JUNO. Determination of the Neutrino Mass Hierarchy using Reactor Neutrinos. Björn Wonsak. Universität Hamburg. Björn Wonsak 03/10/15 - PDF

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JUNO Determination of the Neutrino Mass Hierarchy using Reactor Neutrinos Universität Hamburg 1 Overview Introduction Physics Motivation and Concept Detector Design and Project Status 2 JUNO Jiangmen Underground

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JUNO Determination of the Neutrino Mass Hierarchy using Reactor Neutrinos Universität Hamburg 1 Overview Introduction Physics Motivation and Concept Detector Design and Project Status 2 JUNO Jiangmen Underground Neutrino Observatory Main goal: Mass Hierarchy (MH) Jiangmen 20kton Liquid Scintillatior Detector Collaboration formed June 2014 Start of civil engineering end 2014 Begin data taking 2020 High power nuclear power plants ( 17GW each) 3 JUNO Collaboration 4 ν-oscillation Mixing Parameters Pontecorvo-Maki-Nakagawa-Sakata (PMNS) Matrix: θ23=θatm θ13=θr, δ 0 c13 ν e 1 0 ν µ = 0 c23 s23 0 ν 0 s c s eiδ τ θ23 45 θ12=θsol 0 s13e iδ c12 s12 0 ν s12 c12 0 ν 2 0 c ν 3 θ13 9, δ? θ12 33 CP-violating phase δ CP 5 Mass Hierarchy Two mass-differences: Δm2solar = Δm221 Normal hierarchy Inverted hierarchy eV2, mass increases Δm2atm = Δm eV2 One sign unknown Two mass orderings possible νe νµ ντ 6 How to Measure Mass Hierarchy Matter effects: Long-baseline ν-exp., atmospheric ν, supernova ν Use oscillation between νe and νµ Matter potential depends on sign of m213 MSW resonance either for neutrinos or antineutrinos Vacuum oscillation: Reactor ν at medium baseline Higher order terms of oscillation depend on m213 Precision measurement of oscillation spectrum Very different approaches Complimentary Nice synergy between both 7 Mass Hierarchy with Reactor Neutrinos # of ν in Idea: Put large (20kt) LS-detector at first maximum of solar oscillation expected ν-spectrum Different oscillation frequency of subdominant terms for the two hierarchies Fourier-analysis J. Learned et. al. hep-ex/ , L. Zhan et. al Requirements for Mass Hierarchy Crucial point: Need well defined L/E Baseline L: Fixed by detector site to ~53 km Difference btw. cores 500 m Y.F. Li et al. Phys.Rev. D88 (2013) , arxiv: Energy resolution: Critical design parameter m2atm/ m2sol 33 3%/ E(MeV) required + non-stochastic term 1% 9 Requirements for Mass Hierarchy Crucial point: Need well defined L/E Baseline L: Fixed by detector site to ~53 km Difference btw. cores 500 m Y.F. Li et al. Phys.Rev. D88 (2013) , arxiv: Energy resolution: Critical design parameter m2atm/ m2sol 33 3%/ E(MeV) required + non-stochastic term 1% Addressed by: High light yield Calibrations 10 Mass Hierarchy Sensitivity Measurement with or without constraint on m2µµ Y.F. Li et al. Phys.Rev. D88 (2013) , arxiv: Sensitivity after 6 years: No constraint: χ 9 2 relative measurement self calibration of energy scale, Y.F. Li et al., Phys.Rev. D88 (2013) With 1% constraint: χ2 16 by combined analysist2k+nova [ ] 11 Precision Measurement of Mixing Parameters Fundamental to the Standard Model and beyond Probing the unitarity of UPMNS to ~1% level! Uncertainty from other oscillation parameters and systematic errors, mainly energy scale, are included m212 Current 3% JUNO 0.6% m223 5% 0.6% sin2θ12 6% 0.7% sin2θ23 10% N/A sin2θ13 14% 4% ~ 15% Will be more precise than CKM matrix elements! 12 Motivation for Precision 5σ allowed regions for solar predictions of JUNO (after 6 years) P. Ballet, S.F. King, C. Luhn, S. Pascoli and M.A. Schmidt: arxiv: Only one example! 13 Complimentarity to other Experiments JUNO: Unique precision in the solar sector m212 and θ12 enter long-baseline analysis will also affect δcp analysis ~GeV 1300km sin22θ 12 2 m 21 m232 MH sin22θ 13 sin22θ 2 3 δ CP JUNO LBNE 0.7% 0.6% 0.5% 3 4σ 14% 0.3% 5σ 3% 3% 10 14 Complimentarity to other Experiments Different systematics compared to MH from matter effects Combined analysis very effective True: Normal hierarchy JUNO Curves: Test for mass hierarchy (for about 1 yr of data) M. Blennow and T. Schwetz., JHEP 1309 (2013) Other Physics at JUNO Supernova ν Expected events (10kpc): IBD ~5000, other CC+NC+ES ~2000 Diffuse SN background Geo-neutrinos Current results: KamLAND 30±7 TNU Borexino 38.8±12 TNU JUNO expectation: ±10%(stat) ±10%(syst) Atmospheric ν Proton Decay τ yrs (90% C.L.) Possible aid to mass hierarchy? Solar ν Example: p K+ + anti-ν New physics Light sterile neutrinos Only 700m overburden Nonstandard interactions Very demanding radiopurity control Lorentz and CPT violation How to build such a detector? KamLAND Borexino Daya Bay JUNO Mass [t] ~1000 ~300 ~ Energy resolution 6%/ E 5%/ E 7.5%/ E 3%/ E Light yield [p.e./mev] 17 Central Detector Stainless steel sphere: Two options for inner vessel: Acrylic tank + stainless steel structure Ballon + acrylic structure Criterias are: 37.5 m diameter ~ PMTs (20'') ~75% coverage Engineering: Safety, lifetime, stability Physics: Radiopurity, light collection Assembly and installation Prototyp studies ongoing 18 PMTs Main requirement: 20 PMTs under discussion: High Quantenefficiency (QE) Want to reach 35% New design: MCP-PMT (Chinese industry) Photonics-type Chinese PMT New Hamamatsu PMT (SBA) Current QE: 30% (R+T) 32% (T) MCP-PMT development: Techincal issues mostly solved Successful 8'' prototypes A few 20'' prototypes 19 Liquid Scintillator Recipe: Key points: LAB + PPO + bis-msb Attenuation: λ 15m 30m Light yield Radiopurity R&D efforts: Better raw materials Improve production process Purification: (Borexino on board) Column purification (Al O λ = 25m) 2 3 Purification by charcoal Vacuum distillation 20 Detector Response MC Study Optical model: Red line: 3%/ E (analytical) QE = 35% L.Y. = 104 γ/mev, λatt = 20m Blue line: fit a/ E +b (as guidline) Software status Full optical simulation Full readout simulation (soon) Full position-reconstruction Full energy-reconstruction Full calibration (soon) Both designs: pre lim ina ry Energy resolution is plausible (enough light for 3% stochastical term, non-stochastical term under heavy investigation, but no showstopper yet) 21 My Work: Tracking Developing 3d topological tracking Only input: Vertex position and time de/dx accessible Work of B.W. 22 My Work: Topology at Low Energies (MeV) Goal: e+/e- discrimination # of events in arbitrary units Fraction of light near vertex Electrons (EKin MeV) Positrons (EKin MeV) preliminary % of light near vertex Other possible applications: Position reconstruction Energy reconstruction IBD directional reconstruction Stopping muon charge? 23 Conclusions: Physics Potential JUNO unprecedented physics instrument MH sensitivity: No constraint: Δ 2 9 With 1% constraint: Δ 2 16 Challenge: σe 3%/ E (stat.) & 1% (syst.) Strong synergy with atmospheric ν program Precision measurement of solar ν sector Probing the unitarity of UPMNS to ~1% level Complimentary to atmospheric ν program Rich additional physics program 20x larger, 2.5x more light yield Supernova ν and DSNB, geo-neutrinos, atmospheric & solar ν, proton decay, etc Summary: Project Status International collaboration formed in 2014 Civil construction started Laboratory should be ready in about 3 years. Detector optimization studies are ongoing Strong R&D program Data taking should start in Competitive schedule: In particular on the liquid scintillator and PMTs En par with PINGU One year before RENO-50 25 German Participation Groups involved + main topic U. Hamburg: Reconstruction RWTH Aachen: Electronics JGU Mainz: Physics potential U. Tübingen: WC-Veto TU München: Liquid Scintillator FZ Jülich: MPP München: Electronics (Observer) Chance for substantial contribution in key areas of the project! 26 Other JUNO related Talks Di, 17:20 T 53.3 Gruppenbericht: The Jiangmen Underground Neutrino Observatory Sebastian Lorenz Di, 17:40 T 53.4 Determination of the neutrino mass hierarchy with atmospheric neutrinos in JUNO Michael Soiron Mi, 18:20 T 72.7 Studies on muon track reconstruction with the JUNO liquid scintillator neutrino detector Christoph Genster Mi, 18:05 T 72.6 Positron discrimination in large-volume liquid scintillator detectors using 3D topological reconstruction Björn Wonsak Mi, 18:35 T 72.8 Szintillatorreinigung mit Aluminiumoxid für den JUNO - Detektor Sabrina Prummer Do, 17:30 T 93.4 Towards a Design of Readout Electronics for the JUNO Detector Marcel Weifels 27 Backup Slides 28 Global Sensitivity Prospects MH M. Blennow et al., JHEP 1403 (2014) 028 Dif fer ent risks: NOvA, LBNE: δ PINGU, INO: θ 23=40-50 JUNO: 3%-3.5% JUNO: Competitive measurement of MH using reactor neutrinos Independent of the yet-unknown CP phase and θ 23 29 JUNO Site Reactor site Yangjiang Taishan Power [GW] Civil Construction Apartments Dorm and Cafe Cable Tower Power Station Ventilation Pure water LN2 LS Area Portal Office Assembly Blding Storage 31 Jiangmen Underground Laboratory 600m vertical shaft 1300m long tunnel (40% slope) 50m diameter, 80m high cavern 32 Detector Hall 33 Schedule Civil preparation Civil construction Detector component production PMT production Detector assembly & installation Filling & data taking Electronics Full charge & time info from FADC 1GHz sampling rate channels Event rate: 50kHz In water Noise: 0.1 p.e. 35 Calibration high precision calorimetry critical validation & cross-check redundancy & 4π coverage natural calibration: fast-n captures (after μ) excellent readout behaviour upon μ H-n & C-n (all the time & everywhere) external calibration source: [0,10]MeV radioactive source calibration systems z-axis calibration with high precision spherical symmetry of response ( chimney) rope system (off-z-axis deployment) consider versatile system guide tube system (off-z-axis deployment) boundaries and near boundary regions short-lived diffusive radioactive sources full volume response map calibration UV/blue laser systems readout & scintillator monitoring/calibration in situ 36 Implosion Protection Two groups working on the implosion prevention design - Calculation and experimentation (navy lab + university lab) Shock-wave calculation & comparison to data Chain reaction experimentation and iteration planed for this year (design & experiments) 37 Supernova Neutrinos Carbon reactions as additional channels compared to WC Help to pin down flavour content Most notable: Possibility to detect νe separately JUNO Yellow Book, in preparation 38 Diffuse Supernova ν Background Most important backgrounds: - Fast neutrons and atmospheric neutrino NC reactions Efficient pulse shape discrimination is crucial! JUNO Yellow Book, in preparation 39 RENO kton LS detector Proposed site: Near Detector ~47 km from reactors Under Mt. Guemseong (450 m) Far Detector Cylindric design In line with J-PARC ν beam Everything else very similar to JUNO Schedule approximately 1 yr behind JUNO 40 Baseline Optimisation Baseline varies between different reactor cores Y.F. Li et al PRD88(2013) Shift of half an oscillation length Oscillation cancels optimisation of baseline difference = 500m 41 Non-Linearities Energy reconstruction has bias or non-linearity residuals signals might disappear or wrong (solution) Various studies show = 1% uncertainty is needed S.J. Parke et al, Nucl.Phys.Proc.Suppl. 188 (2009) X. Qian et al, PRD87(2013)3, Energy Self-Calibration Y.F. Li et al., arxiv: Based on m2ee periodic peaks Relatively insensitive to continuous backgrounds, nonperiodic structures Daya-Bay non-linearity: 1% 2% non-stochastic energy inaccuracy assumed 43 Effective Mass-Squared Differences νe and νµ disappearance experiments measure different effective atmospheric mass-squared. Differences Δ m² ee cos² (θ12 ) Δ m² 31 + sin² (θ 12) Δ m² 32 Δ m² μμ sin² (θ 12) Δ m² 31 + cos² (θ12) Δ m² 32 +sin (2 θ 12)sin(θ13 )tan(θ23 )cos(δ) Δ m² 21 With precision measurements of m2ee and m2µµ, the difference Δ m² ee Δ m² μ μ =±Δ m² 21 (cos(2 θ 12) sin(2 θ12 )sin(θ 13) tan(θ 23)cos (δ)) (+: NH, -: IH) allows to determine the MH.and possibly even cosδ at high precision H. Nunokawa et al, Phys.Rev. D72 (205) JUNO Background Assumes veto on cosmic muons! 35-40% deadtime with old reconstruction methods. 25% caused by showers or muon bundels 45 My Work: Topology at Low Energies (MeV) Goal: e+/e- discrimination Electron EKin = 2 MeV y [cm] y [cm] x [cm] x [cm] Fraction of light near vertex Position reconstruction Energy reconstruction IBD directional reconstruction Stopping muon charge? # of events Other possible applications: Electron EKin = 1 MeV Electrons (EKin 1-7 MeV) Positrons (EKin 0-6 MeV) preliminary % of light near vertx 46 Complimentarity to other Experiments Different systematics compared to MH from matter effects Combined analysis very effective 2 2 ( Δ m 31, JUNO Δ m31, Atm ) Δ χcombined Δ χ JUNO, min + Δ χ Atm, min + σ 2JUNO +σ 2Atm Synergy True: Normal hierarchy True: Inverted hierarchy term M. Blennow and T. Schwetz., JHEP 1309 (2013) Complimentarity to other Experiments Different systematics compared to MH from matter effects Combined analysis very effective True: Normal hierarchy True: Inverted hierarchy M. Blennow and T. Schwetz., JHEP 1309 (2013) Mass Hierarchy with Reactor Neutrinos # of ν in Idea: Put large (20kt) LS-Detector at first maximum of solar oscillation expected ν-spectrum Different Oscillationfrequenzy of subdominant terms for the two hierarchies Fourier-analysis Phys.Rev. D78 (2008) J. Learned et. al. hep-ex/ L. Zhan et. al Veto System Goals: Cosmogenic isotope rejection (Muon track reconstruction defines veto region) Neutron background rejection (passive shielding and possible tagging) Gammas passive shielding Water Cherenkov Pool: ~1500 PMTs 20-30kton ultrapure water with circulation system Earth magnetic field shielding Tyvek reflector film Top Tracker: OPERA Target Tracker 2cm plastic scintillator strips Crosschecks on reconstruction 50 My Work: Topology at Low Energies (MeV) Goal: e+/e- discrimination # of events Fraction of light near vertex Electrons (EKin MeV) Positrons (EKin MeV) preliminary % of light near vertex Other possible applications: Position reconstruction Energy reconstruction IBD directional reconstruction Stopping muon charge? 51
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