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Overview of neutrino experiment in the Daya Bay era

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Overview of neutrino experiment in the Daya Bay era Powered By Docstoc
					Neutrino detectors:
 Present and Future
          Yifang Wang
Institute of high energy physics
Neutrino industry
   Neutrino physics:problems and methods
                                                 Oscillation
                   Dirac/        Magnetic        /sterile
   Mass                                                         Astronomy Cosmology Geology
                   Majorana      moments         neutrinos




Radioactive                                   Atmos-               Astro-    Relic-
                   Reactor Accelerator                  Solar                             Earth
sources                                       pheric               objects   neutrino




Semiconductor/        Liquid         Liquid                              Water          Nuclear
                                                 Sampling Emulsion
crystals/gaseous      scintillator   Argon       detector                Cerenkov       chemistry
/scintillator
                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                  Bohr magneton
   – mn0  mn(ne) ~ 10-19 mB           mB = eh / 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:
   – 1/T excess in n-e scattering
                                   1kg ULB-HPGe
                                   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                     Current status:
   – Reduce the cost to < ~kg/30K $ ?                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 @ 90%CL:
Sensitivity increase with area                      m(n) < 0.2 eV
Low statistics for relevant events                  Last such exp. ?
Resolution: ~ 1 eV
             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               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
              phase I: DE = 15 eV, mn < 2 eV
   Mare:      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)                               Phase I
• R&D on sensor-
  absorber couplings,
  pixel design, readout,
  systematics
  assessment, etc.                                Phase II
• Need:
   – Higher mass
   – Lower backgrounds
   – Better energy
     resolution
    Neutrino oscillation experiments

Technologies                     Experiments
• Water Cerenkov detector        • Atmospheric neutrino exp.
                                    – SuperK,HyperK/UNO,
• Liquid Ar TPC                       INO,TITAND,…
• Liquid Scintillator detector   • Solar neutrino exp.
• Sampling detectors for            – GALLEX/SAGE, SNO, Borexino,
                                      XMASS, …
  neutrino beams
                                 • 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 85m105m4
                                  = 3 Mt (2.2 Mt FV)
                                  TITAND-II
                                  4 modules  8.8 Mt
                                  (400  SK)
                 GADZOOKS & EGADS
• Gd in water:                           ne + p  e+ + n
   – GdCl3 highly soluble in water
   – Improve low energy detection        n + p  d + g (2.2 MeV)
     capabilities                        n + Gd  Gd* + g (8 MeV)
   – flavor sensitive                         t  28 ms(0.1% Gd)
   – Good for LBNE, supernova, reactor
     and geo-neutrinos, …
• A 200 ton-scale R&D project,
  EGADS – is under construction at
  Kamioka
                      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
    Successful R&D in Europe, Japan & US




                         Drift time coordinate (1.4 m)
ArgoNeut event in NuMI                                                       CNGS nm CC events in ICARUS T600
                                                           Collection view




                                                         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
• 220kt cryostat
• Maximum drift
  length: 2.5 m
   (1.4 ms)
• 645000
  readout wires
  (128:1 MUX)
• 3mm Wire
  pitch
                         Liquid Argon: other proposals
    o        In Japan: 100kt for JPARK 
             Okinoshima
    o        In Europe: Modular and Glacier
             o     Modular:
                    – 20 kton proposal at LNGS based
                      on larger 8x8 m2 ICARUS modules
             o     Glacier:
                    – 50-100 kton, Readout: Large
                      GEMs (LEM)
 Charge readout
 plane
 (LEM plane)
                                    GAr
                          E ≈ 3 kV/cm

                                                            Electron
Extraction                                                  ic
                           field




grid                                                        racks
                 LAr
                           E-




                     E≈ 1 kV/cm                              Field shaping
                                                             electrodes

  Cathode (- HV)              UV & Cerenkov light readout
                              PMTs
              LBNE: LAr or Water ?
LAr                             Water
• Pros                          • Pros
  – Beautiful image of events     – Proven technology
  – Good energy resolution        – Cost under control
  – Good PID and pattern          – Good energy resolution
    recognition                     (slight worse)
  – High efficiency               – Good PID & pattern
  – Requiring smaller cavern        recognition, particularly
    and shallow depth               at low energies
• Cons                          • Cons
  – Technology for such a         – Lower efficiency
    volume ?                      – Larger cavern and deep
  – Huge No. of channels            underground
  – Cost ?
         Liquid scintillator detectors
• Successful for reactor and geo-
  neutrinos
• Current benchmark:
   –   Mass: 1 kt             KamLAND
   –   Gd-loading LS: ~200t     Daya Bay
   –   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      Quantity(t)
                                        compound
     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
                                   Gadolinium    Trimethylhe      Linear Alky
• Chemical procedures              Choloride     mxanoic Acid     Benzene                              Fluor


• Procurement of high quality       GdCl3         TMHA              LAB                          PPO, bis-MSB

  materials & Purification of
  PPO/Gdcl3/TMHA                     Gd (TMHA)3

• Gd-compound production &                                                                       LS
                                                Gd-LAB
  Gd-LS production
                                                                0.1% Gd-LS




                                                                    good quality and stability




 Gd-LS production Equipment
 tested at IHEP, used at Dayabay
          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
                           Daya Bay II For
LENA For
                           Mass hierarchy
Supernova
                           Precision
geo-neutrinos
                           mixing matrix
Proton decays
                           elements
LBNE
                           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                   Linear- Alkyl- Benzene
• How to improve ? Take the 2-grediants               (C6H5 -R)
  solution LAB + fluor as an example :
   – Use quantum chemistry calculations to identify      R&D effort by IHEP
     structures which absorb visible and UV light        & Nanjing Uni.
   – Study removing method




                                                                       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
                                                 5”MCP-PMT
         ~ 2 improvement on QE                  made in China

                                  Photocathode



                                       MCP


                                        Anode


                                                 Test results:
                                                   Gain: (1-5)105
                                Photocathode       Noise: < 10 nA
R&D effort by Y.F. Wang et al                      QE ~ (15-20)%
    Sampling detectors for neutrino beams
• Absorber: Pb, Fe, …                       T2K near

• 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                                         NOVA
 1.25 kt                                       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 161614.4m3
                                            150 iron plates, each 5.6 cm thick
      A Magnetized Iron Neutrino Detector for
       SuperBeams/neutrino factories(MIND)
• Goal: CP phase  appearance                      50-100 m
  of “wrong-sign” muons in                                           15 m
  magnetised iron calorimeter
                                n beam
• A generic detector simulation                 50-100kT              15 m
  and R&D, Baseline assumed
  2000-7500 km                    B=1 T
• Detector benchmark:                     iron (3 cm) + scintillators (2cm)
   – 50-100 kt Far detector
• Features:
   – Segmentation: 3 cm Fe + 2 cm
     extruded scintillator + WLS
     fiber + SiPM
   – 1 T toroidal magnetic field
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.

				
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posted:11/19/2012
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