Metal-doped and Water- based Liquid Scintillator for Neutrino Research

Minfang Yeh Neutrino and Nuclear Chemistry

LSC2017, Copenhagen, 05/01-05/2017

What is Neutrino?

• Ghost particle postulated by Pauli in 1930

• An electrically neutral, weakly interacting

elementary subatomic particle with half- integer spin

• A detector uses large (from hundreds to thousands of tonnes)

detection medium, such as water, scintillator, or noble gas,

operated over many years to accumulate statistics

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Sources of Neutrinos

Neutrino probes back to the beginning of universe (asymmetry) and into the solar and supernova system (along with other applications)

Formaggio, J.A. et al. Rev.Mod.Phys. 84 (2012) 1307-1341

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Sources of Neutrinos

Neutrino probes back to the beginning of universe (asymmetry) and into the solar and supernova system (along with other applications)

Formaggio, J.A. et al. Rev.Mod.Phys. 84 (2012) 1307-1341

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Leon M. Lederman Jack Steinberger Melvin Schwartz

1988: for the neutrino beam method and the demonstration of the doublet structure of the

leptons through the discovery of the muon neutrino

2002: for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos

1995 (share): for the detection of the neutrino and "for pioneering experimental contributions to lepton physics

Raymond Davis Jr. Masatoshi Koshiba

Takaaki Kajita Arthur B. McDonald

2015: for the discovery of neutrino oscillation, which shows that neutrinos have mass

Frederick Reines

Neutrino in Nobel Prize from Discovery to Precision…

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Neutrino Flavors and

Oscillations

Solar (SNO)

Atmospheric (Super-K)

Reactor (KamLAND)

Accelerator (T2K)

Solar (Homestake)

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Change of Neutrino flavors via Oscillations as a function of distance,

energy, and mixing angle

Neutrino Flavors and

Oscillations

Solar (SNO)

Atmospheric (Super-K)

Reactor (KamLAND)

Accelerator (T2K)

Neutrinos are not massless and Evidence of flavor conversion

Solar (Homestake)

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KamLAND

Daya Bay

SNO+

NoVA Borexino

Scintillator is an excellent detection medium for neutrinos in MeV range

Tune scintillator cocktails to meet the needs of various physics

Neutrino Interactions in

Liquid Scintillator

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z solvent WLS

fast and slow components

Scintillation Mechanism

• Stokes shift, timing structure, and C/H density determine the neutrino detector responses

wiki

Stokes shift

fast

slow

Ranucci et al.

Birk’s

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LAB-based

DIN-based

n

n

• PSD to distinguish different particle interactions; i.e. proton recoils from electron-like events

• Select IBD events from cosmogenic fast neutrons and ambient-related gammas;

• Essential for Near-surface Detector • Different scintillators loaded with different metallic

ions for different detector operations

Scintillator key feature Pulse Shape Discrimination

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electrons

neutrons

LSND rejects neutrons by a

factor of 100 at ¼ Cherenkov & ¾ Scintillation light (NIM A388, 149, 1997).

Cerenkov is <5% of scintillation

Separation of Cherenkov from scintillation allows directional cut for particle ID to select/reject events

• Ratio of scintillation light in Cherenkov

• Slow scintillation decay time

• Adequate scintillation yield

Key R&D for future scintillator detectors

Prompt Cherenkov peak

Long scintillation tail

Scintillator key feature Cherenkov/Scintillation Separation

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Scintillator Components

C. Buck and M. Yeh, J. Phys. G: Nucl. Part. Phys. 43 093001 (2016)

Scintillator cocktails of high photon yield, long-term stability, long attenuation length, low toxicity, and high flash point are required

for neutrino detector

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SNO

SNO

A 12-m (dia.) acrylic

vessel containing ~1,000,000 liters of liquid, situated ~2km

underground at Sudbury Mine

Liquid Scintillators

1-phenyl-1-xylyl-ethane (PXE)

1,2,4-trimethylbenzene (PC)

Di-isopropylnaphthalene (DIN)

Cyclohexylbenzene (PCH)

Linear alkylbenzene (LAB)

C. Buck and M. Yeh, J. Phys. G: Nucl. Part. Phys. 43 093001 (2016)

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Primary and Secondary

Wave-Length-Shifter C. Buck and M. Yeh, J. Phys. G: Nucl. Part. Phys. 43 093001 (2016)

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Examples of (some) Scintillator Cocktails

Daya Bay (0.1 wt.%) Gd-LS produced in Oct. 2010 (monitored at BNL); property no change over

5 years (Stability) Oct 2015

C. Buck and M. Yeh, J. Phys. G: Nucl. Part. Phys. 43 093001 (2016)

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Cerenkov (e.g. Super-K, SNO)

Scintillator (e.g. SNO+, Daya Bay)

Cherenkov vs Scintillation

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water-like WbLS Oil-like WbLS • Cherenkov and

Scintillation detection

• Metal-loaded LS

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Cherenkov (e.g. Super-K, SNO)

Water-based Liquid Scintillator

Scintillator (e.g. SNO+, Daya Bay)

If you always do what you always did, you will always get what you always got. -Albert Einstein

H2O 1%WbLS 10%WbLS LS

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A 50-m WbLS SK-like detector (100ph/MeV) •

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T k+ = 90MeV 20% coverage with 25% QE photocathode

Deep underground >3000 m.w.e. Fast decay at 12ns

WbLS to know • A new detection medium, bridging

scintillator and water Tunable scintillation light from ~pure water to ~organic; capable of Cherenkov and scintillation

•

detection and loading of

hydrophilic element • Environmental friendly with high

f.p. for UG physics

• 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).

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WbLS Properties

1%WbLS ~109 op/MeV

L.J. Bignell et al 2015 JINST 10 P12009

NSRL

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WbLS Properties

1%WbLS ~109 op/MeV

L.J. Bignell et al 2015 JINST 10 P12009

NSRL

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See scintillation below Cherenkov

threshold

Metal-doped (Wb)LS for Neutrino Physics and Other Applications

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Reactor

Metal-doped (Wb)LS for Neutrino Physics and Other Applications

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Early Development of M-

doped LS • LENS plays a key role

Indium loaded scintillator for low energy solar neutrino spectroscopy, L. N. Pfeiffer, A. P. Mills, R. S.

Raghavan and E. Chandross, Phys. Rev. Lett. 41, 63 (1978).

C. Buck and M. Yeh, J. Phys. G: Nucl. Part. Phys. 43 093001 (2016)

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(Selected) LS Exptʼs current operation or under construction

Accelerator neutrino (Gd-LS) Short-baseline reactor neutrino 6 Li-LS

Neutrinoless double beta decay (Te-doped LS)

Dark matter search (Gd-LS) Long-baseline reactor neutrino (pure LS)

Reactor neutrino (i.e. Daya Bay); Gd-LS

…there are more (sorry)…

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A complementary; not competitive scintillation water detector for DUNE

WATCHMAN-II

(DNN)

“the U.S. to host a large water Cherenkov neutrino detector, as

one of three additional high- priority activities, to complement the DUNE liquid argon detector…This approach would be an excellent example of

global cooperation and planning” – P5 (Scenario C)

A future (scintillation) water detector (THEIA)

THEIA

60m

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~20kT WbLS

http://newatlas.com/relics-physics- archaeology-roman-lead/30032/#p246488

(Image: University of Bern)

• Highly motivated by its scientific merits with strong international interests; A ton-

scale NLDBD experiment is recommended with 5-year R&D plan (US)

• Scintillator (SNO+ like) is a low-cost option with capability of deploying in large

mass loaded with high% (>ton) of double-beta decay isotope

Ton-scale 0 experiments (future)

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1. 3-D Imaging TOF-PET •

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Radiation calorimetry 10% Gd- or Pb-doped WbLS University collaborator: U. Chicago PCT Patent submission in 2016

2. WbLS-based “phantom” as a real- time quality assurance device • Intensity-modulated pencil proton

beam therapy (IMPT) in which a tumor can be targeted for radiation while sparing the surrounding healthy tissue

F. Reines

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Medical Application

What can we learn from LS experts?

the best way to predict your future is to create it – Abraham Lincoln

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UC Davis at BNL

UM/CSU/UF/KEK at BNL

• LBNL/UC Berkeley/UC Chicago: Developing facility for WbLS timing and light yield in a cosmic-muon imaging experiment using fast PMTs

• UC Irvine/LLNL: 100-L production for long-arm attenuation measurement

• UC Davis: 10L production for in situ (nanofiltration) circulation study: purification by differentiating molecular sizes (with BNL)

• CSU/TRIUMF: T2K-ND High light yield WbLS with 70% water target

• LBNL/UCB/UCD/LLNL: RAT-PAC software framework for simulation (GEANT4) & reconstruction

• Yale/NIST/LLNL: Li-doped LS

• UM/CSU/BCC: PSD-enhanced Gd-doped LS

• All: New liquid scintillator/fluor/WLS?

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New Liquid Scintillator?

Better and Larger Purification Technique? Nitrogen purging

• Radon removal

• Oxygen quenching

Distillation

• Radioisotope removal

• Colored impurities

Water extraction

• radioisotope removal (e.g. Recrystallization

K in PPO)

Sublimation

• M-BDK, PPO, etc.

Column purification

• Colored organic removal

• Metal removal

Nanofiltration

• U/Th removal from metal-

feedstock (e.g. Gd-H2O)

• WbLS?

• PPO, metal-feedstock (e.g. TeOH 6 )

Major techniques developed by Borexino, KamLAND, SNO+, and JUNO

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Co removal from LS

ONP-supported

• Neutrino research marching to precision era; focusing on CP-violation and Majorana phase Liquid scintillator remains as a main detector medium for neutrino detection Water-based liquid scintillator has continuing to gain the interests from international science communities We would welcome your participation!

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Scintillator Applications (from neutrino view)

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Summary

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Brookhaven National Lab

Neutrino and Nuclear Chemistry Group (PI: Yeh) Neutrino is at exciting stage of precision

measurement • long-range plan for next generation experiments

• BNL is a key institute for several ongoing and future neutrino experiments

A synergetic activity between physics and chemistry divisions

Available resources, from benchtop to ton-scale prototype, are given in next few slides

Contact yeh@bnl.gov for postdoc/RA position

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• An existing facility for water-based and metal-doped liquid scintillator Detector R&D for particle physics applications.

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Operating since 2009: DayaBay, SNO+, LZ, PROSPECT, T2K-ND, JSNS Instrumentation including XRF, LC‐MS, GC‐MS, TFVD, FTIR, UV, Fluorescence emission, light‐yield coincident PMT, 2‐m system, low bkg. Counting…etc. (access to ICP‐MS at SBU and other facilities) A ton-scale liquid production facility is under construction (only at US Res. Inst.)

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Liquid Scintillator Development Facility

Simulated cosmic muon in water. Red points are absorbed & reflected photons

No black barrier

With black barrier

Study Cerenkov separation as a function of

LS% in WbLS

Strong university participations (welcome)

1000L (Wb)LS prototype

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A unique ton per batch liquid scintillator production facility at BNL

Prioritized Mission for LZ 17.5-ton radiopure 0.1%Gd-LS (veto) in FY18

Liquid storage warehouse

Scheme for ton-scale production from

purification to synthesis

Storage capacity of tens of tons of scintillator; available for other scintillator applications in FY19

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Ton-scale Scintillator Production Facility