Hawaii Anti-Neutrino Observatory

The Hawaii Anti-Neutrino Observatory (Hanohano) is a deep ocean project to detect natural neutrinos throughout the Earth and its core. Natural neutrinos (anti-electron neutrinos) arise from the decay of radioactive isotopes of Uranium, Thorium, and Potassium in the crust and mantle (geo-neutrinos). This radioactivity is believed to supply most of the earth’s internal heat, driving plate tectonics, seafloor spreading, and volcanic activity. The spectrum of neutrinos from the decay chains of Uranium and Thorium extends above the energy threshold for inverse neutron decay (1.8 MeV). Detection above background is facilitated by the delayed coincidence signal from the capture of the neutron. This double hit signature permits identification of reactor and natural radioactive decay neutrinos.


The detector concept is similar to that employed by the operating KamLAND experiment in Japan. Detection of inverse neutron decay using scintillation liquid viewed by photomultiplier tubes is traditional, starting with the seminal experiments of Reines and Cowan. The KamLAND experiment, which is situated for observing neutrinos from nuclear power reactors, demonstrates the capability for detecting lower energy geo-neutrinos. The geo-neutrino signal at the KamLAND site originates primarily from radioactive elements in the continental crust.

To reduce background from nuclear power reactors and to gain sensitivity to radioactive elements in Earth's mantle Hanohano is placed on the oceanic crust near Hawaii. There are significant engineering challenges associated with operating a sophisticated detector in a remote, deep ocean environment. Physicists and geologists at the University of Hawaii along with engineers at Makai Ocean Engineering are investigating these challenges and developing solutions.












Hanohano Related Conferences:

Geo-neutrino references

Composition of core


this site developed by steve dye, feb. 2005

updated by jgl, 5/07