Neutrino detectors - Daya Bay Reactor Neutrino Experiment

Report
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
– mn0  mn(ne) ~ 10-19 mB
Bohr magneton
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:
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 85m105m4
= 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)
[email protected]
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
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 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
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.

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