Showing papers by "Sanshiro Enomoto published in 2015"
01 Apr 2015-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The focal plane detector system for the KArlsruhe TRItium Neutrino (KATRIN) experiment as discussed by the authors consists of a multi-pixel silicon p-i-n-diode array, custom readout electronics, two superconducting solenoid magnets, an ultra high-vacuum system, a high voxel system, calibration and monitoring devices, a scintillating veto, and a custom data-acquisition system.
Abstract: The focal-plane detector system for the KArlsruhe TRItium Neutrino (KATRIN) experiment consists of a multi-pixel silicon p-i-n-diode array, custom readout electronics, two superconducting solenoid magnets, an ultra high-vacuum system, a high-vacuum system, calibration and monitoring devices, a scintillating veto, and a custom data-acquisition system. It is designed to detect the low-energy electrons selected by the KATRIN main spectrometer. We describe the system and summarize its performance after its final installation.
95 citations
TL;DR: The neutrino-electron elastic scattering rate of 862 keV Be7 solar neutrinos based on a 165.4 kt d exposure of KamLAND was measured in this article.
Abstract: We report a measurement of the neutrino-electron elastic scattering rate of 862 keV Be7 solar neutrinos based on a 165.4 kt d exposure of KamLAND. The observed rate is 582±94(kt d)−1, which corresponds to an 862-keV Be7 solar neutrino flux of (3.26±0.52)×109cm−2s−1, assuming a pure electron-flavor flux. Comparing this flux with the standard solar model prediction and further assuming three-flavor mixing, a νe survival probability of 0.66±0.15 is determined from the KamLAND data. Utilizing a global three-flavor oscillation analysis, we obtain a total Be7 solar neutrino flux of (5.82±1.02)×109cm−2s−1, which is consistent with the standard solar model predictions.
53 citations
15 Jul 2015
TL;DR: KamLAND-Zen reports on a preliminary search for neutrinoless double-beta decay with 136Xe based on 114.8 live-days after the purification of the xenon loaded liquid scintillator as mentioned in this paper.
Abstract: KamLAND-Zen reports on a preliminary search for neutrinoless double-beta decay with 136Xe based on 114.8 live-days after the purification of the xenon loaded liquid scintillator. In this data, the problematic 110mAg background peak identified in previous searches is reduced by more than a factor of 10. By combining the KamLAND-Zen pre- and post-purification data, we obtain a preliminary lower limit on the 0νββ decay half-life of T1/20ν>2.6×1025 yr at 90% C.L. The search sensitivity will be enhanced with additional low background data after the purification. Prospects for further improvements with future KamLAND-Zen upgrades are also presented.
30 citations
University of Alabama1, Institute for the Physics and Mathematics of the Universe2, Tohoku University3, California Institute of Technology4, University of Tennessee5, Colorado State University6, Louisiana State University7, University of California, Berkeley8, Lawrence Berkeley National Laboratory9, Stanford University10, University of Wisconsin-Madison11, University of North Carolina at Chapel Hill12, North Carolina State University13, Durham University14, Drexel University15, University of Hawaii at Manoa16, Kansas State University17
01 Jan 2015-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors described the methods and techniques developed to measure and efficiently extract radon decay products from liquid scintillator and reported the radio-isotope reduction factors obtained when applying various extraction methods.
Abstract: The removal of radioactivity from liquid scintillator has been studied in preparation of a low background phase of KamLAND. This paper describes the methods and techniques developed to measure and efficiently extract radon decay products from liquid scintillator. We report the radio-isotope reduction factors obtained when applying various extraction methods. During this study, distillation was identified as the most efficient method for removing radon-born lead from liquid scintillator.
16 citations
University of California, Berkeley1, Lawrence Berkeley National Laboratory2, University of Tokyo3, Tohoku University4, Osaka University5, University of California, Davis6, University of Alabama7, Lawrence Livermore National Laboratory8, University of California, Los Angeles9, California Institute of Technology10, Thomas Jefferson National Accelerator Facility11, Brookhaven National Laboratory12, Colorado State University13, Drexel University14, Arcadia University15, Carleton University16, Kansas State University17, Stanford University18, University of Tennessee19, Louisiana State University20, North Carolina Central University21, University of North Carolina at Chapel Hill22, Yale University23, University of Wisconsin-Madison24, University of Washington25, University of Amsterdam26
01 Jan 2015-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The KamLAND liquid-scintillator neutrino detector as mentioned in this paper was used to deploy radioactive sources along the vertical axis of the KamLAND detector for purposes of calibration by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable).
Abstract: We describe a compact, ultra-clean device used to deploy radioactive sources along the vertical axis of the KamLAND liquid-scintillator neutrino detector for purposes of calibration. The device worked by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable); an assortment of interchangeable radioactive sources could be attached to a weight at the end of the cable. All components exposed to the radiopure liquid scintillator were made of chemically compatible UHV-cleaned materials, primarily stainless steel, in order to avoid contaminating or degrading the scintillator. To prevent radon intrusion, the apparatus was enclosed in a hermetically sealed housing inside a glove box, and both volumes were regularly flushed with purified nitrogen gas. An infrared camera attached to the side of the housing permitted real-time visual monitoring of the cable׳s motion, and the system was controlled via a graphical user interface.
16 citations
Tohoku University1, Institute for the Physics and Mathematics of the Universe2, Osaka University3, University of Tokushima4, University of Alabama5, Lawrence Berkeley National Laboratory6, University of California, Berkeley7, University of Hawaii at Manoa8, Massachusetts Institute of Technology9, University of Tennessee10, University of North Carolina at Chapel Hill11, Durham University12, North Carolina Central University13, Duke University14, University of Washington15, University of Amsterdam16
TL;DR: In this article, the kiloton-scale liquid scintillator detector KamLAND was used to detect pre-supernova neutrinos from a star with a mass of $25~M{sun}$ at a distance less than 690~pc with 3$\sigma$ significance before the supernova.
Abstract: In the late stages of nuclear burning for massive stars ($M>8~M_{\sun}$), the production of neutrino-antineutrino pairs through various processes becomes the dominant stellar cooling mechanism. As the star evolves, the energy of these neutrinos increases and in the days preceding the supernova a significant fraction of emitted electron anti-neutrinos exceeds the energy threshold for inverse beta decay on free hydrogen. This is the golden channel for liquid scintillator detectors because the coincidence signature allows for significant reductions in background signals. We find that the kiloton-scale liquid scintillator detector KamLAND can detect these pre-supernova neutrinos from a star with a mass of $25~M_{\sun}$ at a distance less than 690~pc with 3$\sigma$ significance before the supernova. This limit is dependent on the neutrino mass ordering and background levels. KamLAND takes data continuously and can provide a supernova alert to the community.
13 citations
Tohoku University1, University of Tokyo2, Osaka University3, University of Tokushima4, University of Alabama5, University of California, Berkeley6, Lawrence Berkeley National Laboratory7, Louisiana State University8, Massachusetts Institute of Technology9, University of Tennessee10, University of Washington11, University of Amsterdam12
TL;DR: In this paper, the authors presented a search for the proton decay mode p→ν¯K+ based on an exposure of 8.97 kton-years in the KamLAND experiment.
Abstract: We present a search for the proton decay mode p→ν¯K+ based on an exposure of 8.97 kton-years in the KamLAND experiment. The liquid scintillator detector is sensitive to successive signals from p→ν¯K+ with unique kinematics, which allow us to achieve a detection efficiency of 44%, higher than previous searches in water Cherenkov detectors. We find no evidence of proton decays for this mode. The expected background, which is dominated by atmospheric neutrinos, is 0.9±0.2 events. The nonbackground-subtracted limit on the partial proton lifetime is τ/B(p→ν¯K+)>5.4×1032 years at 90% C.L.
11 citations
TL;DR: In this article, the authors search for electron anti-neutrinos from long and short-duration gamma-ray bursts (GRBs) using data taken by the KamLAND detector from August 2002 to June 2013.
Abstract: We search for electron anti-neutrinos ($\overline{
u}_e$) from long and short-duration gamma-ray bursts~(GRBs) using data taken by the KamLAND detector from August 2002 to June 2013. No statistically significant excess over the background level is found. We place the tightest upper limits on $\overline{
u}_e$ fluence from GRBs below 7 MeV and place first constraints on the relation between $\overline{
u}_e$ luminosity and effective temperature.
10 citations
Tohoku University1, Institute for the Physics and Mathematics of the Universe2, Osaka University3, University of Tokushima4, University of Alabama5, University of California, Berkeley6, Lawrence Berkeley National Laboratory7, University of Hawaii at Manoa8, Massachusetts Institute of Technology9, University of Tennessee10, University of North Carolina at Chapel Hill11, Durham University12, North Carolina Central University13, Duke University14, University of Washington15, University of Amsterdam16
TL;DR: In this article, the authors search for electron anti-neutrinos (-Ve) from long and short-duration gamma-ray bursts (GRBs) using data taken by the Kamioka Liquid Scintillator Anti-Neutrino Detector (KamLAND) from 2002 August to 2013 June.
Abstract: We search for electron anti-neutrinos (-Ve) from long- and short-duration gamma-ray bursts (GRBs) using data taken by the Kamioka Liquid Scintillator Anti-Neutrino Detector (KamLAND) from 2002 August to 2013 June. No statistically significant excess over the background level is found. We place the tightest upper limits on -Ve fluence from GRBs below 7 MeV and place first constraints on the relation between -Ve luminosity and effective temperature.
8 citations