Determination of the age of the earth from Kamland measurement of geo-neutrinos

Abstract

The low energy component of the antineutrino spectrum observed in the recent Kamland experiment has significant contribution from the radioactive decay of $^{238}U$ and $^{232}Th$ in the crust and mantle of the earth. By taking the ratio of the antineutrino events obeserved in two different energy ranges we can determine the present value $[Th/U]$ independent of the U,Th distribution in the earth. Comparing with the r-process initial value of $[Th/U]_0$ we determine the age of the earth as a function of $\Delta m^2$ and $Sin^2 2 \theta$. We find that the age of the earth determined from KamLAND data matches the age of solar system ($4.5 Gyrs$ from meteorites) for the LMA-I solution. For the LMA-II solution the age of the earth does not match the solar system age at 90 % C.L.