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

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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

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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.)

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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

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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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Back-up Slides

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