Application of the Bead Perturbation Technique to a Study of a Tunable 5 GHz Annular Cavity

Microwave cavities for a Sikivie-type axion search are subject to several constraints. In the fabrication and operation of such cavities, often used at frequencies where the resonator is highly overmoded, it is important to be able to reliably identify several properties of the cavity. Those include identifying the symmetry of the mode of interest, confirming its form factor, and determining the frequency ranges where mode crossings with intruder levels cause unacceptable admixture, thus leading to the loss of purity of the mode of interest. A simple and powerful diagnostic for mapping out the electric field of a cavity is the bead perturbation technique. While a standard tool in accelerator physics, we have, for the first time, applied this technique to cavities used in the axion search. We report initial results from an extensive study for the initial cavity used in the HAYSTAC experiment. Two effects have been investigated: the role of rod misalignment in mode localization, and mode-mixing at avoided crossings of TM/TE modes. Future work will extend these results by incorporating precision metrology and high-fidelity simulations.Comment: 6 pages, 4 figures, submitted to the 2nd Workshop on Microwave Cavities and Detectors for Axion Researc

Exploration of Wire Array Metamaterials for the Plasma Axion Haloscope

A plasma haloscope has recently been proposed as a feasible approach to extend the search for dark matter axions above 10 GHz ($\sim$ 40 $\mu$eV), whereby the microwave cavity in a conventional axion haloscope is supplanted by a wire array metamaterial. As the plasma frequency of a metamaterial is determined by its unit cell, and is thus a bulk property, a metamaterial resonator of any frequency can be made arbitrarily large, in contrast to a microwave cavity which incurs a steep penalty in volume with increasing frequency. We have investigated the basic properties of wire array metamaterials through $S_{21}$ measurements in the 10 GHz range. Excellent agreement with theoretical models is found, by which we project achievable quality factors to be of order $10^{4}$ in an actual axion search. Furthermore, schemes for tuning the array over a usable dynamic range ($30\%$ in frequency) appear practical from an engineering perspective.Comment: to be submitted to Physical Review Letters; typos correcte

SuperCDMS Cold Hardware Design

We discuss the current design of the cold hardware and cold electronics to be used in the upcoming SuperCDMS Soudan deployment. Engineering challenges associated with such concerns as thermal isolation, microphonics, radiopurity, and power dissipation are discussed, along with identifying the design changes necessary for SuperCDMS SNOLAB. The Cryogenic Dark Matter Search (CDMS) employs ultrapure 1-inch thick, 3-inch diameter germanium crystals operating below 50 mK in a dilution cryostat. These detectors give an ionization and phonon signal, which gives us rejection capabilities regarding background events versus dark matter signals.United States. Dept. of Energy (Grant DEAC02-76SF00515)United States. Dept. of Energy (Contract DC-AC02-07CH11359)National Science Foundation (U.S.) (Awards 0705052, 0902182, 1004714 and 0802575

Model of a geostationary regional transportation company (GRET) Fleet composition and facility layout. Technical report

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