Showing papers by "Sanshiro Enomoto published in 2005"
Tohoku University1, University of Tokyo2, University of Alabama3, Los Alamos National Laboratory4, Lawrence Berkeley National Laboratory5, University of California, Berkeley6, Kansas State University7, California Institute of Technology8, Drexel University9, Louisiana State University10, University of New Mexico11, Stanford University12, Imperial College London13, University of Tennessee14, Duke University15, University of North Carolina at Chapel Hill16, University of Bordeaux17
TL;DR: In this article, a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos is presented, where the observed energy spectrum disagrees with the expected spectral shape.
Abstract: We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 [overline 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 [overline 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 [overline nu ]e oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam2=7.9 -0.5 +0.6 ×10-5 eV2. A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam2=7.9 -0.5 +0.6 ×10-5 eV2 and tan2theta=0.40 -0.07 +0.10 , the most precise determination to date.
992Â citations
Tohoku University1, University of Alabama2, University of California, Berkeley3, California Institute of Technology4, Drexel University5, University of Hawaii at Manoa6, Kansas State University7, Louisiana State University8, University of New Mexico9, Stanford University10, University of Tennessee11, Duke University12, North Carolina State University13, University of North Carolina at Chapel Hill14, Centre national de la recherche scientifique15
TL;DR: Although the present data have limited statistical power, they nevertheless provide by direct means an upper limit for the radiogenic power of U and Th in the Earth, a quantity that is currently poorly constrained.
Abstract: 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 ^(238)U and ^(232)Th 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.
393Â citations
Posted Content•
TL;DR: In this paper, the Kamioka liquid scintillator anti-neutrino detector (KamLAND) is used to determine the absolute abundances of U and Th in the Earth with an accuracy sufficient for placing important constraints on Earth's accretional process and succeeding thermal history.
Abstract: The Kamioka liquid scintillator anti-neutrino detector (KamLAND) is a low-energy and low-background neutrino detector which could be a useful probe for determining the U and Th abundances of the Earth. We constructed a model of the Earth in order to evaluate the rate of geologically produced anti-neutrinos (geo-neutrinos) detectable by KamLAND. We found that KamLAND can be used to determine the absolute abundances of U and Th in the Earth with an accuracy sufficient for placing important constraints on Earth's accretional process and succeeding thermal history. The present observation of geo-neutrinos with KamLAND is consistent with our model prediction based on the bulk silicate Earth (BSE) composition within the uncertainty of the measurement. If a neutrino detector were to be built in Hawaii, where effects of the continental crust would be negligible, it could be used to estimate the U and Th content in the lower mantle and the core. Our calculation of the geo-neutrino event rate on the Earth's surface indicates that geo-neutrino observation can provide key information for testing the current models for the content and distribution of U and Th in the Earth.
7Â citations
04 Jun 2005
TL;DR: The port-forwarding package has been developed which works like a gate which opens ports at the firewall and it is enable to use the DAQ system by KONOE under the global network.
Abstract: KONOE is a toolkit for building a data acquisition, DAQ, system which is used under a network-distributed environment with an object-oriented technology. Several major functions required for a DAQ software, are collecting, recording and monitoring experiment data, and controlling a whole system. Their functions are realized more efficiently and easily by using KONOE. KONOE, so far, has been a toolkit to build a DAQ system under only a local area network, not a global network. The reason why it is not for a global network is the firewall at a connection point to the Internet because of a security reason. Therefore, standard packets to be transferred by user processes are blocked at that point. KONOE packets are also blocked by the firewall. To solve the problem, the port-forwarding package has been developed. The package works like a gate which opens ports at the firewall. The KONOE packets can pass through the firewall with using this package easily and it is enable to use the DAQ system by KONOE under the global network