7 research outputs found
New measurement of θ13 via neutron capture on hydrogen at Daya Bay
No full textThis article reports an improved independent measurement of neutrino mixing angle θ13 at the Daya Bay Reactor Neutrino Experiment. Electron antineutrinos were identified by inverse β-decays with the emitted neutron captured by hydrogen, yielding a data set with principally distinct uncertainties from that with neutrons captured by gadolinium. With the final two of eight antineutrino detectors installed, this study used 621 days of data including the previously reported 217-day data set with six detectors. The dominant statistical uncertainty was reduced by 49%. Intensive studies of the cosmogenic muon-induced Li9 and fast neutron backgrounds and the neutron-capture energy selection efficiency, resulted in a reduction of the systematic uncertainty by 26%. The deficit in the detected number of antineutrinos at the far detectors relative to the expected number based on the near detectors yielded sin22θ13=0.071±0.011 in the three-neutrino-oscillation framework. The combination of this result with the gadolinium-capture result is also reported
Li4/3Ni1/3Mo1/3O2 - LiNi1/2Mn1/2O2 Binary System as High Capacity Positive Electrode Materials for Rechargeable Lithium Batteries
No full textA binary system of x Li4/3Ni1/3Mo1/3O2 - (1-x) LiNi1/2Mn1/2O2 is studied as high-capacity positive electrode materials for rechargeable lithium batteries. Structural and electrochemical properties of oxides with different compositions in this binary system are examined. Mo ordering is retained for 1 <= x <= 1/3 with a monoclinic symmetry and disappears for x <= 1/6 with a rhombohedral symmetry. Compared with Li4/3Ni1/3Mo1/3O2, partial substitution of Mn for Mo lead to the improvement of reversible capacity and reduction of polarization. For Li6/5Ni2/5Mn1/5Mo1/5O2 (x = 1/3) and Li9/8Ni7/16Mn5/16Mo1/8O2 (x = 1/6), high reversible capacities of around 200 mAh g(-1) are obtained. Improved cycling performance is achieved through the optimization of voltage ranges. Further structural characterization by ex-situ XRD reveals that the improved reversibility for the Mn-substituted samples mainly results from the suppression of Mo migration during cycling, probably associated with partial oxygen loss. (C) The Author(s) 2018. Published by ECS.Acknowledgments
The author acknowledges research funding from Advanced Low Carbon Technology Research and Development Program of the Japan Science and Technology Agency (JST) Special Priority Research Area "Next-Generation Rechargeable Battery". The synchrotron radiation experiments were performed at the BL02B2 of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal 2017B1218)
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New measurement of θ13 via neutron capture on hydrogen at Daya Bay
No full textThis article reports an improved independent measurement of neutrino mixing angle θ13 at the Daya Bay Reactor Neutrino Experiment. Electron antineutrinos were identified by inverse β-decays with the emitted neutron captured by hydrogen, yielding a data set with principally distinct uncertainties from that with neutrons captured by gadolinium. With the final two of eight antineutrino detectors installed, this study used 621 days of data including the previously reported 217-day data set with six detectors. The dominant statistical uncertainty was reduced by 49%. Intensive studies of the cosmogenic muon-induced Li9 and fast neutron backgrounds and the neutron-capture energy selection efficiency, resulted in a reduction of the systematic uncertainty by 26%. The deficit in the detected number of antineutrinos at the far detectors relative to the expected number based on the near detectors yielded sin22θ13=0.071±0.011 in the three-neutrino-oscillation framework. The combination of this result with the gadolinium-capture result is also reported
Gamma ray astronomy in the low energy range
No full textA low energy gamma ray telescope, and the results of its observations are described. The telescope consisted of four sodium iodide crystals, each of 120 cm2 area, occulted by lead discs. Charged particles are rejected using scintillation, anti-coincidence shields.The telescope was flown from Palestine, Texas in 1974. Gamma rays were observed from the Crab Nebula, the pulsar NP0 532, and the atmospheric background. No evidence for a gamma ray burst was found, giving an upper limit of less than 5.8 x 103 bursts per year of intensity greater than 1.6 x 10-6 ergs cm-2.Various types of existing, and planned, gamma ray detectors, and successful gamma ray observations are reviewed. Detailed calculations of the detection efficiency of a Double Compton telescope are presented and these results led to the development of the MISO low energy gamma ray telescope.Preliminary calculations of the detection efficiency of an Anticollimated Double Compton telescope are presented, which suggest that further, more detailed investigation of this type of detector would prove fruitful
Sub-percent precision measurement of neutrino oscillation parameters with JUNO
No full textInternational audienceJUNO is a multi-purpose neutrino observatory under construction in the south of China. This publication presents new sensitivity estimates for the measurement of the , , , and oscillation parameters using reactor antineutrinos, which is one of the primary physics goals of the experiment. The sensitivities are obtained using the best knowledge available to date on the location and overburden of the experimental site, the nuclear reactors in the surrounding area and beyond, the detector response uncertainties, and the reactor antineutrino spectral shape constraints expected from the TAO satellite detector. It is found that the , , and oscillation parameters will be determined to better than 0.5% precision in six years of data collection, which represents approximately an order of magnitude improvement over existing constraints
Observation of a rare beta decay of the charmed baryon with a Graph Neural Network
No full textThe beta decay of the lightest charmed baryon.+ c provides unique insights into the fundamental mechanism of strong and electro-weak interactions, serving as a testbed for investigating non-perturbative quantum chromodynamics and constraining the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameters. This article presents the first observation of the Cabibbosuppressed decay Lambda(+) (c) -> ne(+)v(e), utilizing 4.5 fb(-1) of electron-positron annihilation data collected with the BESIII detector. A novel Graph Neural Network based technique effectively separates signals from dominant backgrounds, notably Lambda(+) (c) -> Lambda e(+)v(e), achieving a statistical significance exceeding 10s. The absolute branching fraction ismeasured to be (3.57 +/- 0.34(stat.)+/- 0.14(syst).) x 10(-3). For the first time, the CKM matrix element |V-cd| is extracted via a charmed baryon decay as 0:208 +/- 0:011(exp): +/- 0:007(LQCD) +/- 0:001 tau(+)(Lambda) (c). This work highlights a new approach to further understand fundamental interactions in the charmed baryon sector, and showcases the power ofmodernmachine learning techniques in experimental high-energy physics.LPHE-L
