Water-based Liquid Scintillator and Isotope Loadings

Water-based Liquid Scintillator and Isotope Loadings

Minfang YehNeutrino and Nuclear Chemistry, Brookhaven National Laboratory

WbLS-LBNE Workshop

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Water-based Liquid Scintillator A cost-effective, new liquid medium

utilizing nonlinear light-yield as a function of scintillator % and superior optical property of water for physics below Cerenkov or low-energy neutrino detection.

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).

PID using timing cut and energy reconstruction to separate the directional Cherenkov (fast) and isotropic scintillation (slow, controllable).

Environmentally and chemically friendly. A new metal-loading technology for

different physics applications using scintillator detector.

electrons

neutrons

LSND rejects neutrons by a factor of 100 at ¼ Cherenkov & ¾ Scintillation light (NIM A388, 149, 1997).

20%LS give ~50% light as a pure LS

Minfang Yeh, BNL6/17/2014 2

LAB in cyclohexane

A WbLS Detector at LBNE

Minfang Yeh, BNL6/17/2014

200 kT water Cherenkov detector has been extensively studied for LBNE

• Interest of adding an additional 30-45kT Cherenkov detector at same location

A multi-physics WbLS detector with Cherenkov + Scintillation features for• Beam oscillation physics• Low-energy neutrinos• Proton decay

• What are the impacts of additional scintillator• If there is a Cherenkov detector• How much light is enough (Physics) and does it affect the Cherenkov

function for oscillation physics (Performance)?• Cost on top of Cherenkov

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WbLS Variety

Cerenkov (e.g. SK, SNO)

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

Oil-like• A new loading

technology for hydrophilic elements


Water-based Liquid ScintillatorWater-like• >70%H2O• Cherenkov +

Scintillation• Cost-effective

Reactor

Solar

Others

Metal-loaded LS for Neutrino Physics


Liquid Scintillator Development Facility

• A unique facility (since 2002) for Radiochemical, Cerenkov, and Scintillator (water‐based and metal‐doped) detectors for particle physics experiments.

• Expertise trained and facility established over years of operations.• $1M facility including XRF, LC‐MS, GC‐MS, TFVD, FTIR, UV, Fluorescence

emission, light‐yield coinc. PMT, 2‐m system, low bkg. counting, etc. (access to ICP‐MS at SBU) for detector R&Ds and prototype tests.


WbLS Cherenkov & Scintillation Detection

K+ μ+ e+

μ+

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p → K+ + ν e+ + νμ + νe _μ+ + νμ

12 ns 2.2 μs

• Proton decay remains to be one of the top challenges• A simulated event with 90 scintillation photons/MeV in a SK detector forp → k v• An order of magnitude improvement over the current SK sensitivity (2.31033 yrs)

Minfang Yeh, BNL 76/17/2014

SNO+ (0ββ)

T2K (Near detctor)

PROSPECT (US‐SBL)

Others (under discussion)

Common features between detectors

unique requirement for individual detector

Liquid Scintillator(Metal‐loaded & Water‐based)

WATCHMAN (nonproliferation, p‐decay, etc.)

Ion‐beam therapy&

TOF‐PET scan

WbLS Applications


Detector Requirements

Experiment Detector ComponentsSNO+ WbLS (90%+) doped with 3%Te (130) 0ββ isotope

PROSPECT WbLS (70%+) doped with 0.1% Gd or 6Li with high PSD

WATCHMAN WbLS (1%) doped with 0.1%Gd

T2K WbLS (10%)

Medical Applications

WbLS (1-5%) for QA phantom or doped with high Z element (~10%) for TOF-PET


• Oil-like WbLS (>70% LS): SNO+, PROSPECT• Water-like WbLS (>70% H2O): T2K, medical imaging, WATCHMAN• Various surfactants for different liquid mediums

Good Attenuation Length

Fast Timing

• Started R&D since 2009• A clean liquid (at 450nm and above);

need 104 optical purification • A fast pulse• can load as much as 35% of LS in

H2O• Investigate light propagation

below and above Cerenkov• proton beams & sources

1% WbLS-2012


WbLS Detectors

NSRL @BNL

210 MeV dE/dx ~ K+ from PDK

475 MeV Cerenkov threshold

2 GeV MIP

3 low Intensity Proton BeamsWater pure water

WbLS 1 0.4% LS

WbLS 2 0.99% LS

LS pure LS

4 Material Samples

Tub 1PTFE

(highly reflective white Teflon)

Tub 2 Aluminum coated with black Teflon

2 Detectors

Proton-beam Measurements at BNL


• Two NSRL runs from 2012-2013• Same sample; different geometries• Cherenkov at higher energy and scintillation

below Č threshold• David’s talk next

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A New Game of Metal-doped Scintillator


Lead-doped scintillator calorimeter • Solar neutrino (large ratio of absorption length to radiation length

to differentiate e CC events from NC as electron-hadron separation)

• Total-absorption radiation detector

Lithium-doped scintillator detector • Solar neutrino (7Li, 92.5% abundance)• Reactor antineutrino (6Li, 7.6% abundance)

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Conventional loading is no good for hydrophilic ions (i.e. Te)

• Conventional loading method using organic complexing ligands has been successfully applied to reactor ̅ detection (Gd-LS)

• –OH group is a known quencher• difficult for hydrophilic elements

• WbLS adds a new dimension of metal-loading

8-MeV ’s (Gd) vs. ,T (6Li)

Neutron Tagging

Tellurium-doped scintillator detector • Double-beta decay isotope (130Te, 34% abundance)• Future ton-scale 0ββ

Te-WbLS to SNO+


• 0.3% Te is the baseline (phase-I)• Higher loading (3%) and background controls (purification) of Te-

LS are the keys to a future ton-scale 0ββ experiment (phase-II)better light-yield and optical than Nd-LS

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0.3%Nd-LAB-PPO0.3%Te-LAB-PPOPPO emission at 313nmPMT QE

Double-pass Co

Te-loading

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Li-WbLS to PROSPECT

Minfang Yeh, BNL

Daya Bay PROSPECT

BNL + Yale

PSD enhancement for 0.1% Gd-doped LS (compatible with plastics) over 6 months; and further improvement can be achieved

6/17/2014

A stable 0.1% Li-LS at ~5000 ph/MeV

• A Li-doped LS that has been stable over 1.5 years (light-yield and optical better than commercial product)

• Improve PSD of a new Gd-doped LS • Large cells filled with this Gd-LS ready for prototype

test • Plastics scintillator is another possibility• Background investigations at three different reactor

sites• Start full-scale (~10 tons) at Near Site in 2015

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0.1% Li - 2nd formulation0.1% Li Commercial ProductLAB + PPO + MSB

WbLS to T2K-ND280 An active H2O target from WbLS will

allow:• Improving reconstruction within the

scintillator tracking detectors• vertexing in the water volume, enhancing the

need for subtraction, also will help with rejection of external backgrounds

Heavy water-based liquid scintillator to isolate the scattering of neutron bound in D by D2O-H2O subtraction analysis?


• PD: large scintillator tracking detector with water bags that can be filled/empty

• FGD: two detectors, one fully active scintillator (~CH) and one alternating active scintillator and passive H2O modules

• Same H2O target at Near/Far detectors• A demonstrator for LBNE or HK? 1

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WbLS-10%pure LSWbLS-1%

WbLS for Medical Physics proton beam therapy enables more precise,

delivered radiation dose; especially important for tumors in close proximity to vital healthy organs.

better match to tissue properties providing a medium more familiar to dosimetrists and medical physicists, who plan treatments in terms of water-equivalent depth.

Better combustibility and chemical hazard issues with conventional liquid scintillator.

a much longer attenuation length, and therefore presumably significantly less resolution deterioration from light scattering in the medium.

less confusion from background Cerenkov light (the proton beam energy itself is well below the Cerenkov threshold, but knock-on electrons can produce some Cerenkov radiation).

The WbLS volume would be viewed (see Fig. 1) by CCD cameras from three orthogonal sides to provide three simultaneous two-dimensional projections of the light generated by the energy deposition of the proton beam stopping in the scintillator.

• SBIR• very strong science and technology

review in 2013 (luck of IP agreement and patent protection)

• will resubmit in 2014• BNL OTCP proposal approved


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WbLS-2014 (extinction coefficient)WbLS-2012SK-water

1% WbLS-2014


• Water-like WbLS (e.g. WATCHMAN or LBNE)

• The WbLS-2012 needs 104 optical purification

• relying on the vendor for a cleaner starting material

• Multi-step technologies proven; but high cost and labor-consuming

• The WbLS-2014 • New chemical components• Non-purified and includes scattering; need

to measure its effect• extinction coefficients calculated from each

component (successfully predict LS)• total = organic + water• organic ~ water ~ 0.0046 (m-1) at 430nm• Region of 300-400nm dominated by

flour/shifter; need to be optimized

optical improvement after one-pass

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WbLS non-purified

1% WbLS-2014 cont’d


WbLS light-yield as a function of LS% loading

• Higher light-yield at the cost of optical transmission

Linear correlation between light-yield and LS% (up to ~15%)

• Different behavior with that of pure scintillator

WbLS-2014 has ~25% more light-yield than WbLS-2012

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WbLS 2014WbLS 2012

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WbLS 1%

WbLS 4.7%

WbLS 8.14%

WbLS 10.1%

WbLS 13.9%

LS

H2O

WbLS 1% (NSRL 2012)

Material Cost

WbLS (at 1 kiloton or higher)• Organic Solvent ($100 for every %LS in a ton)• H2O (excluded)• Fluor/Shifter: $600/ton (PPO at 2g/L for pure LS detector)

- For 1% WbLS, 0.02gL for $6/ton?- Other shifters?- optimization to save cost

• A water-like 1% WbLS: $0.1k + $fluor per ton• An oil-like WbLS (e.g. SNO+ or PROSPECT), cost is

dominated by price of oil• Converting from an existing water Cherenkov detector

- a cost-effective option- 1 kT WATCHMAN at IMB (Gd-water, Phase-I); what a 35kT

WATCHMAN at LBNE looks like?- converting WATCHMAN to Gd-WbLS (Phase-II)


Equipment Cost Purification System

• Organic (applied before mixing with H2O)- Thin-film Vacuum Distillation (~$120k) - High-Pressure Exchange Column ($60k)- Filtration ($40k)

• H2O (before and after mixing with organics)- Circulation constantly during the operation for a typical

Cherenkov detector- Leaching- Micro-organism

- What happens after mixing with organics? Circulation?- Water System (LBNE, SNO or T2K; est. $350k?)

Blending System• Depending on production scale• ~$120k (4-ton batch)


Circulation of WbLS


extensive studies by environmental researches in academia and industry

Biodegradable?• Surfactant degradation (e.g. LAS) only

occurs at <50mg/L.• Surfactant at 100mg/L or higher completely

inhibits bacteria growth

1% WbLS is 105 mg/L Stability and Compatibility (acrylic)

tests have been ongoing for 2+ years for WbLS-2012 and 6 months for WbLS-2014

Water-like WbLS might not need circulation if careful selection of vessel and material-in-contact

• Passing 0.1 micron filter is ok

Oil-like WbLS doesn’t require circulation (e.g. SNO+, PROSPECT)

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Summary

Principals of WbLS detection and isotope loading are proven; the current developments focus on ongoing and newly proposed experiments (every detector has different requirements); 1-ton prototype is under construction

Optimization on Reachable Technology and Cost Reduction; A new WbLS-2014

With the additional low-energy and other Physics, what are the impacts to LBNE beam oscillation physics (compared to a Cherenkov detector)?

A new (WbLS detector) opportunity for LBNE with profound physics; plus LAPPD?


Water-based Liquid Scintillator and Isotope Loadings

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