Water-based Liquid Scintillator and Isotope Loadings Minfang Yeh - - PowerPoint PPT Presentation

Water-based Liquid Scintillator and Isotope Loadings

Minfang Yeh

Neutrino and Nuclear Chemistry, Brookhaven National Laboratory

WbLS-LBNE Workshop

2000 4000 6000 8000 10000 12000 50 100

Optical Photons per MeV LS%

Water-based Liquid Scintillator

• A cost-effective, new liquid medium

utilizing nonlinear light-yield as a function

• f 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, BNL 6/17/2014 2 LAB in cyclohexane

A WbLS Detector at LBNE

Minfang Yeh, BNL 6/17/2014

• 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

3

4

20 40 60 80 100 120 140 160 180 100 1000 10000 Mean Absorption Length (m) Photon/MeV

WbLS Variety

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

Oil-like

• A new loading

technology for hydrophilic elements

Minfang Yeh, BNL 6/17/2014

Water-based Liquid Scintillator

Water-like

• >70%H2O
• Cherenkov +

Scintillation

• Cost-effective

Reactor  Solar Others

Metal-loaded LS for Neutrino Physics

Minfang Yeh, BNL 6/17/2014 5

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.

Minfang Yeh, BNL 6/17/2014 6

WbLS Cherenkov & Scintillation Detection

K+ μ+ e+ μ+ e+

Hit Time (Time of Flight Corrected) [ns] Number of PE

10 102 103 104 50 10 15

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 for p → kv
• An order of magnitude improvement over the current SK sensitivity (2.31033 yrs)

Minfang Yeh, BNL 7 6/17/2014

SNO+ (0ββ) 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

Minfang Yeh, BNL 6/17/2014 8

Detector Requirements

Experiment Detector Components

SNO+

WbLS (90%+) doped with 3%Te (130) 0ββ 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

Minfang Yeh, BNL 6/17/2014 9

• 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

Minfang Yeh, BNL 6/17/2014 10

WbLS Detectors

NSRL @BNL

210 MeV dE/dx ~ K+ from PDK 475 MeV Cerenkov threshold 2 GeV MIP

3 low Intensity Proton Beams

Water pure water WbLS 1 0.4% LS WbLS 2 0.99% LS LS pure LS

4 Material Samples

Tub 1 PTFE (highly reflective white Teflon) Tub 2 Aluminum coated with black Teflon

2 Detectors

Proton-beam Measurements at BNL

Minfang Yeh, BNL 6/17/2014

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

below Č threshold

• David’s talk next

11

A New Game of Metal-doped Scintillator

Minfang Yeh, BNL 6/17/2014

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)

12 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 0ββ

Te-WbLS to SNO+

Minfang Yeh, BNL 6/17/2014 13

• 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 0ββ experiment (phase-II)

better light-yield and optical than Nd-LS

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.005 0.01 0.015 0.02 300 400 500 600 PMT (QE) Absorbance Wavelength (nm)

0.3%Nd-LAB-PPO 0.3%Te-LAB-PPO PPO emission at 313nm PMT QE

Double-pass Co Te-loading

14

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

0.01 0.02 0.03 0.04 0.05 200 700 Absorbance Wavelength (nm)

51213 71913 90813 103113

500 1000 1500 2000 2500 3000 3500 4000 1000 Counts (AU) ADC Channel

0.1% Li - 2nd formulation 0.1% Li Commercial Product LAB + 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?

Minfang Yeh, BNL 6/17/2014 15

• PD: 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 10 100 1000 10000 100000 1 100 Counts Channel

WbLS-10% pure LS WbLS-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

Minfang Yeh, BNL 6/17/2014 16

0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 200 300 400 500 600 Absorption Length (1/m) Wavelength (nm)

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

1% WbLS-2014

Minfang Yeh, BNL 6/17/2014

• Water-like WbLS (e.g. WATCHMAN
• r 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

• ptical improvement after one-pass

17

WbLS non-purified

1% WbLS-2014 cont’d

Minfang Yeh, BNL 6/17/2014

• 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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1 10 100 1000 0.1 1 10 100

Compton Edge, AU

LS % in Water

WbLS 2014 WbLS 2012

1 10 100 1000 10000 1 10 100 1000 Counts (AU) ADC Channels

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?
• ptimization 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)

Minfang Yeh, BNL 6/17/2014 19

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)

Minfang Yeh, BNL 6/17/2014 20

Circulation of WbLS

Minfang Yeh, BNL 6/17/2014

extensive studies by environmental researches in academia and industry

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

21

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?

Minfang Yeh, BNL 6/17/2014 22