arXiv subjects

D. B. Tanner

Publications and source records attributed to D. B. Tanner.

At least 37 records · Page 2Linked to original sources

arXiv2019

Avoided mode crossings in cylindrical microwave cavities

Axion haloscope detectors require high-$Q$ cavities with tunable TM$_{010}$ modes whose resonant electric field occupies as much of the full volume of the cavity as possible. An analytical study of the effects of longitudinal symmetry breaking within microwave cavities was conducted to better understand the mode structure. The study revealed longitudinal symmetry breaking of the cavities was the mechanism for avoided mode crossings (AMC) in cylindrical microwave cavities. The results showed the size of the gaps in the search frequency spectrum due to an AMC was roughly proportional to the magnitude of symmetry breaking for small perturbations.

physics.ins-det↗

arXiv2019

Extended Search for the Invisible Axion with the Axion Dark Matter Experiment

This paper reports on a cavity haloscope search for dark matter axions in the galactic halo in the mass range $2.81$-$3.31$ $μeV$. This search excludes the full range of axion-photon coupling values predicted in benchmark models of the invisible axion that solve the strong CP problem of quantum chromodynamics, and marks the first time a haloscope search has been able to search for axions at mode crossings using an alternate cavity configuration. Unprecedented sensitivity in this higher mass range is achieved by deploying an ultra low-noise Josephson parametric amplifier as the first stage signal amplifier.

hep-ex↗

arXiv2019

A laser heterodyne polarimeter for birefringence measurement

We introduce a laser heterodyne polarimeter designed for the precision measurement of sub $μ\mathrm{rad}$ differential phase shifts due to birefringence. The polarimeter will be used in an initial testbed for a potential future vacuum magnetic birefringence experiment at DESY. This experiment would use the 212-m-long ALPS magnet string. The vacuum magnetic birefringence signal will be amplified inside a high finesse optical cavity before it is sensed. This paper describes the polarimeter, initial results, and systematic error sources which still have to be minimized before the vacuum birefringence experiment can be realized.

physics.ins-det↗

arXiv2019

Piezoelectrically Tuned Multimode Cavity Search for Axion Dark Matter

The $μ$eV axion is a well-motivated extension to the standard model. The Axion Dark Matter eXperiment (ADMX) collaboration seeks to discover this particle by looking for the resonant conversion of dark-matter axions to microwave photons in a strong magnetic field. In this Letter, we report results from a pathfinder experiment, the ADMX "Sidecar," which is designed to pave the way for future, higher mass, searches. This testbed experiment lives inside of and operates in tandem with the main ADMX experiment. The Sidecar experiment excludes masses in three widely spaced frequency ranges (4202-4249, 5086-5799, and 7173-7203 MHz). In addition, Sidecar demonstrates the successful use of a piezoelectric actuator for cavity tuning. Finally, this publication is the first to report data measured using both the TM$_{010}$ and TM$_{020}$ modes.

hep-ex↗

arXiv2018

Coherent Detection of Ultra-weak Electromagnetic Fields

We explore the application of heterodyne interferometry for a weak-field coherent detection scheme. The methods detailed here will be used in ALPS II, an experiment designed to search for weakly-interacting, sub-eV particles. For ALPS II to reach its design sensitivity this detection system must be capable of accurately measuring fields with equivalent amplitudes on the order of 10$^{-5}$ photons per second or greater. We present initial results of an equivalent dark count rate on the order of $10^{-5}$ photons per second as well as successful generation and detection of a signal with a field strength equivalent to $10^{-2}$ photons per second.

physics.ins-det↗

arXiv2018

Infrared spectroscopy of silicon for applications in astronomy

This work focuses on the characterization of various bulk silicon (Si) samples using Fourier Transform InfraRed (FTIR) and grating spectrometers in order to get them suitable for applications in astronomy. Different samples at different impurity concentrations were characterized by measuring their transmittance in the infrared region. Various lines due to residual impurity absorption were identifed and temperature dependence of impurity absorption is presented. Concentrations of doped samples (rho ~ 0.2 - 25000 Ohm cm) were determined from impurity absorption at low temperatures and from Drude free carrier absorption at 300K.

cond-mat.mtrl-sci↗

arXiv2018

Modulation Sensitive Search for Non-Virialized Dark-Matter Axions

Non-virialized dark-matter axions may be present in the Milky Way halo in the form of low-velocity-dispersion flows. The Axion Dark Matter eXperiment performed a search for the conversion of these axions into microwave photons using a resonant cavity immersed in a strong, static magnetic field. The spread of photon energy in these measurements was measured at spectral resolutions of the order of 1 Hz and below. If the energy variation were this small, the frequency modulation of any real axion signal due to the orbital and rotational motion of the Earth would become non-negligible. Conservative estimates of the expected signal modulation were made and used as a guide for the search procedure. The photon frequencies covered by this search are 812$-$852 and 858$-$892 MHz, which correspond to an axion mass of 3.36$-$3.52 and 3.55$-$3.69 μeV. No axion signal was found, and limits were placed on the maximum local density of non-virialized axions of these masses.

astro-ph.CO↗

arXiv2018

A Search for Invisible Axion Dark Matter with the Axion Dark Matter Experiment

This Letter reports results from a haloscope search for dark matter axions with masses between 2.66 and 2.81 $μ$eV. The search excludes the range of axion-photon couplings predicted by plausible models of the invisible axion. This unprecedented sensitivity is achieved by operating a large-volume haloscope at sub-kelvin temperatures, thereby reducing thermal noise as well as the excess noise from the ultra-low-noise SQUID amplifier used for the signal power readout. Ongoing searches will provide nearly definitive tests of the invisible axion model over a wide range of axion masses.

hep-ex↗

arXiv2016

Small optic suspensions for Advanced LIGO input optics and other precision optical experiments

We report on the design and performance of small optic suspensions developed to suppress seismic motion of out-of-cavity optics in the Input Optics subsystem of the Advanced LIGO interferometric gravitational wave detector. These compact single stage suspensions provide isolation in all six degrees of freedom of the optic, local sensing and actuation in three of them, and passive damping for the other three.

physics.ins-det↗

arXiv2016

Cavity design for high-frequency axion dark matter detectors

In an effort to extend the usefulness of microwave cavity detectors to higher axion masses, above ~8 $μ$eV (~2 GHz), a numerical trade study of cavities was conducted to investigate the merit of using variable periodic post arrays and regulating vane designs for higher-frequency searches. The results show that both designs could be used to develop resonant cavities for high-mass axion searches. Multiple configurations of both methods obtained the scanning sensitivity equivalent to approximately 4 coherently coupled cavities with a single tuning rod.

physics.ins-det↗

arXiv2014

Use of X-ray scattering functions in Kramers-Kronig analysis of reflectance

Kramers-Kronig analysis is commonly used to estimate the optical properties of new materials. The analysis typically uses data from far infrared through near ultraviolet (say, 40--40,000 cm$^{-1}$ or 5 mev--5 eV) and uses extrapolations outside the measured range. Most high-frequency extrapolations use a power law, 1/$ω^n$, transitioning to $1/ω^{4}$ at a considerably higher frequency and continuing this free-carrier extension to infinity. The mid-range power law is adjusted to match the slope of the data and to give pleasing curves, but the choice of power (usually between 0.5 and 3) is arbitrary. Instead of an arbitrary power law, it is is better to use X-ray atomic scattering functions such as those presented by Henke and co-workers. These basically treat the solid as a linear combinations of its atomic constituents and, knowing the chemical formula and the density, allow the computation of dielectric function, reflectivity, and other optical functions. The "Henke reflectivity" can be used over photon energies of 10 eV--34 keV, after which a $1/ω^{4}$ continuation is perfectly fine. The bridge between experimental data and the Henke reflectivity as well as two corrections that needed to be made to the latter are discussed.

cond-mat.mtrl-sci↗

arXiv2014

Unusual Shubnikov-de Haas oscillations in BiTeCl

We report measurements of Shubnikov-de Haas (SdH) oscillations in single crystals of BiTeCl at magnetic fields up to 31 T and at temperatures as low as 0.4 K. Two oscillation frequencies were resolved at the lowest temperatures, $F_{1}=65 \pm 4$ Tesla and $F_{2}=156 \pm 5$ Tesla. We also measured the infrared optical reflectance $\left(\cal R(ω)\right)$ and Hall effect; we propose that the two frequencies correspond respectively to the inner and outer Fermi sheets of the Rashba spin-split bulk conduction band. The bulk carrier concentration was $n_{e}\approx1\times10^{19}$ cm$^{-3}$ and the effective masses $m_{1}^{*}=0.20 m_{0}$ for the inner and $m_{2}^{*}=0.27 m_{0}$ for the outer sheet. Surprisingly, despite its low effective mass, we found that the amplitude of $F_{2}$ is very rapidly suppressed with increasing temperature, being almost undetectable above $T\approx4$ K.

cond-mat.mtrl-sci↗

arXiv2014

Temperature-driven band inversion in Pb$_{0.77}$Sn$_{0.23}$Se: Optical and Hall-effect studies

Optical and Hall-effect measurements have been performed on single crystals of Pb$_{0.77}$Sn$_{0.23}$Se, a IV-VI mixed chalcogenide. The temperature dependent (10--300 K) reflectance was measured over 40--7000 cm$^{-1}$ (5--870 meV) with an extension to 15,500 cm$^{-1}$ (1.92 eV) at room temperature. The reflectance was fit to the Drude-Lorentz model using a single Drude component and several Lorentz oscillators. The optical properties at the measured temperatures were estimated via Kramers-Kronig analysis as well as by the Drude-Lorentz fit. The carriers were p-type with the carrier density determined by Hall measurements. A signature of valence intraband transition is found in the low-energy optical spectra. It is found that the valence-conduction band transition energy as well as the free carrier effective mass reach minimum values at 100 K, suggesting temperature-driven band inversion in the material. Density function theory calculation for the electronic band structure also make similar predictions.

cond-mat.str-el↗

arXiv2014

Axion Dark Matter Detection using an LC Circuit

It is shown that dark matter axions cause an oscillating electric current to flow along magnetic field lines. The oscillating current induced in a strong magnetic field $\vec{B}_0$ produces a small magnetic field $\vec{B}_a$. We propose to amplify and detect $\vec{B}_a$ using a cooled LC circuit and a very sensitive magnetometer. This appears to be a suitable approach to searching for axion dark matter in the $10^{-7}$ to $10^{-9}$ eV mass range.

hep-ph↗

arXiv2013

Dark Sectors and New, Light, Weakly-Coupled Particles

Dark sectors, consisting of new, light, weakly-coupled particles that do not interact with the known strong, weak, or electromagnetic forces, are a particularly compelling possibility for new physics. Nature may contain numerous dark sectors, each with their own beautiful structure, distinct particles, and forces. This review summarizes the physics motivation for dark sectors and the exciting opportunities for experimental exploration. It is the summary of the Intensity Frontier subgroup "New, Light, Weakly-coupled Particles" of the Community Summer Study 2013 (Snowmass). We discuss axions, which solve the strong CP problem and are an excellent dark matter candidate, and their generalization to axion-like particles. We also review dark photons and other dark-sector particles, including sub-GeV dark matter, which are theoretically natural, provide for dark matter candidates or new dark matter interactions, and could resolve outstanding puzzles in particle and astro-particle physics. In many cases, the exploration of dark sectors can proceed with existing facilities and comparatively modest experiments. A rich, diverse, and low-cost experimental program has been identified that has the potential for one or more game-changing discoveries. These physics opportunities should be vigorously pursued in the US and elsewhere.

hep-ph↗

arXiv2013

Signatures of a Pressure-Induced Topological Quantum Phase Transition in BiTeI

We report the observation of two signatures of a pressure-induced topological quantum phase transition in the polar semiconductor BiTeI using x-ray powder diffraction and infrared spectroscopy. The x-ray data confirm that BiTeI remains in its ambient-pressure structure up to 8 GPa. The lattice parameter ratio c/a shows a minimum between 2.0-2.9 GPa, indicating an enhanced c-axis bonding through pz band crossing as expected during the transition. Over the same pressure range, the infrared spectra reveal a maximum in the optical spectral weight of the charge carriers, reflecting the closing and reopening of the semiconducting band gap. Both of these features are characteristics of a topological quantum phase transition, and are consistent with a recent theoretical proposal.

cond-mat.mtrl-sci↗

arXiv2013

Quantum oscillations and optical conductivity in Rashba spin-splitting BiTeI

We report the observation of Shubnikov-de Haas (SdH) oscillations in single crystals of the Rashba spin-splitting compound BiTeI, from both longitudinal ($R_{xx}(B)$) and Hall ($R_{xy}(B)$) magnetoresistance. Under magnetic field up to 65 T, we resolved unambiguously only one frequency $F = 284.3\pm 1.3$ T, corresponding to a Fermi momentum $k_{F} = 0.093\pm 0.002$Å$^{-1}$.The amplitude of oscillations is strongly suppressed by tilting magnetic field, suggesting a highly two-dimensional Fermi surface. Combining with optical spectroscopy, we show that quantum oscillations may be consistent with a bulk conduction band having a Rashba splitting momentum $k_{R}=0.046\pm$Å$^{-1}$.

cond-mat.mtrl-sci↗

arXiv2013

Bulk Fermi surface and electronic properties of Cu$_{0.07}$Bi$_{2}$Se$_{3}$

The electronic properties of Cu$_{0.07}$Bi$_{2}$Se$_{3}$ have been investigated using Shubnikov-de Haas and optical reflectance measurements. Quantum oscillations reveal a bulk, three-dimensional Fermi surface with anisotropy $k^{c}_{F}/k^{ab}_{F}\approx$ 2 and a modest increase in free-carrier concentration and in scattering rate with respect to the undoped Bi$_{2}$Se$_{3}$, also confirmed by reflectivity data. The effective mass is almost identical to that of Bi$_{2}$Se$_{3}$. Optical conductivity reveals a strong enhancement of the bound impurity bands with Cu addition, suggesting that a significant number of Cu atoms enter the interstitial sites between Bi and Se layers or may even substitute for Bi. This conclusion is also supported by X-ray diffraction measurements, where a significant increase of microstrain was found in Cu$_{0.07}$Bi$_{2}$Se$_{3}$, compared to Bi$_{2}$Se$_{3}$.

cond-mat.mtrl-sci↗