase sensitivity. The large volume causes simulations to be computationally expensive and time-consuming. This paper presents a simple model that can be used to determine the sensitivity of the experiment with minimal computational resources. The model is able to describe the electromagnetic response of a closed dielectric haloscope, accounting for realistic geometric imperfections, as well as the noise introduced by the receiver system. It is applied to data taken with a MAgnetized Disk and Mirror Axion Experiment (MADMAX) prototype within the 1.6 T Morpurgo magnet at CERN. This work underpins the first axion dark matter search using a dielectric haloscope and provides the foundation for future dark matter searches with MADMAX.

astro-ph.IM↗
arXiv2024

First search for axion dark matter with a Madmax prototype

This paper presents the first search for dark matter axions with mass in the ranges 76.56 to 76.82 $\mu$eV and 79.31 to 79.53 $\mu$eV using a prototype setup for the MAgnetized Disk and Mirror Axion eXperiment (MADMAX). The experimental setup employs a dielectric haloscope consisting of three sapphire disks and a mirror to resonantly enhance the axion-induced microwave signal within the magnetic dipole field provided by the 1.6 T Morpurgo magnet at CERN. Over 14.5 days of data collection, no axion signal was detected. A 95% CL upper limit on the axion-photon coupling strength down to $|g_{a\gamma}| \sim 2 \times 10^{-11} \mathrm{GeV}^{-1}$ is set in the targeted mass ranges, surpassing previous constraints, assuming a local axion dark matter density $\rho_{a}$ of $0.3~\mathrm{GeV}/\mathrm{cm}^3$. This study marks the first axion dark matter search using a dielectric haloscope.

hep-ex↗
arXiv2024

First search for dark photon dark matter with a MADMAX prototype

We report the first result from a dark photon dark matter search in the mass range from ${78.62}$ to $83.95~\mathrm{\mu eV}/c^2$ with a dielectric haloscope prototype for MADMAX (Magnetized Disc and Mirror Axion eXperiment). Putative dark photons would convert to observable photons within a stack consisting of three sapphire disks and a mirror. The emitted power of this system is received by an antenna and successively digitized using a low-noise receiver. No dark photon signal has been observed. Assuming unpolarized dark photon dark matter with a local density of $\rho_{\chi}=0.3~\mathrm{GeV/cm^3}$ we exclude a dark photon to photon mixing parameter $\chi > 2.7 \times 10^{-12}$ over the full mass range and $\chi > 1.1 \times 10^{-13}$ at a mass of $80.57~\mathrm{\mu eV}/c^2$ with a 95\% confidence level. This is the first physics result from a MADMAX prototype and exceeds previous constraints on $\chi$ in this mass range by up to almost three orders of magnitude.

hep-ex↗
arXiv2023

Completion of Testing Series Double-spoke Cavity Cryomodules for ESS

The FREIA Laboratory at Uppsala University, Sweden, has completed the evaluation of 13 double-spoke cavity cryomodules for ESS. This is the first time double-spoke cavities will be deployed in a real machine. This paper summarizes testing procedures and statistics of the results and lessons learned.

physics.acc-ph↗
arXiv2023

Performance Analysis of Spoke Resonators, Statistics from Cavity Fabrication to Cryomodule Testing

Irène Joliot-Curie Laboratory (IJCLab) has been leading the development of spoke resonators in multiple international SRF projects, from fundamental R\&D, prototyping, to series production. The European Spallation Source (ESS) superconducting linac is the first of its kind to put into operation the spoke resonators. After three prototype cavities, 29 ESS production cavities have been processed, tested, assembled into cryomodules at IJCLab, and then shipped to Uppsala for the site acceptance test. Seven prototypes for two other major projects, Multi-purpose hYbrid Research Reactor for High-tech Application (MYRRHA) and Proton Improvement Plan II (PIP-II), designed in collaboration with external institutions, have as well been processed and tested at IJCLab. A new challenge is to fully process series cavities in industry, following the successful implementation of 1.3~GHz elliptical cavities in the other projects. This paper summarises main results obtained from fabrication to final testing, including frequency tuning strategy, performance, limitation in vertical cryostat, and identifies future direction of projects and R\&D in the field of spoke cavities.

physics.acc-ph↗
arXiv2022

Direct Determination of the Activation Energy for Diffusion of OH Radicals on Water Ice

Using a combination of photostimulated desorption and resonance-enhanced multiphoton ionization methods, the behaviors of OH radicals on the surface of interstellar ice analog was monitored at temperatures between 54 and 80 K. The OH number density on the surface of ultraviolet (UV)-irradiated compact amorphous solid water gradually decreased at temperatures above 60 K. Analyzing the temperature dependence of OH intensities with the Arrhenius equation, the decrease can be explained by recombination of two OH radicals, which is rate-limited by thermal diffusion of OH. The activation energy for surface diffusion was experimentally determined for the first time to be 0.14 +/- 0.01 eV, which is larger than or equivalent to those assumed in theoretical models. This value implies that the diffusive reaction of OH radicals starts to be activated at approximately 36 K on interstellar ice.

astro-ph.GA↗
arXiv2021

Accelerator Development at the FREIA Laboratory

The FREIA Laboratory at Uppsala University focuses on superconducting technology and accelerator development. It actively supports the development of the European Spallation Source, CERN, and MAX IV, among others. FREIA has developed test facilities for superconducting accelerator technology such as a double-cavity horizontal test cryostat, a vertical cryostat with a novel magnetic field compensation scheme, and a test stand for short cryomodules. Accelerating cavities have been tested in the horizontal cryostat, crab-cavities in the vertical cryostat, and cryomodules for ESS on the cryomodule test stand. High power radio-frequency amplifier prototypes based on vacuum tube technology were developed for driving spoke cavities. Solid-state amplifiers and power combiners are under development for future projects. We present the status of the FREIA Laboratory complemented with results of recent projects and future prospects.

physics.acc-ph↗
arXiv2020

First cold test of a crab cavity at the GERSEMI cryostat for the HL-LHC project

We tested the prototype DQW cavity in GERSEMI vertical test stand in FREIA. The performance met the specification, and our experimental procedure and infrastructure are qualified for testing crab cavities in the HL-LHC project. This was the critical milestone in the project and it also opens a new opportunity for testing superconducting cavities in FREIA.

physics.acc-ph↗
arXiv2020

Dark photon search with a gyrotron and a transition edge sensor

A dark photon, one of the candidates of light dark matter, will be searched around 0.1 meV range by using a gyrotron. The use of a Transition Edge Sensor is the key of this experiment and the expected result is promising. This search will pave a way to future axion search using similar instruments.

hep-ex↗
arXiv2020

Contamination and conditioning of the prototype double spoke cryomodule for European Spallation Source

A superconducting Double Spoke Resonator (DSR) is the technology of choice in a low energy section of a high power proton linear accelerator. At the FREIA laboratory in Uppsala University, we have tested two DSRs in a prototype cryomodule for the European Spallation Source (ESS) project. It showed that the conditioning process of these cavity packages would be the key for the series production tests. In this paper, we present the conditioning procedure that we developed, and also describe the results with a special focus on the cross-contamination observed between two high-power couplers. This study defines a standard conditioning recipe for the series DSR production for ESS and also for future similar projects in the world.

physics.acc-ph↗
arXiv2018

Two different origins of the Q-slope problem in superconducting niobium film cavities for a heavy ion accelerator at CERN

Superconducting niobium film cavities deposited on copper substrates (Nb/Cu) have suffered from strong field-dependent surface resistance, often referred to as the Q-slope problem, since their invention. We argue that the Q-slope may not be an intrinsic problem, but rather originates from a combination of factors which can be revealed in appropriate environmental conditions. In this study, extrinsic effects were carefully minimized in a series of experiments on a seamless cavity. The origin of the Q-slope in low frequency cavities is traced back to two contributions with different temperature and magnetic field dependences. The first component of Q-slope, affecting the residual resistance, is caused by trapped magnetic flux which is normally suppressed by a magnetic shield for bulk niobium cavities. The second, temperature dependent component of Q-slope, is similar to the medium-field Q-slope which is well known in bulk niobium cavities. These results are compared with theoretical models and possible future studies are proposed.

physics.acc-ph↗
arXiv2018

Determination of the BCS material parameters of the HIE-ISOLDE superconducting resonator

Superconducting material parameters of the Nb film coating on the Quarter-Wave Resonator (QWR) for the HIE-ISOLDE project were studied by fitting experimental results with the Mattis-Bardeen theory. We pointed out a strong correlation among fitted estimators of material parameters in the BCS theory, and proposed a procedure to remove the correlation by simultaneously fitting the surface resistance and effective penetration depth. Unlike previous studies, no literature values were assumed in the fitting. As surface resistance and penetration depth had a similar dependence on coherence length and mean free path, the correlation between these two parameters could not be eliminated by this fitting. The upper critical field measured by SQUID magnetometry showed complementary constraint to the RF result, and this allowed all the material parameters to be determined.

physics.acc-ph↗
arXiv2014

First Millimeter-wave Spectroscopy of the Ground-state Positronium

We report on the first measurement of the Breit-Wigner resonance of the transition from {\it ortho-}positronium to {\it para-}positronium. We have developed an optical system to accumulate a power of over 20 kW using a frequency-tunable gyrotron and a Fabry-Pérot cavity. This system opens a new era of millimeter-wave spectroscopy, and enables us to directly determine both the hyperfine interval and the decay width of {\it p-}Ps.

hep-ex↗
arXiv2012

Direct Observation of the Hyperfine Transition of the Ground State Positronium

We report the first direct measurement of the hyperfine transition of the ground state positronium. The hyperfine structure between ortho-positronium and para-positronium is about 203 GHz. We develop a new optical system to accumulate about 10 kW power using a gyrotron, a mode converter, and a Fabry-Pérot cavity. The hyperfine transition has been observed with a significance of 5.4 standard deviations. The transition probability is measured to be $A = 3.1^{+1.6}_{-1.2} \times 10^{-8}$ s$^{-1}$ for the first time, which is in good agreement with the theoretical value of $3.37 \times 10^{-8}$ s$^{-1}$.

hep-ex↗
arXiv2011

First direct measurement of positronium hyperfine splitting with sub-THz light

Positronium is an ideal system for the research of the bound state QED. The hyperfine splitting of positronium (Ps-HFS, about 203 GHz) is an important observable but all previous measurements of Ps-HFS had been measured indirectly using Zeeman splitting. There might be the unknown systematic errors on the uniformity of magnetic field. We are trying to measure Ps-HFS directly using sub-THz radiation. We developed an optical system to accumulate high power (about 10 kW) radiation in a Fabry-Pérot resonant cavity and observed the positronium hyperfine transition for the first time.

hep-ex↗
arXiv2010

Measurement of Positronium hyperfine splitting with quantum oscillation

Interference between different energy eigenstates in a quantum system results in an oscillation with a frequency which is proportional to the difference in energy between the states. Such an oscillation is observable in polarized positronium when it is placed in a magnetic field. In order to measure the hyperfine splitting of positronium, we perform the precise measurement of this oscillation using a high quality superconducting magnet and fast photon-detectors. A result of $203.324 \pm 0.039\rm{~(stat.)} \pm 0.015\rm{(~sys.)}$~GHz is obtained which is consistent with both theoretical calculations and previous precise measurements.

physics.atom-ph↗
arXiv2010

Precise measurement of Hyper Fine Structure of positronium using sub-THz light

Positronium is an ideal system for the research of the QED, especially for the QED in bound state. The discrepancy of 3.9σis found recently between the measured HFS values and the QED prediction ($O(α^3)$). It might be due to the contribution of the unknown new physics or the systematic problems in the previous all measurements. We propose new method to measure HFS precisely and directly. A gyrotron, a novel sub-THz light source is used with a high-finesse Fabry-Pérot cavity to obtain enough radiation power at 203 GHz. The present status of the optimization studies and current design of the experiment are described.

hep-ex↗