Speaker
Alexander Millar
(Max Planck Institute for Phyiscs)
Description
Axions and axion-like particles are among the best-motivated
candidates for dark matter. In particular, the QCD axion is
capable of not only providing a dark matter candidate, but
is also gives a natural explanation for the strong CP
problem. Consequently, the detection of dark matter axions
is of great interest as it would solve two of the most
significant problems of modern physics. To this end, we
introduce a new method to detect galactic dark-matter axions
using dielectrics. When a dielectric interface is inside a
strong parallel magnetic field, the oscillating axion field
acts as a source of microwaves, which emerge in both
directions perpendicular to the surface. These microwaves
compensate for a discontinuity in the axion induced electric
field. Crucially, the emission rate can be boosted by
multiple parallel layers judiciously placed to achieve
constructive interference. Starting from the axion-modified
Maxwell equations, we calculate the efficiency of this new
"layered dielectric haloscope? approach. This technique may
prove useful in the well-motivated high-frequency range of
10-100 GHz (axion mass 40-400 ueV), where traditional cavity
resonators have difficulties reaching the required volume.
This would allow one to study axion dark matter generated by
the topological defects, which occur if the reheating
temperature after inflation was lower than the Peccei-Quinn
scale. Unlike a cavity resonator it is possible for
dielectric haloscopes to conduct a broadband search. In
particular, we study the relation between the power
generated and the bandwidth, the connection between the
emission and reflection functions, and the connection to
traditional cavity haloscopes.
Primary author
Alexander Millar
(Max Planck Institute for Phyiscs)
