HANOHANO

Hawaii Anti-Neutrino Observatory

HANOHANO is a proposed 10 kiloton liquid scintillation detector designed to be transportable and deployable in the deep ocean. For particle physics use it can be positioned ~50km offshore from a reactor complex and make measurements of the unknown neutrino oscillations mixing angle theta_13. Moreover if this angle is not too small, then it can determine the neutrino mass hierarchy, in a means not dependent upon matter effects, and relatively insensitive to systematic effects.

The other goal is to measure for the first time the neutrino flux from uranium and thorium from the Earth's mantle. This opens a new field, after the initial geoneutrino detections from KamLAND, and will help solve the mystery of the source of heat in the Earth. The heat which drives tectonics and the geomagnetic field remains controversial in source and magnitude.

Initial engineering and design studies have been carried out, along with some critical laboratory tests, and feasibility has been established. (Link to report completed under CEROS Contract No. 53439)

Neutrino Oscillation Studies

We describe a method for determining the hierarchy of the neutrino mass spectrum and theta_13 through remote detection of electron antineutrinos from a nuclear reactor. This method utilizing a single, 10-kiloton scintillating liquid detector at a distance of 50-64 kilometers from the reactor complex measures mass-squared differences involving nu_3 with a one (ten) year exposure provided sin^2(2theta_13)>0.05 (0.02). Our technique applies the Fourier transform to the event rate as a function of neutrino flight distance over neutrino energy. Sweeping over a relevant range of delta_m^2 resolves separate spectral peaks for delta_m^2_31 and delta_m^2_32. For normal (inverted) hierarchy |delta_m^2_31| is greater (lesser) than |delta_m^2_32|. This robust determination requires a detector energy resolution of 3.5%/sqrt(E). (Link to arXiv paper)

Geoneutrino Studies

The Hawaii Anti-Neutrino Observatory (Hanohano) is a deep ocean project to detect natural neutrinos throughout the Earth and its core. (Link to arXiv paper) Natural neutrinos (anti-electron neutrinos) arise from the decay of radioactive isotopes of uranium, thorium, and potassium in the crust and mantle (geo-neutrinos) and possibly from a nuclear reactor in the core (geo-reactor neutrinos). 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 (background reduction) is facilitated by the delayed coincidence signal from the capture of the neutron. Potassium neutrinos are below threshold for this reaction.

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 , the University of Maryland , the University of Alabama , and others along with engineers at Makai Ocean Engineering are investigating these challenges and developing solutions. (Link to Hanohano paper)

this site developed by steve dye, feb. 2005