Scintillator Detectors for Neutrino Physics Minfang Yeh Neutrino and Nuclear Chemistry, BNL Jinping Workshop, Tsinghua, June 5, 2015
Scintillator Detectors for Neutrino Physics
Minfang YehNeutrino and Nuclear Chemistry, BNL
Jinping Workshop, Tsinghua, June 5, 2015
BNL-Liquid Scintillator Development Facility
• A unique facility (since 2002) for Radiochemical, Cherenkov, and Scintillator (water-based and metal-doped) detectors for particle physics experiments.
• Daya Bay, SNO+, PROSPECT, LZ, WATCHMAN, THEIA (ASDC)• Institutional collaboration welcome!
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Cherenkov (Gd): e.g. SK, SNO, WATCHMAN-I, HK
Scintillator: e.g Daya Bay, D-Chooz, RENO, JUNO
Cherenkov and Scintillator Detector
Water-based Liquid ScintillatorWater-Like WbLS• Cher/Scin det.
Oil-Like WbLS• Isotope loading
PROSPECT, SNO+, WATCHMAN-II, Theia
M. Yeh
Main Neutrino Interactions in Scintillator + p → ; →
ve + 12C → e 12B → 12C e ve
v + 12C → e 12N → 12C e v
v + 12C → v 12C*12C
v e v e
v p v p
KamLAND
Daya Bay
SNO+
NoVA Borexino
Excellent detection medium for neutrinos in MeV range Different LS combinations to meet the needs of various physics Profound physics applications in Solar-, Geo-, Reactor-, Supernova-Neutrinos,
Neutrino Oscillation, Proton Decay
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0ββ(e.g. SNO+, KamLAND-
Zen)
Accelerator Physics (e.g. NOA, T2K, SNS, J-
PARC-E56)
Reactor (e.g. Daya Bay, PROSPECT,
JUNO)
Solar & Geo (e.g. LENS, Borexino,
KamLAND)
Common features between detectors
unique requirement for individual detector
Liquid Scintillator (Metal-loaded & Water-based)
Other Applications
(e.g. Nonproliferation, source -, LZ)
Ion-beam therapy&
TOF-PET scan
Liquid Scintillator Physics
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Reactor
Solar
Others
Isotope-doped Liquid Scintillatorfor Neutrino Physics and Other Applications
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Liquid Scintillators
1-phenyl-1-xylyl-ethane (PXE)
1,2,4-trimethylbenzene (PC)Di-isopropylnaphthalene (DIN)
Cyclohexylbenzene (PCH)Linear alkylbenzene (LAB)
• Stability, light-yield and optical transparency• High flashpoint (PXE>DIN>LAB>PCH>PC) and low toxicity• New generation scintillation water (next)
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• A new detection medium, bridging scintillator and water, motivated by Nucleon Decay
• Tunable scintillation light from ~pure water to ~organic:
• Water-like WbLS: A scintillation water with Cherenkov and Scintillation detection
• Oil-like WbLS: A novel technology for loading various isotopes, particularly for hydrophilic elements, in scintillator
• Cherenkov transition• overlaps with scintillator energy-transfers will be
absorbed and re-emitted to give isotropic light.• emits at >400nm will propagate through the
detector (directionality).
A 50-m WbLS SK-like detector (100ph/MeV)• Tk+= 90MeV • 20% coverage with 25% QE photocathode• Deep underground >3000 m.w.e.• Fast decay at 12ns
100 photons/MeV; A.L.=20m
Water-based Liquid Scintillator
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100 1000 10000
Cha
rge
(PE
/MeV
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Beam Energy (MeV)
T1 (white Teflon) Charge (in PE/MeV)
Water SampleWbLS1 SampleWbLS2 SampleLS Sample /30
A scintillation water with fast and optical transparent light that can explore both scintillation and Cherenkov channels.
WbLS Profermance
NSRL@BNL
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Low intensity proton beams at 275, 475 (~Ethreshold), and 2000 MeV
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WbLS Optical Transmission
Continue R&D’s • reduce scattering• need large-scale measurements
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THEIAAdvanced Scintillation Detector Concept (ASDC) Workshop - May 17/18 (LBNL): 27 participants,
17 talks 50-100 kton WbLS target High coverage with ultra-fast, high efficiency
photon sensors Deep underground (e.g. 4800 mwe Homestake) Complementary program to proposed LAr
detector at LBNF (P5, Scenario-C) with comprehensive low-energy program
• Long-baseline physics (mass hierarchy, CP violation)• Neutrinoless double beta decay• Solar neutrinos (solar metallicity, luminosity)• Supernova burst neutrinos & DSNB• Geo-neutrinos• Nucleon decay• Source-based sterile searches
Scale-up from Super-K
60m
• Concept paper - arXiv:1409.5864: 50 • WATCHMAN could be the next large
water Cherenkov detector
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Onwards for a THEIA detector (e.g. Jinping) Isotope loading
• 0νββ, solar, n-tagging
Stability of Cocktail Purification
• Chemical and radioactive impurities• Large scale circulation and operation
Cherenkov/scintillation separation• WbLS cocktail tuning• Slow timing
Cherenkov light yield• Cherenkov light below 400nm being transferred
Attenuation length• Bench-top scale demonstrated; need long arm measurement or large
demonstratorBNL 1-ton
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WbLS Isotope Dopings
Lead-doped scintillator calorimeter • Solar neutrino• Total-absorption radiation detector (Medical)
Tellurium-doped scintillator detector • Double-beta decay isotope (130Te, 34% abundance)• Future ton-scale 0ββ
Lithium-doped scintillator detector • Solar neutrino (7Li, 92.5% abundance)• Reactor antineutrino (6Li, 7.6% abundance)
2. A New metal-doped technology using water-base Liquid Scintillator principal (e.g. PROSPECT, SNO+, etc.)
• Suitable for ~most metallic ions• less-selective isotope loading Require
extensive purification for radiopurity Te-LS vs. Te-WbLS
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• Solubility, light-yield, optical transmission, and radiopurity (radiogenic and cosmogenic isotopes) are the keys
1. Oragnometallic-extraction in scintillator has been successfully applied to reactor ̅ detection (e.g. Daya Bay)
• Require a mixing ligand to bring inorganic metallic ions into organic liquid scintillator
• Additional discrimination for radioactive isotopes• difficult for hydrophilic isotopes
M. Yeh
better light-yield than Nd-LS
Te-loading up to 5%
Te-WbLS (SNO+)• New water-based LS loading Te in
scintillator• Better UV (PMT region clear)• Higher light-yield• Stable for 1.5+yrs
• 0.3% Te is the baseline (phase-I); up to 5%Te stable is achieve
• Improve the optical and photon-yield at higher loading (>3%) toward a future ton-scale 0ββ experiment (phase-II)
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6Li-WbLS (PROSPECT)BNL + Yale
• New Li-doped WbLS with enhanced light-yield, optical better and PSD that has been stable over 1.5 years for PROSPECT
• Background investigations (20-L) at ORNL reactor site
• Plan to start full-scale 2-ton ND in 2015• Continue R&D for higher loading at
~0.15% (Geometry, capture time, etc.)
M. Yeh
Cherenkov/Scintillation Separation
electrons
neutrons
LSND rejects neutrons by a factor of 100 at ¼ Cherenkov & ¾ Scintillation light (NIM A388, 149, 1997).
Cherenkov is <5% of scintillation
Separation of fast Cherenkov from slowscintillation to allow directional cut• optimize scintillation light (WbLS)• slow scintillation component
Timing measurement for Particle ID (i.e. SNO+, OscSNS, etc.)
Some ongoing works at Tsinghua U.
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Tunable LY for other WbLS Physics
T2K ND-280
WATCHMAN phase-II
• 3-D medical Imaging for ion-beam therapy (5-10%WbLS) and TOF-PET (10%Pb-WbLS)
Tunable light, linear?
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NOT more the better; need optimization
Optical transparency decreases with increasing loading of isotopes
• Purification of all components to remove colored impurities
Shift the emission light to optical-cleaner region (>450nm) where is still sensible for PMT
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bis-MSB perylene
red-shift0.3%
3%
Te%
Increasing absorption
Fluor/Shifter Optimizationabs (10cm)
Wavelength (nm)
Purification Double-pass Cobalt
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Colored Impurities: colored impurity that affects the stability and optical transmission (large detector, i.e. JUNO, ASDC)
Radioisotopes: Naturally-occurred and cosmic-activated isotopes Kreduction=102-103 (SNO+)
Known for Cherenkov detector; but challenges for scintillation detector (online circulation?)
Distillation, column separation, self-scavenging, solvent washing and recrystallization are developed; need large-scale and cost-effective setup (TM to industry)
Circulation of WbLS
extensive studies by environmental researches in academia and industry
Biodegradable?• Surfactant degradation only occurs at
<50mg/L.• Surfactant at 100mg/L or higher completely
inhibits bacteria growth
1% WbLS is 105 mg/L Stable in acrylic, PP, polycarbonate Oil-like WbLS doesn’t require
circulation (e.g. Daya Bay, SNO+, PROSPECT)
Water-like WbLS might not need circulation with careful selection of vessel and materials-in-contact
• Passing 0.1 micron filter• Molecular Band Pass (EGADS)• Nanofiltration (UC Davis)• Ongoing test with bacteria test (BNL)
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Material Compatibility
10% WbLS stable in acrylic, PP, PFA, etc Atomic Force Microscopy (AFM)
acrylic in ethanol
acrylic untreated
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• A program that selects and screens the detector materials• High s/V ratio (or elevated temp) to speed up the test• Impact of material to liquid (UV, XRF, 2-m attenuation system)• Impact of liquid to material (AFM and FTIR-microscope)
• BNL has a well-quipped facility for• SNO, SNO+, Daya Bay, PROSPECT, LBNE-water, T2K
M. Yeh
ASDC Planned Demonstrators
Site Scale Target TimelineEGADS 200 ton Gd-H2O Exists
ANNIE 1 ton Gd-H2O 2018
WATCHMAN 1 kton Gd-H2O 2018
UChicago benchtop LS Exists
UCLA 1 ton LS 2015
UPenn 30L (Wb)LS Exists
SNO+ 780 ton (Wb)LS 2016
LBNL benchtop WbLS Winter2014
BNL benchtop +1-ton (M+Wb)LS 2015
WATCHMAN-II 1 kton WbLS 2019?
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Jinping?
EGADS
Gd loading andpurification
Neutron yield physics LAPPD fast timing
Water-based Liquid Scintillator
WbLS, Gd, LAPPD, HQE PMT full integration prototype
THEIATe loading
WATCHMAN
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from R&D to Physics• Each demonstrator and/or
experiment exercises different R&D topics (details with timeline in back-up)
• Parallel developments will provide inputs to a future large detector (Theia)
at Jinping?
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