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Neutrino detectors: Present and Future

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1 Neutrino detectors: Present and Future
Yifang Wang Institute of high energy physics

2 Neutrino industry

3 Neutrino physics:problems and methods
Mass Geology Astronomy Dirac/ Majorana Oscillation /sterile neutrinos Magnetic moments Cosmology Reactor Earth Solar Atmos-pheric Accelerator Radioactive sources Astro-objects Relic-neutrino Liquid scintillator Semiconductor/crystals/gaseous/scintillator Emulsion Nuclear chemistry Water Cerenkov Sampling detector Liquid Argon

4 Selected topics Personnel flavors Mainly on neutrino oscillations
Present experimental techniques with future prospects Future trends I apologize for incompleteness, bias and mis-handling

5 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)

6 Neutrino magnetic moments
SM: mn=0  mn(ne) = 0 mn0  mn(ne) ~ mB Non-SM: mn(ne) ~ mB Astrophysics limit(model dependent) He star, White dwarf, SN 1987 A, Solar(SuperK, KamLAND, Borexino), … Direct searches: 1/T excess in n-e scattering Bohr magneton B = eh / 2 me TEXONO 1kg ULB-HPGe Background level: ~ 1/(day kg KeV) Threshold: ~ 10 KeV Limit: mn(ne) < 1.3  mB (90% CL)

7 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]

8 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: 1.33MeV Working on stability & repeatability

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

10 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 90%CL: m(n) < 0.2 eV Last such exp. ?

11 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: Detect the RF signal Understand the resolution Measure the energy spectrum of 83m Kr

12 Mare: Bolometer Bolometer: DT = E/C
Similar Techniques used also in bb decay and dark matter searches 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

13 Mare: Sensitivity increase with volume:
phase I: DE = 15 eV, mn < 2 eV phase II: DE = 5 eV, mn < 0.2 eV Mare: Sensitivity increase with volume: Arrays of mg-sensors Up to kg for sub-eV m(n) R&D on sensor-absorber couplings, pixel design, readout, systematics assessment, etc. Need: Higher mass Lower backgrounds Better energy resolution Phase I Phase II

14 Neutrino oscillation experiments
Technologies Experiments Water Cerenkov detector Liquid Ar TPC Liquid Scintillator detector Sampling detectors for neutrino beams Atmospheric neutrino exp. 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,…

15 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

16 Future: LBNE water option
Module spec.: Total water mass: 138 kt Fiducial mass: 100 kt ” 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

17 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

18 Physics reach Performance Similar for 30kt liquid Ar TPC

19 Even larger water detectors for LBNE, proton decays and supernova
500 kton Deep-TITAND (10 Mt) TITAND-I 85m 85m105m4 = 3 Mt (2.2 Mt FV) TITAND-II 4 modules  8.8 Mt (400  SK)

20 GADZOOKS & EGADS ne + p  e+ + n 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)

21 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

22 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 Digital bubble chamber: Excellent for discoveries, say ne appearance m decay at rest Time Drift direction Edrift ~ 500 V/cm m.i.p. ionization ~ 6000 e-/mm Scintillation light yield nm

23 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 Lessons learned: Impurities (O2, H2O, CO2) should be < 0.1 ppb O2 equivalent 3 ms lifetime (4.5m Edrift = 500 V/cm) Two recirculation/purification scheme: Gas & liquid phase 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)

24 Successful R&D in Europe, Japan & US
Collection view Wire coordinate (8 m) Drift time coordinate (1.4 m) ArgoNeut event in NuMI CNGS nm CC events in ICARUS T600

25 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

26 Future: LBNE LAr option
220kt cryostat Maximum drift length: 2.5 m  (1.4 ms) readout wires (128:1 MUX) 3mm Wire pitch

27 Liquid Argon: other proposals
In Japan: 100kt for JPARK  Okinoshima In Europe: Modular and Glacier Modular: 20 kton proposal at LNGS based on larger 8x8 m2 ICARUS modules Glacier: kton, Readout: Large GEMs (LEM) LAr Cathode (- HV) E-field Extraction grid Charge readout plane (LEM plane) UV & Cerenkov light readout PMTs E≈ 1 kV/cm E ≈ 3 kV/cm Electronic racks Field shaping electrodes GAr

28 LBNE: LAr or Water ? LAr Water Pros Cons Pros Cons
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 ? Pros 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

29 Liquid scintillator detectors
Successful for reactor and geo-neutrinos Current benchmark: Mass: 1 kt Gd-loading LS: ~200t Threshold: ( ) MeV 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 KamLAND Daya Bay Borexino

30 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 Daya Bay 185

31 Gd-Loaded LS production at Daya Bay
GdCl3 TMHA PPO, bis-MSB LAB Gd (TMHA)3 Gd-LAB LS 0.1% Gd-LS Gadolinium Choloride Trimethylhemxanoic Acid Linear Alky Benzene Fluor Chemical procedures Procurement of high quality materials & Purification of PPO/Gdcl3/TMHA Gd-compound production & Gd-LS production good quality and stability Gd-LS production Equipment tested at IHEP, used at Dayabay

32 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

33 Scintillator purification: Borexino
Target for pp solar neutrinos, background is the key Water extraction Vacuum distillation Filtration Nitrogen stripping

34 Future: ~50kt Liquid Scintillator
Daya Bay II For Mass hierarchy Precision mixing matrix elements Supernova geo-neutrinos LENA For Supernova geo-neutrinos Proton decays LBNE Hanohano For Supernova geo-neutrinos Proton decays LBNE

35 The Daya Bay II project Other main Scientific goals:
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

36 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 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.

37 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.

38 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 5”MCP-PMT made in China ~ 2 improvement on QE Photocathode Anode MCP Test results: Gain: (1-5)105 Noise: < 10 nA QE ~ (15-20)% R&D effort by Y.F. Wang et al

39 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 T2K near OPERA 1.25 kt NOVA 25 kt

40 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 161614.4m3 150 iron plates, each 5.6 cm thick

41 A Magnetized Iron Neutrino Detector for SuperBeams/neutrino factories(MIND)
Goal: CP phase  appearance of “wrong-sign” muons in magnetised iron calorimeter A generic detector simulation and R&D, Baseline assumed km Detector benchmark: kt Far detector Features: Segmentation: 3 cm Fe + 2 cm extruded scintillator + WLS fiber + SiPM 1 T toroidal magnetic field iron (3 cm) + scintillators (2cm) n beam 15 m B=1 T 50-100kT m

42 Physics reach: ultimate dream

43 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

44 Thanks 谢谢 Acknowledgements
Many Information & slides from relevant talks given at NuFact2010, Neutrino 2010, WIN11, NeuTEL 2011, etc.


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