A Neutrino Laser

[John Clark]

Nobody has built one yet but in the September 8 issue of the journal Physical Review Letters two scientists revealed the theory behind a neutrino Laser that they intend to build, and it should be small enough to fit on a table top. 

Superradiant Neutrino Lasers from Radioactive Condensates

They start with about 1 million radioactive rubidium-83 atoms, about a billionth of a billionth of a gram. Rubidium-83 produces a neutrino when it decays and normally it has a half-life of 86.2 days, but they propose a way to reduce that time by a factor of 50,000, a timeframe of just 2 1/2 minutes long. Sometime within that 2 1/2 minutes, using an effect called "superradiance", all the Rubidium-83 atoms would decay nearly instantaneously creating a huge pulse of neutrinos. And all the neutrinos would have the same energy, momentum and phase, just as photons do in a conventional laser. 

They propose using laser cooling to make a Bose-Einstein Condensate (matter in which all the atoms have the same quantum state) out of 1 million Rubidium-83 atoms. It's already ultra cold but they intend to make it even colder by injecting a small number of stable Rubidium-87 atoms, they act as a refrigerant because the stable rubidium atoms can absorb the heat given off by the radioactive atoms. The Bose-Einstein Condensate is now ultra ULTRA cold and the superradiance should occur spontaneously. Superradiance scales with the square of the number of atoms so a BEC containing even a small number of atoms made of unstable radioactive isotopes will generate an intense pulse of neutrinos.

The authors also propose that a variation of their technique could act as a super sensitive neutrino detector, sensitive enough to even detect the Cosmic Neutrino Background Radiation. That would be a very big deal because up to now the oldest thing we've ever seen is the Cosmic Microwave Background Radiation which occurred about 380,000 years after the big bang, but the Cosmic Neutrino Background Radiation happened just one second after the big bang, that was the instant when the density of matter became so low that neutrinos stopped interacting strongly with it. 

The authors even say that maybe a neutrino Laser could be used as a new form of communication. 

John K Clark    See what's on my new list at  Extropolis

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