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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!
2M. Yeh
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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
4M. Yeh
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
5M. Yeh
Reactor
Solar
Others
Isotope-doped Liquid Scintillatorfor Neutrino Physics and Other Applications
6M. Yeh
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)
7M. Yeh
• 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
)
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
M. Yeh
WbLS Optical Transmission
Continue R&D’s • reduce scattering• need large-scale measurements
10M. Yeh
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
11M. Yeh
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
12M. Yeh
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)
14M. Yeh
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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.
16M. Yeh
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?
17M. Yeh
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200 300 400 500 600 700 800
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
M. Yeh 18
bis-MSB perylene
red-shift0.3%
3%
Te%
Increasing absorption
Fluor/Shifter Optimizationabs (10cm)
Wavelength (nm)
Purification Double-pass Cobalt
19M. Yeh
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)
20M. Yeh
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?
22M. Yeh
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?
M.�Yeh
Back-up Slides
24M. Yeh