Prototyping a Laser Search for Axion-like Particles
We will prototype an experiment to probe the 1011 GeV axion-photon coupling scale suggested by recent
astroparticle data, using a novel technique of resonantly-enhanced photon regeneration. In a classical light-shining-through-walls
experiment, a laser beam is shot through a high field magnet in order to convert a small fraction of the photons into axions. The
unconverted photons are blocked by a beam dump while the axion beam passes through and into another magnet where they are regenerated
back into photons which apparently passed right through the "wall."
In order to resonantly enhance the photon-axion conversions, we will build a pair of Fabry-Perot optical cavities, one around each
magnet. These cavities will be mode-matched and phase-locked using feedback techniques pioneered by the LIGO experiment. Axions
generated in the first cavity will see a narrow resonance as they enter the second cavity, resulting in a large enhancement of the
initially small transition probability. This technique will allow us to probe extremely weak couplings, an order of magnitude beyond
previous experimental limits. The initial prototype apparatus will consist of dual phase-locked cavities, operated in a clean vacuum
chamber. The goals of the project are to develop the high-finesse optics, alignment procedures, and monitoring and data acquisition
hardware/software.
Supervisors: Young-Kee Kim, Aaron Chou(Fermilab Wilson Fellow)