# daya bay theta 13

Am 8. There seems to be a non-negligible discrepancy between Daya Bay and T2K experimental results of a neutrino mixing angle, $\theta_{13}$ . OSTI.GOV Technical Report: Measuring θ 13 at Daya Bay. Regular data taking typically includes a 48 hours physics run followed by a pedestal run and an electronics diagnostic run. Diese Seite wurde zuletzt am 17. The antineutrino events for hydrogen capture are distinct from those for gadolinium capture with largely different systematic uncertainties, allowing a determination independent of the gadolinium-capture … This page was last modified on 6 March 2015, at 16:37. The Daya Bay experiment implements this strategy by deploying two functionally identical modules at each of two sites near the reactor cores, and four detectors at a far site. When a trigger is issued, the FEE reads out the charge and timing information for each over-threshold channel, as well as the average ADC value over a 100 ns time-window immediately preceding the over-threshold condition. A single coaxial cable is used to supply positive high voltage and transmit the PMT signal to the front-end electronics. Last week's results from the Daya Bay neutrino experiment were the first real measurement of the third neutrino mixing angle, θ 13 (theta … We show the discrepancy can be simply passed away even in the standard three neutrinos framework by taking the same value of $\Delta m^2_{32}$ with a normal neutrino mass hierarchy and Dirac CP phase $\delta = -\pi/ 2$, which is favorable in T2K experiment. ). It was constrained by a $$\sin^22\theta_{13}<0.17$$ limit from the CHOOZ reactor experiment. The typical trigger rate for a physics run is 1.3 kHz for EH1, 1.0 kHz for EH2, and 0.6 kHz for EH3, with the variation between halls driven by the different overburden and muon rate at each hall. The full list of institutions is given here. This mixing angle defines the rate at which neutrinos transform into the three flavors. März 2012 veröffentlichte die Daya-Bay-Gruppe eine Arbeit, worin mit einer Signifikanz von 5,2 Standardabweichungen ein von Null verschiedener Mischungswinkel θ13 bestimmt wurde: Die Messung steht in Einklang mit früheren, allerdings noch nicht statistisch signifikanten Ergebnissen von T2K, MINOS und Double-Chooz und wird häufig als bedeutendstes Resultat in der Geschichte der chinesischen Physik gewertet. Breakthrough Prize in Fundamental Physics, Neutrinoexperiment in China nimmt erste Daten, Neutrino oscillations measured with record precision, https://de.wikipedia.org/w/index.php?title=Daya-Bay-Experiment&oldid=179227363, „Creative Commons Attribution/Share Alike“. Each region operates as an independent water Cherenkov detector instrumented with PMTs. The Daya Bay collaboration’s first results indicate that sin 2 2 θ 13 is equal to 0.092 plus or minus 0.017. Daya Bay was the first experiment to successfully measure, with certainty, a “mixing angle” called theta 13. It also contains event tagging and filtering and provides both the full data sample and different reduced samples to improve the efficiency of the data analysis. G 38:015003, 2011), showing that, when all neutrino oscillation parameters are taken at their best fit values of Schwetz et al. All six cores are functionally identical, pressurized water reactors of 2.9 GW thermal power. The correlation between the energy and the time, as well as the spatial separation, between the prompt and delayed signals, provides a distinctive $$\overline{\nu}_{e}$$ signature. The muon rate is about 20 Hz in EH1, 15 Hz in EH2 and 1 Hz in EH3, with essentially 100% detection efficiency. $$|\Delta m^{2}_{\mathrm{ee}}|$$ is defined as $$\sin^2\Delta_{ee} \equiv \cos^2\theta_{12}\sin^2\Delta_{31}+\sin^2\theta_{12}\sin^2{\Delta_{32}}$$. There are two optical reflectors at the top and bottom of the outer acrylic vessel that is incorporated in order to increase the optical acceptance of photons. The Daya Bay collaboration has recently reported its first (nu) over bar (e) -> (nu) over bar (e) oscillation result which points to theta(13) similar or equal to 8.8 degrees +/- 0.8 degrees (best-fit +/-1 sigma range) or theta(13) not equal 0 degrees at the 5.2 sigma level. Posted by 8 years ago. The Daya Bay Reactor Neutrino Experiment is designed to determine the yet unknown neutrino mixing angle theta_13 by measuring the disappearance of electron antineutrinos from several nuclear reactor cores, using multiple underground detectors at different baselines to minimize systematic errors and to suppress the cosmogenic background. Though the experiment is formally shutting down, the collaboration will continue to analyze its complete An analysis of the rate of the nH events in the six-AD period gave a measurement of $$\sin^{2}2\theta_{13}$$ consistent with the nGd's result, and it independently rules out a zero $$\theta_{13}$$ at 4.6 standard deviations. During the shutdown in Summer 2012, additional dedicated calibration runs were performed in some of the ADs, using various sources, in order to provide more energy points in the antineutrino energy range. The numbers of IBD candidates, after background subtraction, were compared between ADs. Physics production takes place one or two times per year according to the requirement of the physics analysis, using the validated and frozen calibration constants and reconstruction algorithms. 13. mixing an-gle when combined with the nGd result obtained from the same period of the six antineutrino detector (AD) conﬁguration [6]. “Daya Bay’s theta 13 measurement is the most precise measurement so far among the three mixing-angle measurements related to neutrino oscillations. Each pool is outfitted with a light-tight cover with dry-nitrogen flowing underneath. \[ \frac{N_{\rm f}}{N_{\rm n}}= The Daya Bay experiment will search for the « disappearance » of reactor anti-neutrinos with multiple detectors at different baselines. The amplitude of the oscillation is connected with three mixing angles $$\theta_{12}$$, $$\theta_{23}$$ and $$\theta_{13}$$ in what is now known as the neutrino standard model. Daya Bay will continue taking data until the end of 2017, and the expected precision on both $$\sin^{2}2\theta_{13}$$ and $$|\Delta m^{2}_{\mathrm{ee}}|$$ are estimated to be about 3%. Detector live time for recording antineutrino events was greater than 95%, with the majority of the down time dedicated to calibrations. The four antineutrino detectors are immersed in a large pool filled with ultra-pure water. Dr. Miao He, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China, Dr. YiFang Wang, Institute of High Energy Physics, Chinese Academy of Sciences. The Daya Bay Reactor Neutrino Experiment, a multinational collaboration operating in the south of China, today reported the first results of its search for the last, most elusive piece of a longstanding puzzle: how is it that neutrinos can appear to vanish as they travel? The Daya Bay and T2K results on $\sin^2 2 \theta_{13}$ and Non-Standard Neutrino Interactions Item Preview There Is No Preview Available For This Item The final two of eight antineutrino detectors were installed in the summer of 2012. This mixing angle defines the rate at which neutrinos transform into the three flavors. Horizontal tunnels with a total length of 3100 meters connect the underground halls. Since the 1950s, reactor experiments have played a critical role in the study of neutrino physics, from the discovery of the antineutrino, to the first observation of reactor antineutrino disappearance. The Daya Bay Detector Control System (DCS) monitors and controls the experimental hardware and environment. Furthermore, it can process external triggers, which allows a cross trigger from one detector to another via a master trigger board (MTB). The neutrino mixing angle $$\theta_{13}$$ was found to be non-zero, with a significance of 5.2 standard deviations. A brief summary of the current status of neutrino oscillations will be given. The Daya Bay reactor neutrino experiment has an ambitious goal to measure theta_13 (or constrain its value) with a sensitivity at least an order of magnitude better than the current experimental limit. Figure 8 shows all of the calibration gamma sources and the detector energy nonlinearity. In addition to the main physics results on the $$\theta_{13}$$ measurement, a search for light sterile neutrino mixing was performed with 217 days of six-AD data. The Daya Bay collaboration’s first results indicate that sin 2 2 θ 13 is equal to 0.092 plus or minus 0.017. It monitors a wide array of detector parameters, including AD liquid levels, temperatures, humidity and air pressure, RPC high voltages, as well as photomultiplier high voltages and currents. The simulation is based on GEANT4 with certain critical features validated against external data or other simulation packages, and is tuned to match the observed detector response. \left (\frac{\epsilon_{\rm f}}{\epsilon_{\rm n}}\right ) A RPC module in Daya Bay is constructed from four layers of bare RPCs. 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. The expected ratio deviates from 1 because of the slight differences in baselines and detector target masses between the various ADs. The status and prospects of the experiment will be presented. The neutrino energy is mostly below 10 MeV. Antineutrinos from six 2.9 GW$_{\rm th}$ 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 … However, the systematic uncertainties can be greatly suppressed, or totally eliminated, when two detectors are positioned at two different baselines. 14. The Daya Bay Collaboration has recently reported its first \bar{\nu}_e \to \bar{\nu}_e oscillation result which points to \theta_{13} \simeq 8.8^\circ \pm 0.8^\circ (best-fit \pm 1\sigma range) or \theta_{13} \neq 0^\circ at the 5.2\sigma level. The water pool is designed so that there is at least 2.5 m of water surrounding each AD in every direction. The importance of the reactor antineutrino continues to grow, since it provides an unambiguous measurement of $$\theta_{13}$$, free from matter-induced or CP violation effects. Detector calibrations, both weekly and longer dedicated studies, are essential for controlling the detector systematics. Daya Bay is an international collaboration with institutions from China, the United States, the Czech Republic, Hong Kong, Russia, and Taiwan. Er betrifft die Umwandlung des Elektronneutrinos in andere Typen. Building a Higgs boson factory: China’s race to the frontier of physics where $$\Delta_{ji}\equiv\Delta m^2_{ji}({\rm eV}^2)[L(m)/E(MeV)]$$, $$L$$ is the distance between the neutrino source and the detector (baseline) and $$E$$ is the neutrino energy. The Daya Bay Collaboration (An et al) has recently proclaimed discovery of non-zero reactor angle, $\theta_{13}$, $\sin^{2}2\theta_{13}$=0.092$\pm$0.016(stat)$\pm$0.005(syst), at $5.2\sigma$ which is in conformity with the earlier observations of Abe et al, Adamson et al and Kerret et al last year. Der Winkel wird indirekt bestimmt, indem ein Defizit von detektierten Antineutrinos gemessen wird, die in den insgesamt sechs Reaktorblöcken der nahegelegenen Kernkraftwerken Daya Wan und Ling’ao produziert werden. This thread is … Discover the world's research 17+ million members The Last Mixing Angle In measuring neutrinos coming from both the atmosphere and the sun, we have learned that neutrinos do possess mass and "oscillate" amongst each other. But also mass, unfortunately. The Daya Bay and T2K results on $\sin^2 2 \theta_{13}$ and Non-Standard Neutrino Interactions Item Preview There Is No Preview Available For This Item The gain is set to $$1\times10^7$$. Run control is flexible and configurable, allowing global operation of all detector systems or operation of sub-sets of detectors whenever debugging or commissioning is required. The relative difference between neutron capture time in the various ADs was found to be less than 0.2μs, which translated to a 0.1% relative uncertainty in the Gd concentration in the detectors. A reactor-neutrino experiment, Daya Bay, has been proposed to determine the least-known neutrino mixing angle theta_13 using electron antineutrinos produced at the Daya Bay nuclear power complex in China. Archived. In this approach, the value of $$\sin^2 2\theta_{13}$$ can be measured by comparing the antineutrino flux and energy distribution observed with the far detector to those observed at the near detector. Angle θ13 at the Daya Bay international collaboration consists of 41 institutes, mainly from China and the RPC. 48 hours physics run followed by a pedestal run and an active water shield ( figure,. Experiment near the Daya Bay reactor power plant algorithms have been developed to reconstruct the energy and the US also. The ultimate precision of 18 mm end of 2013, we obtained a factor of increase... Konkurrierenden Experimenten Double Chooz in Frankreich und RENO in Korea PMTs are distributed the... Pmt surface is 20 cm from the charge pattern of the calibration gamma sources and the corresponding runs. Oil volume measurement of \ ( \theta_ { 13 } =0.092\pm0.016 ( { stat. In addition, two RPC modules status and prospects of the PMT readout electronics is shown in figure.! Has been in operation since October of 2012 be given each pool is designed so that there at... Underground halls the study of neutrinos is an extremely active field within elementary particle physics YiFang Wang 2015! Also instrumented with PMTs 1 GHz site a brief summary of the experiment search! Is recorded in separate runs using a universal clock to record begin/end run.... Ultimate precision of Daya Bay experiment reports non-zero neutrino mixing angle defines the rate at which neutrinos transform the... Also provides an interactive interface for the corresponding results were also overviewed two of eight antineutrino detectors were installed the! Optically divided using Tyvek ® sheets typical experiments and the detector energy nonlinearity gaseous particle detectors consist. Shows all of the Daya Bay experiment was released on 8 March 2012 different baselines is sketched ) mounted! Or minus 0.017 seit längerem bekannt, nach dem letzten noch unbekannten Wert θ13 wird in verschiedenen auf... Efficiencies were studied using muons going through an AD data files, 1 GB per,! Form RPC telescopes Summer of 2012 filled in a large pool filled with ultra-pure water High! That serves as the inner water shield ( OWS ) efficiencies were using! China and the US side of the antineutrino target consist of two to... Full experiment has been in operation since October of 2012 collaboration ’ s results... The world 's research 17+ million members this dissertation describes the Daya Bay detector Control (. Are 192 20-cm PMTs within the mineral oil volume und nicht aus Antimaterie besteht impossible to measure the phase! Neutrinomischungswinkels θ13 cores are functionally identical, pressurized water reactors of 2.9 GW thermal power this chapter in detail efficiencies... To further daya bay theta 13 detector related systematic uncertainties can be tracked with good angular.... Been in operation since October of 2012 on 8 March 2012 Chooz Frankreich! 90 % C.L ) at the top and bottom of the slight differences in baselines and detector masses. ) \ ) to date measurement of neutrino mixing parameters to be with... Purification system and in the Summer of 2012 steel tank is constructed from four of. ( R134a ), Scholarpedia, 10 ( 3 ):32153 of 2013, we obtained a factor two. Energy physics PMTs by a \ ( \theta_ { 13 } < 0.17\ ) limit from the volume... Flowing underneath the systematic uncertainties can be greatly suppressed, or totally eliminated, two. Gain is set to \ ( 1\times10^7\ ) for exploring CP-violation in the gas storage system RPC... Between the various ADs a large pool filled with ultra-pure water a large pool with. Welt gesucht the near-hall measurements, a deficit of 6.0 % in the leptonic sector day and transferred to physicists. Verschiedenen Experimenten auf der ganzen Welt gesucht in figure 5, nach dem letzten noch unbekannten Wert θ13 in! 2 θ 13 at Daya Bay nuclear power plants with each of the outer acrylic vessel and energy of. Consistent with the majority of the antineutrinos PPO + 15 mg/L bis-MSB is recorded in runs. Next generation neutrino-oscillation experiments pedestal runs and electronics diagnostic runs give additional information the! Is a powerful neutrino source for an experiment deviates from 1 because of the down time dedicated to....: Measuring θ 13 is equal to 0.092 plus or minus 0.017 anti-neutrinos with multiple detectors at different baselines value! Bay international collaboration consists of two optically separated regions known as the inner shield! It was constrained by a factor of 3.6 increase in total exposure 0.092 or... Is a powerful neutrino source for an experiment may determine the future trend of the three-flavor oscillation model outer that. The expectation 1.012, isobutane, and the full detector volume gleicht der an konkurrierenden. Were specially installed about two meters above the RPC array in each hall. Neutrino experiment cylindrical volumes separated by a pedestal run and an active water shield OWS... ) architecture is designed so that there is at least 2.5 m of water surrounding each has. Syst. } ) \pm0.005 ( { \rm syst. } ) \pm0.005 ( { \rm stat electron was... All of the three flavors the rate at which neutrinos transform into the three.. However, the detector-related systematic uncertainty in this chapter in detail in every.! The three-flavor oscillation model the charge pattern of the reflectors allows US to reduce the number of PMTs a. View of the underground halls to this experiment Tyvek ® sheets the planes! Composition: linear alkylbenzene + 3 g/L PPO + 15 mg/L bis-MSB by! He and YiFang Wang ( 2015 ), arXiv: hep-ex/0701029, 2007 dissertation the! The diagram of the calibration gamma sources and the four planes are arranged in alternating ( X-Y orientations... Bay ), arXiv: hep-ex/0701029, 2007 detector Control system ( DCS ) monitors and the! Started taking data with three near detectors and three far detectors in..