Neutrino detectors - Daya Bay Reactor Neutrino Experiment
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Neutrino detectors： Present and Future Yifang Wang Institute of high energy physics Neutrino industry Neutrino physics：problems and methods Mass Radioactive sources Semiconductor/ crystals/gaseous /scintillator Dirac/ Majorana Magnetic moments Reactor Accelerator Liquid scintillator Liquid Argon Oscillation /sterile neutrinos Atmospheric Solar Astronomy Cosmology Geology Astroobjects Sampling Emulsion detector Relicneutrino Water Cerenkov Earth Nuclear chemistry Selected topics • Personnel flavors • Mainly on neutrino oscillations • Present experimental techniques with future prospects • Future trends I apologize for incompleteness, bias and mis-handling Selected Neutrino Experiments • Basic properties of neutrinos – Magnetic moments: Texono, GEMMA, … – Absolute mass: Katrin, Mare, Project 8, … • Neutrino oscillations & sterile neutrinos – Atmospheric neutrinos(q23): SuperK, INO … – Solar neutrinos(q12): SuperK, SNO, Borexino, … – Reactor neutrinos(q12,q13): KamLAND, Daya Bay, Double CHOOZ, Reno,… mass hierarchy – Accelerator neutrinos(q23,q13): MINOS, OPERA, MiniBooNe, T2K, NOVA,… mass hierarchy, d, … • Neutrino astronomy & applications – – – – Supernova in combination with solar/atmospheric/reactor neutrinos Geo-neutrinos in combination with solar/reactor neutrinos High energy neutrinos(not covered in this talk) … Neutrino magnetic moments • SM: – mn=0 mn(ne) = 0 – mn0 mn(ne) ~ 10-19 mB Bohr magneton mB = eh / 2 me • Non-SM： – mn(ne) ~ 10-10-14 mB • Astrophysics limit(model dependent) – He star, White dwarf, SN 1987 A, Solar(SuperK, KamLAND, Borexino), … TEXONO • Direct searches: 1kg ULB-HPGe – 1/T excess in n-e scattering Background level: ~ 1/(day kg KeV) Threshold: ~ 10 KeV Limit: mn(ne) < 1.3 10-10 mB (90% CL) GEMMA • 1.5 kg HPGe installed within NaI active shielding. • Multi-layer passive shielding : electrolytic copper, borated polyethylene and lead • More HpGe, better shielding Another fact of 10 ? [Phys. of At. Nucl.,67(2004)1948] Ultra-pure Ge detectors • Common technology for bb decays, dark matter… • Future advances: – Mass: ~100 kg 1000 kg ? – Threshold: ~10 keV 1 keV ? – Cost: ~ kg/300K $ ~kg/30K $ ? • Efforts in China(Shenzhen U. & Tsinghua U.) to: – Reach the impurity to 10-13 – Reduce the cost to < ~kg/30K $ ? Current status: impurity ~ 10-11/cm3 Resolution: 1.76KeV @ 1.33MeV Working on stability & repeatability 载流子浓度(1/cm^3) 1.000E+12 1.000E+11 1.000E+10 2.0cm 8.8cm 15.6cm 22.4cm 29.2cm 36cm 42.8cm 47.6cm 54.4cm 1 2 3 4 5 6 7 8 9 Absolute Neutrino mass：b decays • Requirement: – Source: • Low endpoint • High event rate – appropriate lifetime – Enough source material (thickness affect b spectrum) – Detector: • High resolution • Low background • Experiments: – Source detector: Katrin, Project 8 – Source = detector: Mare Katrin: b spectrometer T1/2 = 12.3 y Magnetic Adiabatic Collimation + Electrostatic Filter A large spectrometer： Sensitivity increase with area Low statistics for relevant events Resolution: ~ 1 eV Sensitivity @ 90%CL: m(n) < 0.2 eV Last such exp. ? Project 8: Radio Frequency • Electrons moving in a uniform magnetic field emit cyclotron radiation: • Advantages: – Non-destructive measurement of Frequency energy – Resolution improves over time Dw 1/T 1 eV – Target mass scales with volume – Promising for m(n) < 0.1 eV • Challenges: – Unknown systematics R&D: 1) Detect the RF signal 2) Understand the resolution 3) Measure the energy spectrum of 83m Kr Mare： Bolometer • Bolometer: DT = E/C – Phonons: C ~ T3 (Debye law) at T<< 1K – Event time: DT = E/C e-t/(C/G) – Resolution：sE = (kBT2C)1/2 Similar Techniques used also in bb decay and dark matter searches Mare: phase I: DE = 15 eV, mn < 2 eV phase II: DE = 5 eV, mn < 0.2 eV • Sensitivity increase with volume: – Arrays of mg-sensors – Up to kg for sub-eV m(n) • R&D on sensorabsorber couplings, pixel design, readout, systematics assessment, etc. • Need: – Higher mass – Lower backgrounds – Better energy resolution Phase I Phase II Neutrino oscillation experiments Technologies Experiments • • • • • Atmospheric neutrino exp. Water Cerenkov detector Liquid Ar TPC Liquid Scintillator detector Sampling detectors for neutrino beams • … – SuperK，HyperK/UNO，INO， TITAND,… • Solar neutrino exp. – GALLEX/SAGE, SNO, Borexino, XMASS, … • Accelerator neutrino exp. – Minos, OPERA, MiniBooNE, T2K, Nova, … • Reactor neutrino exp. – KamLAND, Daya Bay, Reno, Double Chooz,… Water Cerenkov detectors • Successful for atmospheric neutrinos, proton decays, supernova, … • Current benchmark set by SuperK: – – – – Mass: 50 kt PMT coverage: ~40% Threshold: ~4 MeV Light yield: 6 PE/MeV • Future ~Mt detector for – Very long baseline neutrino exp. – Proton decays/supernova Future: LBNE water option • Module spec.: – – – – – – Total water mass: 138 kt Fiducial mass: 100 kt 50000 10” PMT PMT Coverage: 20% Light yield: 3 PE/MeV Threshold: 6MeV • Performance for single rings – Energy resolution: 4.5%/E – vertex resolution: 30cm – Good e/m separation • Multi-rings – Pattern recognition – Event reconstruction 2 100 kt Modules Technical issues • PMT: under pressure (60m ~ 0.7 Mpa) ? • Water circulation system: – Requirement: Attenuation length > 80 m – Volume: 100 days to fill, > 20 days to circulate 1 volume • Civil – A cavern of 55m diameter, 70m high Not trivial but also not impossible Physics reach Performance Similar for 30kt liquid Ar TPC Even larger water detectors for LBNE, proton decays and supernova 500 kton Deep-TITAND (10 Mt) TITAND-I 85m 85m105m4 = 3 Mt （2.2 Mt FV) TITAND-II 4 modules 8.8 Mt (400 SK) GADZOOKS & EGADS • Gd in water: – GdCl3 highly soluble in water – Improve low energy detection capabilities – flavor sensitive – Good for LBNE, supernova, reactor and geo-neutrinos, … • A 200 ton-scale R&D project, EGADS – is under construction at Kamioka ne + p e+ + n n + p d + g (2.2 MeV) n + Gd Gd* + g (8 MeV) t 28 ms(0.1% Gd) Exotic ideas for LBNE • Water Cerenkov Calorimeter: – Segmented modules 1 1 10 m3 – two PMTs at each end – Pattern recognition similar to crystal calorimeter Y.F. Wang , NIM. A503(2003)141 M.J. Chen et al., NIM. A562 (2006)214 Liquid Ar TPC: another detector candidate for LBNE • Idea first proposed in 1985 – Dense target – ample Ionization & scintillation: good energy resolution & Low threshold – Excellent tracking and PID capabilities m decay at rest • Digital bubble chamber: – Excellent for discoveries, say ne appearance m.i.p. ionization ~ 6000 e-/mm Time Scintillation light yield 5000 γ/mm @ 128 nm Drift direction Edrift ~ 500 V/cm ICARUS • Successful After 20 years R&D • Excellent performance – Tracking: sx,y ~ 1mm, sz ~ 0.4mm – dE/dx: 2.1 MeV/cm – PID by dE/dx vs range – Total energy by charge integration Low energy electrons: σ(E)/E = 11% / √E(MeV)+2% Electromagnetic showers: σ(E)/E = 3% / √E(GeV) Hadron shower (pure LAr): σ(E)/E ≈ 30% / √E(GeV) • Lessons learned: Impurities (O2, H2O, CO2) should be < 0.1 ppb O2 equivalent 3 ms lifetime (4.5m drift @ Edrift = 500 V/cm) • Two recirculation/purification scheme: Gas & liquid phase ArgoNeut event in NuMI Drift time coordinate (1.4 m) Successful R&D in Europe, Japan & US Collection view CNGS nm CC events in ICARUS T600 Wire coordinate (8 m) 250L@KEK R&D towards LBNE & MicroBooNE • R&D efforts and technical challenges – Long-drift operations(LAr purity) – Membrane cryostat for multi-kiloton TPC – Readout wires or Large electron Multipliers – Cold electronics • MicroBooNE: Combine R&D with physics A ~100t LAr TPC at Fermilab on-axis Booster beam and off-axis NuMI beam for – MiniBooNE low energy excess – Low energy cross sections Future: LBNE LAr option • 220kt cryostat • Maximum drift length: 2.5 m (1.4 ms) • 645000 readout wires (128:1 MUX) • 3mm Wire pitch Liquid Argon: other proposals o o In Japan: 100kt for JPARK Okinoshima In Europe: Modular and Glacier Modular: o – 20 kton proposal at LNGS based on larger 8x8 m2 ICARUS modules Glacier: o – 50-100 kton, Readout: Large GEMs (LEM) Charge readout plane (LEM plane) GAr Extraction grid LAr Efield E ≈ 3 kV/cm E≈ 1 kV/cm Cathode (- HV) UV & Cerenkov light readout PMTs Electron ic racks Field shaping electrodes LBNE: LAr or Water ？ LAr Water • Pros • Pros – Beautiful image of events – Good energy resolution – Good PID and pattern recognition – High efficiency – Requiring smaller cavern and shallow depth • Cons – Technology for such a volume ? – Huge No. of channels – Cost ? – Proven technology – Cost under control – Good energy resolution (slight worse) – Good PID & pattern recognition, particularly at low energies • Cons – Lower efficiency – Larger cavern and deep underground Liquid scintillator detectors • Successful for reactor and geoneutrinos • Current benchmark: – – – – – KamLAND Mass: 1 kt Daya Bay Gd-loading LS: ~200t Threshold: (0.1-0.3) MeV Borexino Light yield: ~500 PE/MeV PMT coverage: up to 80% • Future (10-50)t detector for – – – – LBNE Supernova/geo-neutrinos Mass hierarchy Precision mixing matrix elements Liquid scintillator: a mature technology • What we care: light yield, transparency, aging, … • Traditionally 3-grediants, say: – Pseudocumene+MO+fluors – But PC suffer from Low flush point, Chemical attacks, High cost, … • Recently 2-grediants, say: LAB + flour • Even more difficult, load metallic elements, Gd, Nd, In, … into the liquid, Known difficult to be stable Currently produced Gd-loaded liquid scintillators Groups Solvent Complexant for Gd compound Quantity(t) Chooz IPB alcohol 5 Palo Verde PC+MO EHA 12 Double Chooz PXE+dodecane Beta-Dikotonates 40 Reno LAB TMHV 40 Daya Bay LAB TMHV 185 Gd-Loaded LS production at Daya Bay • Chemical procedures • Procurement of high quality materials & Purification of PPO/Gdcl3/TMHA • Gd-compound production & Gd-LS production Gadolinium Choloride Trimethylhe mxanoic Acid Linear Alky Benzene GdCl3 TMHA LAB PPO, bis-MSB Gd (TMHA)3 LS Gd-LAB 0.1% Gd-LS good quality and stability Gd-LS production Equipment tested at IHEP, used at Dayabay Fluor Precision: Daya Bay Experiment • Systematic errors < 0.4% • Multiple detector modules + multiple vetos redundancy • Near site data taking this summer, full data taking next summer Scintillator purification: Borexino Target for pp solar neutrinos, background is the key Water extraction Vacuum distillation Filtration Nitrogen stripping Future: ~50kt Liquid Scintillator LENA For Supernova geo-neutrinos Proton decays LBNE Daya Bay II For Mass hierarchy Precision mixing matrix elements Supernova geo-neutrinos Hanohano For Supernova geo-neutrinos Proton decays LBNE The Daya Bay II project Daya Bay Daya Bay II Effects of mass hierarchy can be seen from the reactor neutrino energy spectrum after a Fourier transformation Other main Scientific goals: Mixing matrix elements Supernovae/geo-neutrinos L. Zhan et al., PRD78:111103,2008 L. Zhan et. al., PRD79:073007,2009 Technical challenges：liquid scintillator • A typical detector design(R~30m) requires the scintillator attenuation length > 30m • But typical attenuation length of bulk scintillator materials is 10-20 m • How to improve ? Take the 2-grediants solution LAB + fluor as an example : – Use quantum chemistry calculations to identify structures which absorb visible and UV light – Study removing method Linear- Alkyl- Benzene (C6H5 -R) R&D effort by IHEP & Nanjing Uni. 36 A common issue: photo detection for large water/scintillator/LAr detectors low cost, single PE, low background,… • Large area, low cost MCP •All (cheap) glass •Anode is silk-screened R&D project by Henry Frisch et al. Other ideas: high QE PMTs 20” UBA/SBA photocathode PMT from Hamamatzu ? New ideas: Top: transmitted photocathode Bottom: reflective photocathode additional QE: ~ 80%*40% MCP to replace Dynodes no blocking of photons ~ 2 improvement on QE 5”MCP-PMT made in China Photocathode MCP Anode Test results: Photocathode R&D effort by Y.F. Wang et al Gain: (1-5)105 Noise: < 10 nA QE ~ (15-20)% Sampling detectors for neutrino beams • Absorber: Pb, Fe, … • Sensitive detectors: Emulsion Films(OPERA), Plastic(MINOS) and Liquid(NOVA) Scintillators, RPC(INO), … • Near detector issues: hybrid detector system to monitor neutrino/muon flux & beam profile OPERA 1.25 kt T2K near NOVA 25 kt Indian Neutrino observatory: INO • 50kt magnetized iron plate interleaved by RPC for – Sign sensitive atmospheric neutrinos (stage I) – long baseline neutrino beams – (stage II) • Features: – Far detector at magic baselines: ̶ CERN to INO: 7152 km ̶ JPARC to INO: 6556 km ̶ RAL to INO: 7653 km – Muons fully contained up to 20 GeV – Good charge resolution, B=1.5 T – Good tracking/Energy/time resolution three 17kt modules, each 161614.4m3 150 iron plates, each 5.6 cm thick A Magnetized Iron Neutrino Detector for SuperBeams/neutrino factories(MIND) • Goal: CP phase appearance of “wrong-sign” muons in magnetised iron calorimeter n beam • A generic detector simulation and R&D, Baseline assumed 2000-7500 km B=1 T • Detector benchmark: – 50-100 kt Far detector • Features: – Segmentation: 3 cm Fe + 2 cm extruded scintillator + WLS fiber + SiPM – 1 T toroidal magnetic field 50-100 m 50-100kT 15 m 15 m iron (3 cm) + scintillators (2cm) Physics reach: ultimate dream Summary • No significant advances of neutrino physics since the discovery of neutrino oscillation waiting for q13 • A lot of technological progress preparation for the next generation experiments – larger mass: typically a factor of 10 for all the techniques – Better resolution, precision, signal to background ratio etc – Innovative ideas • New discoveries ahead of us Thanks 谢谢 Acknowledgements Many Information & slides from relevant talks given at NuFact2010, Neutrino 2010, WIN11, NeuTEL 2011, etc.
