A Talk About Axions by Professor Ed Daw

Ed started by explaining what axions are.  They are neutral particles that are extraordinarily weakly interacting and could constitute dark matter!  He talked us through the experiment being built to detect them.  He said he had “fallen” into searching for axions by his admiration of Dr. Leslie Rosenberg of the University of Washington in Seatle who leads work on the ADMX experiment.

Because 25% of cosmic matter is as yet undetected, theories such as WHIMPS  have been prevalent for many years as dark matter candidates.  Now axions have been put forward the search for them has gained momentum.

Let’s have the technical bit:  “Axion conversion into photons is stimulated by an apparatus consisting of an 8 tesla magnet and a cryogenically cooled high-Q turntable microwave cavity.  When the cavity’s resonant frequency is tuned to the axion mass, the interaction between nearby axions in the ADMX’s magnetic field is enhanced.  This results in the deposit of a very tiny amount of power (less than a yoctowatt) into the cavity”  (thanks Wikipedia).

Ed put up a photo of him standing next to the detector (wearing a hairnet) and it was taller than him!!!

He then had a brainwave.  What if you cut out the cryogenically cooled bit and a few other pieces and build a device much smaller that can detect axions in days rather than years?

So here we are.  He talked us through his theories with much enthusiasm as he did when telling us about the detection of Gravitational Waves.  He showed us a photo of his detector and of course it was striking in its simplicity.  His talk was full of humour and although I don’t profess to know fully what he was on about, I enjoyed his talk.

One last thing.  Someone asked (I shall not reveal who) where did the name “AXION” come from.  Well Professor Rosenberg liked the name of a US washing powder of the same name, and thought it might be a good name for a component of dark matter.

So there you have it.  The universe is held together by washing powder!!

Marilyn Bentley