So what is the largest neutrino detector in the world? This discussion came up in regards to a very nice little educational video on YouTube that mentions the ANITA experiment:
(these minutephysics pieces are quite good!)
So, ANITA is the balloon-borne experiment mentioned in the video and of which I am a collaborator. But folks at IceCube claim that’s the world’s largest neutrino detector. And that’s a project I also work on. Furthermore, I was just at the South Pole working on a new neutrino detector called ARA (the Askaryan Radio Array) which has been mentioned as the largest neutrino detector in the world, even when only partially constructed. (See arxiv for a good ARA summary.)
So what’s the truth? Well, as in so many different endeavors, it comes down to the definition of largest. Or largest in what sense.
IceCube: This is an instrumented volume of a full cubic kilometer. Made up of over five thousand individual digital optical modules (DOMs) it is certainly the largest instrumented volume in the world. It uses the Cherenkov effect of neutrino-induced shower particles in the optically clear ice to image the shower and hence the neutrino.
ANITA: During an ANITA balloon flight, the payload observes a simply astonishing, more than a million square kilometers at a time. Only for certain narrow angular ranges can events form in the ice, refract through the surface and reach the balloon floating at 120,000 feet, but it is the largest observed area. This uses the Askaryan Effect which is a Cherenkov-like radio pulse emission from showers in dense materials.
ARA: The full ARA will cover hundreds of cubic kilometers of ice, but will have just 37 stations, each with four strings of four antennas. A much larger volume than IceCube, but much more sparsely instrumented due to the better attenuation length of radio than optical photons in the cold polar ice. The engineering test station that has been running since January 2011 has the largest volumetric acceptance of any neutrino detector in the world, several cubic kilometers. This also uses the radio technique.
So, largest neutrino detector in the world? Depends on your definition.
Read more about them: ANITA, IceCube on Facebook, Ice Cube on Facebook, ARA homepage, other radio neutrino efforts…RICE, ARIANNA, SalSA …
