The Angra Neutrino Detector

Transcription

1 The Angra Neutrino Detector Edgar Casimiro Linares João dos Anjos Centro Brasileiro de Pesquisas Físicas Workshop From Neutrinos to Dark Matter IFUG, Leon, Guanajuato, Mexico Aug, 2006

2 The Angra dos Reis Reactor Neutrino Experiment Neutrino oscillations investigations Safeguards tools development

3 Angra collaborators UNICAMP CBPF PUC RJ ANL SANDIA LLNL 17 Researchers 14 Physicists 2 Engineers 1 Post Doc 2 Students 1 PhD 1 Undergraduate Several Post docs and students applying

4 Collaborators João dos Anjos (CBPF) Ronald Shellard (PUC CBPF) Fernando Simão (CBPF) Javier Magnin (CBPF) Ademarlaudo Barbosa (CBPF) Edgar C. Linares (CBPF) Anderson Schilitz (CBPF) Hiroshi Nunokawa (PUC RJ) Ernesto Kemp (UNICAMP) Orlando L. G. Peres (UNICAMP) Marcelo Guzzo (UNICAMP) Renata Z. Funchal (USP) Nathaniel Bowden (SANDIA) Adam Bernstein ( LLNL) David Reyna (ANL) Walter Fulgione (INFN, IFSI Torino)

5 Topics Motivation for an experiment in Angra The Angra dos Reis Nuclear Plant The Detectors Construction Costs Comparison with other projects Safeguards Concluding Remarks

6 Angra dos Reis RJ Brazil MG SP RJ Angra II Angra I Angra III

7 ANGRA III preview

8 Motivations for the Angra Neutrino Detector Frontier Physics in Latin America Frontier experimental Physics taking advantage of existing nuclear reactors Angra I and Angra II. A third reactor, Angra III is expected to be added in the near future Cost relatively low Possibility to use site to host other future experiments (e.g. GRAVITON Project) Frontier Applied Physics: nuclear safeguards

9 Physics Motivations: A descoberta do fenômeno de oscilações de neutrinos implica que neutrinos têm massa e que o Modelo Padrão que descreve as interações entre partículas elementares está incompleto. Estas observações podem ter consequências profundas para a astrofísica: violação de CP no setor leptônico pode ser a chave para entendermos a assimetria matéria antimatéria no universo. A extensão mínima do Modelo Padrão requer 3 auto estados de massa, ν 1, ν 2, ν 3 e uma matriz unitária U que relacione a base de estados de massa à base de estados de sabor.

10 Extensão do Modelo Padrão: A extensão mínima do Modelo Padrão requer sete parametros: 3 massas de neutrinos m 1, m 2 e m 3 3 ângulos de mistura θ 12, θ 23, e θ 13 1 fase δ associada à violação de CP. As probabilidades de oscilação dependem das diferenças de massas ao quadrado m 2 12 = m 2 2 m 1 2 e m 2 23 = m 3 2 m 2 2

11 Extensão do Modelo Padrão: O desafio experimental no estudo de oscilações de neutrinos é medir com a maior precisão possível os parâmetros θ 12, θ 23, θ 13, m 2 12, m 2 23, e δ. Dados das experiências SNO, KamLAND e Super Kamiokande determinaram θ 12 com precisão de 10% e m 2 12 de 10 20%. Dados de neutrinos atmosféricos de Super Kamiokande e do experimento c/ acelerador K2K determinaram θ 23 e m 2 23 (~10% ) Só existe limite superior para θ 13 pelo experimento de reator nuclear CHOOZ. Medida de θ 13 é fundamental: fase δ de violação de CP só pode ser medida se θ 13 0

12 Neutrino Mixing Matrix Experimental status c osθ sin θ 0 sinθ cos i δ cosθ13 0 e sin θ 13 cosθ12 sinθ si nθ 12 cosθ i δ 23 θ 23 e sinθ 13 0 cos θ 13 Atmospheric Reactores and LBL Solar The parameters θ 23 e m 2 23 can be determined using atmospheric neutrino data observed with the detector SuperKamiokande and in the accelerator experiment K2K (precision ~10% ) Data from experiments SNO, KamLAND and SuperKamiokande can be used to determine θ 12 e m 2 12 within 10 20% precision. So far there exists only an upper limit for θ 13 obtained by an experiment performed with the nuclear reactor CHOOZ. sin 2 (2 θ 13 ) < 0.2

13 Atmospheric + Accelerator: Θ 23 = (45 ± 7) Solar + KamLand: Θ 12 = (33 ± 3) Neutrino Mixing Matrix = ν ν ν ν ν ν δ δ τ µ c s s c c e s e s c c s s c i i e θ sol θ 13, δ θ atm Reactor (CHOOZ): Θ 13 < 13 (sin 2 (2Θ 13 ) < 0.2)

14 Motivations for the Angra experiment Scientific Interest : Measurement of θ 13 is important for the investigation of CP violation in the leptonic sector: CP violation phase δ can be measured only if θ 13 0 Physics Advantages of Angra Pure measurement of θ 13, with no matter effects or parameter degeneracy Low cosmic background: shielding of m.w.e. High luminosity: (4 GW reactor, 50 and 500 tons detectors) Precise measurement of the energy spectrum

15 θ 13 & reactor experiments The oscillation signal <E ν > ~ a few MeV only disappearance experiments sin 2 (2θ 13 ) measurement independent of δ-cp 1-P(ν e ν e ) = sin 2 (2θ 13 )sin 2 ( m 2 31 L/4E) + O( m 2 21 / m 2 31 ) weak dependence in m 2 21 Few-MeV ν e + short baselines negligible matter effects (O[10-4 ] ) sin 2 (2θ 13 ) measurement independent of sign( m 2 13 km

16 Motivations for the Angra experiment Support from the Nuclear community ELETRONUCLEAR (Company Operating the reactor) CNEN (Comissão Nacional de Energia Nuclear)

17 Neutrino Reactor Experiments Nuclear Reactors give offν e resulting from the β decay of neutrons coming from fission fragments Copious source: about νe s 1 per nuclear core Nuclear Reactor E < 10 MeV Onlyν e produced at reactors Only disappearance experiments possible

18 How to look for oscillations and measure θ? 13 Oscillation effects are to be observed by comparing the neutrino flux measurements in two detectors installed at different distances from the reactor core The observation of disappearance of electron antineutrinos is the signature of the oscillation and it provides a measure of θ 13

19 The Concept P(ν e ν e ) = 1-sin 2 (2θ 13 )sin 2 ( m 2 31 L/4E) Mesurement of θ 13 Near detector Far detector Nuclear Reactor Cores Near Detector Far Detector ν e ν e,µ,τ Source of electron antineutrinos ν e /s e.g. 280 m e.g m

20 The oscillation signal Far Spectrum Near Spectrum sin 2 (2θ 13 )=0,12 m 2 atm = ev km Far/Near ratio

21 Antineutrino Flux Data: Thermal Power: 4 GW Mean Energy per fision: ~ MeV Fision Rate: N f =1.22x10 20 fisions/s Number of free protons in a 1 ton scintillator detector: n p = 9.3x Mean cross section <σ> E : 5.825x10 43 cm 2 /fision Event rate at a distance L of the core of the reactor N= N f <σ> E n p /(4 π L 2 )

22 Antineutrino Flux Antineutrino Flux: Φ ν = 1 21 P th [ GW ] s cm 2 4 π D W [ MeV ] D = distance from reactor core [50 m] P th = delivered thermal power [4 GW] W = energy release per fission [ MeV] Φ ν = s 1 cm 2

23 Angra dos Reis RJ Brazil MG SP RJ Angra II Angra I Angra III

24 The Angra dos Reis Nuclear Reactors 3 reactors: 2 in operation + 1 planned Reactor (start of operation) Thermal Power (GW) Duty Cycle Fuel Cycle Angra I (1985) % ~1,5 years Angra II (2000) 4.0 ~ 1.2 x f/s 90 % ~1,3 years Angra III Planned >

25 View of the Experimental Layout Morro do Frade Zoom Out Far Site L = 1500 m Tunnel Entrance Angra I Near Site (100m underground)

26 Configuration Morro do Frade reactors Near Detector (reference): 50 ton (7.2 m diameter) 300 m from reactor 250 mwe. Far Detector (oscillation): 500 ton (12.5 m diameter) m from reactor mwe. (under morro do Frade ) Very Near Detector: 1 ton (prototype) < 70 m from reactor Detector Design: 3 volumes

27 Far Site Sites Near Site Reactor Very Near Detector

28 Protoype (Very Near) Detector D = m from core Shielding: 20 < d < 50 mwe reactor detector High rate: ~ 10 3 events /day Little shielding for µ ~ 5 10% dead time with active veto

29 Configuration Morro do Frade reactors Near Detector (reference): 50 ton (7.2 m diameter) 300 m from reactor 250 mwe. Far Detector (oscillation): 500 ton (12.5 m diameter) m from reactor mwe. (under morro do Frade ) Very Near Detector: 1 ton (prototype) < 70 m from reactor Detectores Design: 3 volumes

30 Antineutrino Detection Antineutrino interactions are observed through the inverse beta decay process: + ν e + p e + n Antineutrinos coming from the reactor interact with protons from target (Liquid Scintillator + Gadolinium) The signature of the neutrino interaction is the detection of a prompt positron signal and a (different) neutron delayed (~150 µs) signal

31 The Detection Principle ν e γ e + γ n Muon veto (plastic scintillator paddles) Central Volume (target) scintillator + Gd (~0.5 g/l) External Volume Gamma catcher (liquid scintillator) PMT s

32 ν + p e + + e n Prompt event E prompt E ν E n 0.8 MeV Q~1.8 MeV Threshold n + Gd Delayed event Gd * + γ ' s (~ 8 MeV) MeV 6-11 MeV Prompt e+, E P =1-8 MeV, visible energy Delayed neutron capture on Gd, E D =8 MeV Time correlation: τ 30µsec Space correlation: < 1m 3 Prompt Delayed signals some pulse shape discrimination possible Directionality: weak & statistical (to be studied for the future: R&D)

33 Very Near (prototype) Detector: 3 volume Design A) Target Liquid Scintillator + Gd B) Gamma Catcher Liquid Scintillator C) Buffer Mineral Oil (8 ) D) Vert Scint Paddles (veto) E) X Y Hor Scint Paddles (veto)

34 Protoype Detector Status: Proposal submitted to the CNEN (within the framework of cooperation program with IAEA) Installation and localization under discussion with ELETRONUCLEAR (safety considerations) Design and Project: Argonne + CBPF + INFN + LLNL + Saclay + UNICAMP Estimated cost: ~ KUSD 500

35 Muon Background Intensity vs Depth 10 0 µ vertical intensity (cm 2 s 1 str 1 ) x10 4 1x Bugey Palo Verde D Chooz / Braidwood Kaska Daya Bay Angra Kamioka Gran Sasso Far Detector Depth (m.w.e.)

36 Expected Event Rates Detectors Very Near Near Far Signal (Events/Day) (50m) (300m) (1500m) Muon Rate 150 ~ (Hz)

37 Background Correlated from cosmic muon induced neutrons. More insidious when neutrons are produced by cosmic muon spallation and capture on materials outside the veto counter protection Uncorrelated hits from cosmic rays and natural radioactivity

38 ANGRA II: Probability ofν survival E min = 1.8 MeV; 95%@5MeV (Far Detector) e ) ν e P ( ν 1,0 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 Near Detector: 0.3 km Far Detector: 1.5 km E = 1.8 MeV E = 5.0 MeV E = 1.8 MeV 0,0 0, L/E [km/mev]

39 Costs: civil engineering

40 Costs: detectors Near 1 ton Detector detector (~1m 3 ) Near Far Detector Far Acrílico (2 esferas concentricas) (scaling from SNO) Aço / Suporte Estrutural (esfera exterior + suportes PMT) Eletronica ($100/canal + $1K/PMT) Óleo Mineral ($553 / ton) $3M $200K $1.2M (1054 Canais) $70K $11.5M $600K $3.6M (3293 Canais) $232K Cintilador Liquido (sem Gadolinium) ($1190 / ton) SubTotal $100K $4.6M $730K $16.7M Total / Detector (design, contingência, etc..ie. X 2) $9.2M $33.4M

41 h3 Comparison with other ν Reactor Experiments

42 Diapositiva 41 h3 hepvb, 19/09/2005

43 2006: 2004: Detector sites Penly Chooz Double Cruas Chooz Braidwood Krasnoyarsk Daya bay Reno Diablo Canyon Kashiwasaki Kaska Taiwan Angra 1 st generation: sin 2 (2θ 13 )~ Un complexe de réacteurs 2 m & ~1-2 km 2 nd generation: sin 2 (2θ 13 )~

44 2006: Non Proliferation detectors Double Chooz San Onofre Angra 2006

45 h2 Comparison with other ν Reactor experiments Power <Power> Location Detectors GW th GW th km/ton/mwe Angra Brazil 0.3/50/ /500/2000 Braidwood Illinois US 0.27/130/ /130/450 Daya Bay 11.6 (17.4 after 2010) 9.9 (14.8 after 2010) China 0.36/40/ /40/260 ~1.75/80/910 Double Chooz France 0.15/10.2/ /10.2/300 KASKA Japan 0.35/6/90 [ 2] 1.6/12/260 RENO Korea 0.150/20/ /20/675

46 Diapositiva 44 h2 hepvb, 19/09/2005

47 Comparison with other ν Reactor experiments Reactor Optimistic start date GW t yr (yr) Sin 2 2θ sensitivity for m 2 (10 3 ev 2 ) Efficiencies Far event rate ANGRA 2013(full) 3900(1) 9000(3) 15000(5) ,000/yr Braidwood (1) 2535(3) 7605(9) ,000/yr Daya Bay 08(fast) 09(full) 3700(3) ,000/yr 110,000/yr (before/after 2010) Double Chooz Oct 07(far) Oct 08(near) 29(1) 29(1+1) 80(1+3) ,000/yr KASKA Mar (3) ,000/yr RENO Late (1) ,000/yr

48 Institutional Responsibilities Experimental Groups construction operation ELETRONUCLEAR approval Communication established! CNEN regulatory submission Support from CNEN and ELETRONUCLEAR Support from CNEN and ELETRONUCLEAR CNEN (Comissão Nacional de Energia Nuclear) ELETRONUCLEAR (company operating the plant)

49 Motivations for the Angra Experiment Interaction with Industry Área de microeletrônica: desenvolvimento de circuitos para o trigger de múons que serão usados em Angra e Double Chooz: encomendas à indústria Mecânica pesada: construção do vaso do detector e estruturas de suporte Construção civil: construção de laboratório subterrâneo para instalação do detector

50 Next Steps Geological survey Eletronuclear will help to perform the study Simulations for Detector design: 2 vs. 3 zones Calibration requirements Prototype Site Proposal for testing scintillator and detector development submitted Necessary to understand background effects possible prototype location discussed with Eletronuclear: 66m from reactor

51 Protoype Detector Test of detector components and Performance studies Geometry, PMT s, scintillators, electronics, backgrounds Understand systematic errors Special Bonus: Neutrino Applied Physics! Nuclear safeguards monitoring for non proliferation of nuclear weapons

52 non-proliferation

53 non-proliferation (of nuclear fissile material)

54 Neutrino Detectors: a new safeguards tool? Antineutrinos have very small interaction cross section, so they easily escape from a reactor ( they cannot be blocked! ). Nuclear reactors are powerful sources of antineutrinos Antineutrinos interact feebly, so detectors need to be big and close to reactor

55 Non intrusive method to monitor reactor activity Reactor core Flux of antineutrinos Antineutrino detector

56 Reactor Monitoring Remote, Integral Continuous Real time Non intrusive Unattended

57 Reactor Monitoring Antineutrinos have specific energy spectrum that varies depending on the reactor fuel composition. Rate and energy spectrum are sensitive to the fissile content of the core (fuel composition). Real data and detailed reactor simulations show a reduction in the antineutrino rate of about 12% through a 600 day cycle - caused by Pu ingrowth and U fission kg of new plutonium is generated in a typical cycle. IAEA and reactor operators the principal customers Counting rate of a detector linearly depends on the reactor power N ν ~ γw th

58 Safeguards Applications A mission of IAEA (International Atomic Energy Agency) : Safeguard & Verification: control that member states do not use civil installations with military goals (e.g. production of plutonium). Neutrino detector can track unauthorized production of plutonium outside of declarations IAEA interested in the use of neutrino detectors for nuclear reactor monitoring. Recommended a feasibility study on neutrinos. (Meeting with USA, France, Russia authorities in Viena in 2002). Cost problem: inspector::us$ /day. One such a detector already in operation: SANDS

59 SANDS: Safeguards AntiNeutrino Detector System Sandia & Lawrence Livermore National Laboratories in the San Onofre Nuclear Generation Station

60 An Experimental Test at a Reactor Site 25 meters standoff from core 20 meter overburden San Onofre Nuclear Generating Station Unit II 3.46 GWt

61 How Does The IAEA Monitor Fissile Material Now? (1 1.5 years) (months to years) (months) (forever) 1. Check Input and Output Declarations 2. Verify with Item Accountancy 3.Containment and Surveillance 1 Gross Defect Detection 2 Continue Item Accountancy 3. Containment and Surveillance 1 Check Declarations 2 Verify with Bulk Accountancy: Operators Report Fuel Burnup and Power History No Direct Pu Inventory Measurement is Made Unless and Until Fuel is Reprocessed

62 Safeguards Verification Determination of Isotopic Composition of the Spent Fuel is based on the comparison of Simulations (of Initial Composition + Thermal History) and Inventory of Final Composition. Based on Reactor Operator Declarations

63 Non-proliferation effort Short-Term Goals Perform antineutrino spectrum measurement at Angra Use Very Near Detector as the Prototype for nuclear reactor monitoring Collaboration with Los Alamos, Livermore, Sandia, DoubleChooz, Byproduct for industry: measurement of thermal precision

64 The safeguards detector 50 m selected possible localizations

65 Measure: Burn up ( 239 Pu accumulation) Thermal power

66 Antineutrino Detectors Have Potential Advantages for Reactor Safeguards This approach provides real time thermal power measurements and Bulk Accountancy of plutonium at the earliest possible moment in the regime Antineutrino detection might replace or complement current techniques, or provide a new capability

67 Monitoring Reactors with Antineutrino Detectors Cubic meter active volume detector a few tens of meters from reactor core Compare measured and predicted total daily or weekly antineutrino rates (or spectrum) to search for anomalous changes in the total fission rate Identify changes in fissile content based on changes in antineutrino rate (the burnup effect). Measured in several previous experiments

68 Concept of Operation: Track Power and Changes in Plutonium Loading Through the Antineutrino Rate Predicted daily antineutrino count rate (% of rate at startup) 100% of rate 90 95% of rate Reactor power is proportional to count rate with known fuel loading/geometry shutdown startup days The systematic shift in plutonium inventory is reflected by the changing antineutrino count rate over time Typically there is a 2 3% systematic drop in antineutrino count rate over 6 months

69 Large amounts of antineutrinos from beta decays of fission products Emission Spectra for different fissile materials

70 Burn up effect on fuel composition

71 Antineutrino Rate Varies with Time and Isotope Fuel Composition Antineutrino Fission Rate varies with Isotope Relative Fission Rate vary in Time Pu 241 U 238

72 The Basic Idea A. Monitor operating reactors with ~1 m 3 antineutrino detectors placed a few tens of meters from the reactor core B. Compare measured and predicted antineutrino rate or spectra to identify changes in fissile content. Pu 241 U 238 Antineutrino count rate relative to beginning of cycle Full power days

73 How Does it Work Operationally? The systematic shift in inventory is reflected in the changing antineutrino count rate over time

74 Daily Power Monitoring Using Only Antineutrinos Antineutrino counts per day /23/05 2/27/05 3/3/05 3/7/05 3/11/05 3/15/05 3/19/05 Date Predicted count rate using reported reactor power Observed count rate, 24 hour average Reported reactor power Reactor Power (%)

75 Some experiments to monitor nuclear reactors with neutrino detectors: Rovno ( ), Bugey (1994) San-Onofre (2004) Chooz (2002?)

76 Some Previous and Ongoing experiments Rovno (Ukraine) San Onofre (USA)

77 Some previous and Ongoing experiments (cont ): Rovno San Onofre 1050 liters of liquid scintillator on mineral oil base g/l Gd, central volume 510 liters 84 PMTs 1 m 3 Liquid scintillator central detector (Gd loaded) 8 PMTs on top side of 4 tanks Passive water shield + Active muon shield

78 Successful checkings of reactor activity: A n tin e u trin o c o u n ts p e r d a y /23/05 2/27/05 3/3/05 3/7/05 3/11/05 3/15/05 3/19/05 Date Predicted count rate using reported reactor power Observed count rate, 24 hour average Reported reactor power R e a c to r P o w e r (% ) Rovno (Ukraine) San Onofre (USA)

79 Reactor Thermal Power and Antineutrino flux Relation between reactor thermal power and antineutrino flux: N ν = γ (1 + k) P th Dependence on detector features Dependence on fuel composition

80 Remarks (safeguards) Previous experiments demonstrate a good capability of using Antineutrinos for Nuclear reactor distant monitoring. Uncertainty of thermal power measurement can be decreased by accounting fuel composition.

81 Some International Contacts France Thierry Lasserre CEA/Saclay Double Chooz and AIEA safeguards Italy Walter Fulgione INFN (Torino) Liquid Scintillator doped with Gd, R&D detector USA. David Reyna Argonne Nat Lab Background studies, Detector Design, R&D Adam Bernstein Lawrence Livermore Nat Lab Prototype Design and R&D Nathaniel Bowden Sandia Nat Lab open

82 Concluding Remarks Fase I Prototype Detector: To develop neutrino detection techniques in Latin America To develop novel technique for nuclear reactor monitoring Science development in Latin America Industry involvement Internacional collaboration with IAEA, ABACC and research labs in USA, France, Italy, Germany and Argentina. ABACC:Agencia Brasileiro Argentina de Contabilidade e Controle de Materiais Nucleares

83 ABACC + ANGRA Project ASSESSMENT of the TECHNICQUE + IAEA!

84 Conclusions fase II: Experimental Reach of the Angra Project Até o momento só limite superior para ângulo de mistura θ 13 foi medido pelo experimento de reator nuclear Chooz na França: sin 2 (2 θ 13 ) < 0.2 O experimento de Angra será capaz de alcançar uma sensitividade ao desaparecimento dos antineutrinos da ordem de sin 2 (2 θ 13 ) = Angra poderá melhorar o limite estabelecido por Chooz por mais de uma ordem de grandeza! Com o conhecimento de θ 13 será possível medir o parametro δ de violação de CP no setor leptônico (se θ13 0), talvez a chave para entender a assimetria matéria antimatéria no universo!

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