大亞灣反應(yīng)堆中微子實驗及其進展-資料下載頁
2025-05-10 00:29本頁面
【正文】 ntly Proposed sites/experiments Site (proposal) Power (GW) Baseline Near/Far (m) Detector Near/Far(t) Overburden Near/Far (MWE) Sensitivity (90%CL) Starting time Braidwood (US) 270/1510 2?65/ 2?65 464/464 ~ ChoozII (France) 150/1067 10/10 60/300 ~ 2021 f 2021 n+f Daya Bay (China) 360//500/ 1800 40//40/80 260/260/910 ~ 2021 Kaska (Japan) 350/1600 6/6/2 ?6 90/90/260 ~ 2021/ 2021 Reno (S. Korea) 150/1500 20/20 230/675 ~ 2021/ 2021 大亞灣與加速器實驗的比較 Detector dimension Target mass: 20 t Dimension of target: m g Catcher thickness Isotopes Purity(ppb) 20cm(Hz) 25cm (Hz) 30cm(Hz) 40cm(Hz) 238U(1MeV) 50 232Th(1MeV) 50 40K(1MeV) 10 Total Oil buffer thickness Why three zones ? ? Three zones: – Complicated acrylic tank construction – g backgrounds on walls – Less fiducial volume ? Two zones: – Neutrino energy spectrum distorted – Neutron efficiency error due to energy scale and resolution: two zones: %, three zones % – Using 4 MeV cut can reduce the error by a factor of two, but backgrounds from b?g do not allow us to do so 2 zone 3 zone cut cut Capture on Gd Capture on H Vessel boundary Reactorrelated Uncertainties of Daya Bay Reactor Cores Syst. error due to Power Fluctuations Syst. error due to Core Positions Total syst. error 4 % % % 6 % % % Based on experience of past experiments, due to uncertainty in measuring the amount of thermal power produced, the uncorrelated error per reactor core sp ? 2%. frF and frN are fractions of the events at the far and near site from reactor r respectively. ? s s y s ? s p f Fr ? f Nr? ?2r?? The error due to power fluctuations of the reactors is given by: Energy Cuts 3 zone Cut, error ~% Cut, error~% Dominated by energy scale KamLAND ~ 1% Time Cuts Neutron time window uncertainty: ? Dt = 10 ns ? % uncertainty ? Use mon clock ? Baseline = % ? Goal = % % Loss % Loss Livetime ? Measure relative livetimes using accurate mon clock ? Use LED to simulate neutrino events ? Should be negligible error Target Volume Can be cancelled by swapping ? KamLAND: ~1% ? CHOOZ: %? ? Flowmeters – % repeatability ? Baseline = % ? Goal = % H/C and H/Gd ratio Can be cancelled by swapping ? H/C ratio – CHOOZ claims % absolute based on multiple lab analyses (bustion) – Use well defined liquid such as LAB and dodecane – Ramp。D: measure via NMR or neutron capture – Expected error: %% ? H/Gd ratio – Can be measured by neutron activated xrays and neutron capture time – For Dt = ms, ? error ~ % Cosmicmuons at the laboratory ~350 m ~97 m ~98 m ~210 m DYB LA Mid Far Elevation (m) 97 98 208 347 Flux (Hz/m2) Energy (GeV) 55 60 97 136 ? Apply modified Gaisser parametrization for cosmicray flux at surface ? Use MUSIC and mountain profile to estimate muon flux amp。 energy Fast neutron spectrum from MC Precision to determine the 9Li background in situ Spectrum of accidental background
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