46 research outputs found
Status of the ADMX and ADMX-HF experiments
The Axion Dark Matter eXperiment (ADMX) is in the midst of an upgrade to
reduce its system noise temperature. ADMX-HF (High Frequency) is a second
platform specifically designed for higher mass axions and will serve as an
innovation test-bed. Both will be commissioning in 2013 and taking data shortly
thereafter. The principle of the experiment, current experimental limits and
the status of the ADMX/ADMX-HF program will be described. R&D on hybrid
superconducting cavities will be discussed as one example of an innovation to
greatly enhance sensitivity.Comment: 4 pages, 3 figures, Contribution to the 8th Patras Workshop on
Axions, WIMPs and WISPs, Chicago, IL, USA, 201
Axions as Dark Matter Particles
The article of record as published may be located at http://dx.doi.org/10.1088/1367-2630/11/10/105008We review the current status of axions as dark matter. Motivation, models, constraints and experimental searches are outlined. The axion remains an excellent candidate for the dark matter and future experiments, particularly the Axion Dark Matter eXperiment (ADMX), will cover a large fraction of the axion parameter space
Pierre Sikivie and the Gift for Simple Ideas
The article of record as published may be found at http://dx.doi.org/101063/1.3489552I comment on the status and future prospects of the field of axion searches in the context of the seminal contributions of Pierre Sikivie
Resonantly Enhanced Axion-Photon Regeneration
We point out that photon regeneration-experiments that search for the axion,
or axion-like particles, may be resonantly enhanced by employing matched
Fabry-Perot optical cavities encompassing both the axion production and
conversion magnetic field regions. Compared to a simple photon regeneration
experiment, which uses the laser in a single-pass geometry, this technique can
result in a gain in rate of order , where is the finesse
of the cavities. This gain could feasibly be , corresponding to
an improvement in sensitivity in the axion-photon coupling,
, of order , permitting a practical purely
laboratory search to probe axion-photon couplings not previously excluded by
stellar evolution limits, or solar axion searches.Comment: 4 pages, 2 figure
Detailed design of a resonantly-enhanced axion-photon regeneration experiment
A resonantly-enhanced photon-regeneration experiment to search for the axion
or axion-like particles is described. This experiment is a shining light
through walls study, where photons travelling through a strong magnetic field
are (in part) converted to axions; the axions can pass through an opaque wall
and convert (in part) back to photons in a second region of strong magnetic
field. The photon regeneration is enhanced by employing matched Fabry-Perot
optical cavities, with one cavity within the axion generation magnet and the
second within the photon regeneration magnet. Compared to simple single-pass
photon regeneration, this technique would result in a gain of (F/pi)^2, where F
is the finesse of each cavity. This gain could feasibly be as high as 10^(10),
corresponding to an improvement in the sensitivity to the axion-photon
coupling, g_(agg), of order (F/pi)^(1/2) ~ 300. This improvement would enable,
for the first time, a purely laboratory experiment to probe axion-photon
couplings at a level competitive with, or superior to, limits from stellar
evolution or solar axion searches. This report gives a detailed discussion of
the scheme for actively controlling the two Fabry-Perot cavities and the laser
frequencies, and describes the heterodyne signal detection system, with limits
ultimately imposed by shot noise.Comment: 10 pages, 5 figure
On the use of dielectric elements in axion searches with microwave resonant cavities
This study explores the primary effects of dielectric materials in a resonant
cavity-based search for axion dark matter. While dielectrics prove beneficial
in numerous cases, their incorporation may lead to less-than-optimal
performance, especially for the lowest TM mode. Additionally, the stronger
confinement of the electric field inside the dielectrics can exacerbate mode
mixings, in particular for higher-order modes. Case studies have been carried
out using a combination of analytical solutions and numerical simulations. The
findings indicate dielectric cavities employing the mode
experience a significant reduction in sensitivity when compared to a similar
search conducted in a cavity at equivalent frequency using no dielectrics.Comment: 10 pages, 7 figure