Browsing by Author "Xu, G."

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A side-by-side comparison of Daya Bay antineutrino detectors
(1970-01-01)
An, F. P.
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An, Q.
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Bai, J. Z.
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Balantekin, A. B.
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Band, H. R.
"The Daya Bay Reactor Neutrino Experiment is designed to determine precisely the neutrino mixing angle theta(13) with a sensitivity better than 0.01 in the parameter sin(2) 2 theta(13) at the 90% confidence level. To achieve this goal, the collaboration will build eight functionally identical antineutrino detectors. The first two detectors have been constructed, installed and commissioned in Experimental Hall 1, with steady data-taking beginning September 23, 2011. A comparison of the data collected over the subsequent three months indicates that the detectors are functionally identical, and that detector-related systematic uncertainties are smaller than requirements. (C) 2012 Elsevier B.V. All rights reserved."
GPS Height Variations Affected by Ocean Tidal Loading Along the Coast of Taiwan
(2016-05-15)
Chung, Y. D.
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Yeh, Ta-Kang
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Xu, G.
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Chen, C. S.
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Hwang, C.
The Global Positioning System (GPS) uses static relative positioning to mitigate common errors and has the ability to remove the effects of ocean tidal loading (OTL). OTL effects cannot be completely removed by increasing the baseline length during GPS data processing and must be corrected with OTL models, especially in Taiwan, which is surrounded by the ocean. In this paper, we collected GPS data from ten stations that are located along the coast of Taiwan. The periodic effect of OTL is discussed through a wavelet analysis and a harmonic analysis. We also calculated the amplitudes and phases of the semi-diurnal and diurnal tides to understand the effect of OTL on the GPS heights along the coast of Taiwan. The GPS data were divided into short-term (1 month) and long-term (2 years) categories and were calculated using the Bernese 5.0 software. The tidal data and the GPS heights were transferred into a wavelet spectrum for analysis. We found that in the tidal data, the periodic M2 signal was stronger than the K1 signal, which was not the case for the GPS height data. This result indicated that the common errors were not completely removed from the GPS heights and that the corresponding period was approximately 1 day, which might result in a stronger K1 signal. Moreover, five OTL models were chosen and compared in this case. Although the GPS heights with different OTL corrections were very similar, NAO. 99b was the best fitting model for the ocean around Taiwan. Finally, we analyzed the tidal data and the M2 amplitudes and phases of the GPS heights using a harmonic analysis and compared the results with the NAO. 99b model. The comparison indicated that the best agreement occurred in southwestern Taiwan and that the poorest agreement occurred in southeastern Taiwan with a maximum error of 0.3 cm. The phase results showed that the OTL model overlapped with the tidal data in the open ocean around central Taiwan, and both the GPS heights and the heights from the OTL model were 1.5 to 2 h earlier than the tidal data.
Observation of Electron-Antineutrino Disappearance at Daya Bay
(2012-04-23)
An, F. P.
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Bai, J. Z.
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Balantekin, A. B.
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Band, H. R.
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Beavis, D.
The Daya Bay Reactor Neutrino Experiment has measured a nonzero value for the neutrino mixing angle 0(13) with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 GW(th) reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With a 43 000 ton-GW(th)-day live-time exposure in 55 days, 10 416 (80 376) electron-antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is R = 0.940 +/- 0.011(stat.) +/- 0.004(syst.). A rate-only analysis finds sin(2)2 theta(13) = 0.092 +/- 0.016(stat.) +/- 0.005(syst.) in a three-neutrino framework.
The detector system of the Daya Bay reactor neutrino experiment
(2016-03-01)
An, F. P.
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Bai, J. Z.
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Balantekin, A. B.
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Band, H. R.
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Beavis, D.
The Daya Bay experiment was the first to report simultaneous measurements of reactor antineutrinos at multiple baselines leading to the discovery of (nu) over bar (e) oscillations over km-baselines. Subsequent data has provided the world\'s most precise measurement of sin 2 2013 and the effective mass splitting Delta m(ee)(2). The experiment is located in Daya Bay, China where the cluster of six nuclear reactors is among the world\'s most prolific sources of electron antineutrinos. Multiple antineutrino detectors are deployed in three underground water pools at different distances from the reactor cores to search for deviations in the antineutrino rate and energy spectrum due to neutrino mixing. Instrumented with photomultiplier tubes, the water pools serve as shielding against natural radioactivity from the surrounding rock and provide efficient muon tagging. Arrays of resistive plate chambers over the top of each pool provide additional muon detection. The antineutrino detectors were specifically designed for measurements of the antineutrino flux with minimal systematic uncertainty. Relative detector efficiencies between the near and far detectors are known to better than 0.2%. With the unblinding of the final two detectors\' baselines and target masses, a complete description and comparison of the eight antineutrino detectors can now be presented. This paper describes the Daya Bay detector systems, consisting of eight antineutrino detectors in three instrumented water pools in three underground halls, and their operation through the first year of eight detector data-taking. (C) 2015 Elsevier B.V. All rights reserved.