Neutrino Astronomy - Observation Challenges

Observation Challenges

Neutrinos interact only very rarely with matter. The enormous flux of solar neutrinos racing through the Earth is sufficient to produce only 1 interaction for 1036 target atoms, and each interaction produces only a few photons or one transmuted atom. The observation of neutrino interactions requires a large detector mass, along with a sensitive amplification system.

Given the very weak signal, sources of background noise must be reduced as much as possible. The major sources of detector noise are the showers of elementary particles produced by cosmic rays striking the atmosphere, and particles produced by radioactive decay. To reduce the amount of cosmic rays, the detectors must be shielded by a large shield mass, and so are constructed deep underground, or underwater. Sources of radioactive isotopes must also be controlled as they produce energetic particles when they decay.

In order to produce any kind of image, the detector must provide information not only about the flux of neutrinos, but also their direction of travel. While several methods of detecting neutrinos exist, most do not provide directional information, and the ones that do have poor angular resolution, about 1°. To improve the angular resolution, a large array of neutrino detectors may be used.