We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 nu (e) candidate events with energies above 3.4 MeV compared to 365.2+/-23.7 events expected in the absence of neutrino oscillation. Accounting for 17.8+/-7.3 expected background events, the statistical significance for reactor nu (e) disappearance is 99.998%. The observed energy spectrum disagrees with the expected spectral shape in the absence of neutrino oscillation at 99.6% significance and prefers the distortion expected from nu (e) oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2). A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2) and tan((2)theta=0.40(+0.10)(-0.07), the most precise determination to date.

The detection of electron antineutrinos produced by natural radioactivity in the Earth could yield important geophysical information. The Kamioka liquid scintillator antineutrino detector (KamLAND) has the sensitivity to detect electron antineutrinos produced by the decay of 238U and 232Th within the Earth. Earth composition models suggest that the radiogenic power from these isotope decays is 16 TW, approximately half of the total measured heat dissipation rate from the Earth. Here we present results from a search for geoneutrinos with KamLAND. Assuming a Th/U mass concentration ratio of 3.9, the 90 per cent confidence interval for the total number of geoneutrinos detected is 4.5 to 54.2. This result is consistent with the central value of 19 predicted by geophysical models. Although our present data have limited statistical power, they nevertheless provide by direct means an upper limit (60 TW) for the radiogenic power of U and Th in the Earth, a quantity that is currently poorly constrained.

The Kamioka Liquid scintillator Anti-Neutrino Detector is used in a search for single neutron or twoneutron intranuclear disappearance that would produce holes in the s-shell energy level of 12 C nuclei. Such holes could be created as a result of nucleon decay into invisible modes (inv), e.g., n ! 3 or nn ! 2 . The deexcitation of the corresponding daughter nucleus results in a sequence of space and timecorrelated events observable in the liquid scintillator detector. We report on new limits for one-and twoneutron disappearance: n ! inv > 5:8 10 29 years and nn ! inv > 1:4 10 30 years at 90% C.L. These results represent an improvement of factors of 3 and >10 4 over previous experiments.

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ABSTRACT:Soluble polyimides with polyalicyclic structure were prepared by reactions of 2,3,5-tricarboxycyclopentyl acetic dianhydride (TCA-AH) with aromatic diamines. The two-step polymerization systems including poly(amic acids) synthesis and solution imidization using pyridine and acetic anhydride were performed and soluble polyimides with high inherent viscosities and high imidization ratios were obtained. TCA-AH polyimides exhibited high thermal stability in air and nitrogen, and good solubility in common polar solvents such as NMP (N-methyl-2-pyrrolidone). In comparison with soluble aromatic polyimides based on fluorine containing monomers, TCA-AH polyimides showed slightly less thermal stability and lower solubility in a few solvents.KEY WORDS Polyimide / Soluble Polyimide / Polyalicyclic Structure / 2,3,5-Tricarboxycyclopentyl Acetic Dianhydride / Solution Imidization / Thermal Stability / Solubility / Polyimides exhibit excellent thermal and mechanical properties, and have extensive engineering and microelectronics applications.