We report a new measurement of electron antineutrino disappearance using the fully constructed Daya Bay Reactor Neutrino Experiment. The final two of eight antineutrino detectors were installed in ...the summer of 2012. Including the 404 days of data collected from October 2012 to November 2013 resulted in a total exposure of 6.9×10^{5} GW_{th} ton days, a 3.6 times increase over our previous results. Improvements in energy calibration limited variations between detectors to 0.2%. Removal of six ^{241}Am-^{13}C radioactive calibration sources reduced the background by a factor of 2 for the detectors in the experimental hall furthest from the reactors. Direct prediction of the antineutrino signal in the far detectors based on the measurements in the near detectors explicitly minimized the dependence of the measurement on models of reactor antineutrino emission. The uncertainties in our estimates of sin^{2}2θ_{13} and |Δm_{ee}^{2}| were halved as a result of these improvements. An analysis of the relative antineutrino rates and energy spectra between detectors gave sin^{2}2θ_{13}=0.084±0.005 and |Δm_{ee}^{2}|=(2.42±0.11)×10^{-3} eV^{2} in the three-neutrino framework.
A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9 GW(th) reactors were ...detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3) eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(μμ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.
The detector system of the Daya Bay reactor neutrino experiment An, F.P.; Chan, W.T.; Chasman, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2016, Letnik:
811
Journal Article
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The Daya Bay experiment was the first to report simultaneous measurements of reactor antineutrinos at multiple baselines leading to the discovery of ν¯e oscillations over km-baselines. Subsequent ...data has provided the world׳s most precise measurement of sin22θ13 and the effective mass splitting Δmee2. 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.
The muon system of the Daya Bay Reactor antineutrino experiment An, F.P.; Beriguete, W.; Blyth, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2015, Letnik:
773
Journal Article
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The Daya Bay experiment consists of functionally identical antineutrino detectors immersed in pools of ultrapure water in three well-separated underground experimental halls near two nuclear reactor ...complexes. These pools serve both as shields against natural, low-energy radiation, and as water Cherenkov detectors that efficiently detect cosmic muons using arrays of photomultiplier tubes. Each pool is covered by a plane of resistive plate chambers as an additional means of detecting muons. Design, construction, operation, and performance of these muon detectors are described.
This Letter reports a measurement of the flux and energy spectrum of electron antineutrinos from six 2.9 GWth nuclear reactors with six detectors deployed in two near (effective baselines 512 and 561 ...m) and one far (1579 m) underground experimental halls in the Daya Bay experiment. Using 217 days of data, 296 721 and 41 589 inverse β decay (IBD) candidates were detected in the near and far halls, respectively. The measured IBD yield is (1.55±0.04) ×10(-18) cm(2) GW(-1) day(-1) or (5.92±0.14) ×10(-43) cm(2) fission(-1). This flux measurement is consistent with previous short-baseline reactor antineutrino experiments and is 0.946±0.022 (0.991±0.023) relative to the flux predicted with the Huber-Mueller (ILL-Vogel) fissile antineutrino model. The measured IBD positron energy spectrum deviates from both spectral predictions by more than 2σ over the full energy range with a local significance of up to ∼4σ between 4-6 MeV. A reactor antineutrino spectrum of IBD reactions is extracted from the measured positron energy spectrum for model-independent predictions.
A search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment's unique configuration of multiple baselines ...from six 2.9 GW(th) nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the 10(-3) eV(2)<|Δm(41)(2) |< 0.3 eV(2) range. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. The derived limits on sin(2) 2θ(14) cover the 10(-3) eV(2) ≲ |Δm(41)(2)| ≲ 0.1 eV(2) region, which was largely unexplored.
The aim of the study was to evaluate effects of losartan receptor I antagonist (AT) and/or angiotensin converting enzyme inhibitor (iACE) on clinical manifestations of the disease, hemodynamic ...characteristics, morphofunctional heart parameters in patients with chronic cardiac insufficiency (CHI) complicating coronary heart disease (CHD). A total of 60 patients aged 48-72 (mean 62 +/- 8.4) years with persistent symptoms of functional class II-IV CHI and left ventricular (LV) fraction = < 45% complicating CHD. They were divided into 3 groups of 20 patients each. Patients in group 1 were given losartan (50 mg daily), in group 2 lisinopril (10 mg daily), in group 3 combination of the two drugs for 24 weeks. Combined treatment produced more significant improvement of CHI symptoms than monotherapy with either drug. In all cases, the size of heart left chambers decreased while contractility of left ventricular myocardium increased but these effects were more pronounced after combined therapy.
To study effects of long-term administration of ACE inhibitor ramipril (hartil) on renin-angiotensin-aldosteron system (RAAS), dynamics of clinical symptoms of the disease and structural-functional ...indices of the right and left ventricle (RV, LI) in patients with chronic obstructive pulmonary disease (COPD) with decompensated chronic cor pulmonale (CCP).
X-ray examination, echocardiography (echo-CG), investigation of external respiration function were made in 45 patients with non-exacerbated COPD with CCP. The study group consisted of 25 COPD patients with CCP. They received ramipril (hartil) in a dose 2.5-5 mg. The control group of 20 patients did not receive ACE inhibitors.
As shown by echo-CG, administration of hartil in decompensated CCP significantly improved diastolic LV and RV functions, reduced systolic and diastolic sizes of both ventricles and atria. To treatment month 12 the changes enhanced with improvement of the systolic function. Patients with decompensated CCP who had no long-term correction of RAAS exhibited deterioration of RV systolic and diastolic function, the size of their right atrium and ventricle enlarged, blood pressure in the pulmonary artery rose.
Long-term administration of ACE inhibitor hartil in COPD patients with CCP in personally adjusted doses in outpatient conditions is effective and results in positive structural-functional changes of the right heart.
To study effects of long-term administration of fenspiride in combination with broncholytic drugs on dynamics of clinical symptoms, external respiration function and quality of life in patients with ...chronic obstructive pulmonary disease (COPD).
A comparative randomized trial of fenspiride used for 6 months in combination with broncholytic drugs enrolled 68 COPD patients. A clinical status, external respiration function were examined. Quality of life was evaluated with WHO questionnaire WHOQOL-100.
Addition of fenspiride to combined treatment of COPD attenuates COPD symptoms, normalizes blood biochemistry, improves external respiration function, raises exercise tolerance. Quality of life improved by physical and mental state scales.
Fenspiride addition to COPD treatment improves efficacy of the standard treatment and is recommended for treatment of COPD of stage I and II in combination with broncholytic drugs.
To maximize the light yield of the liquid scintillator (LS) for the Jiangmen Underground Neutrino Observatory (JUNO), a 20 t LS sample was produced in a pilot plant at Daya Bay. The optical ...properties of the new LS in various compositions were studied by replacing the gadolinium-loaded LS in one antineutrino detector. The concentrations of the fluor, PPO, and the wavelength shifter, bis-MSB, were increased in 12 steps from 0.5 g/L and <0.01 mg/L to 4 g/L and 13 mg/L, respectively. The numbers of total detected photoelectrons suggest that, with the optically purified solvent, the bis-MSB concentration does not need to be more than 4 mg/L. To bridge the one order of magnitude in the detector size difference between Daya Bay and JUNO, the Daya Bay data were used to tune the parameters of a newly developed optical model. Then, the model and tuned parameters were used in the JUNO simulation. This enabled to determine the optimal composition for the JUNO LS: purified solvent LAB with 2.5 g/L PPO, and 1 to 4 mg/L bis-MSB.
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