Water-based Liquid Scintillator and Isotope Loadings Minfang Yeh Neutrino and Nuclear Chemistry, Brookhaven National Laboratory WbLS-LBNE Workshop
Water-based Liquid Scintillator 12000 A cost-effective, new liquid medium Optical Photons per MeV LAB in cyclohexane 10000 utilizing nonlinear light-yield as a function of scintillator % and superior optical 8000 property of water for physics below 6000 Cerenkov or low-energy neutrino 4000 detection. 2000 Cherenkov transition 20%LS give ~50% light as a pure LS 0 overlaps with scintillator energy-transfers will be • 0 50 100 absorbed and re-emitted to give isotropic light. emits at >400nm will propagate through the • LS% detector (directionality). PID using timing cut and energy electrons reconstruction to separate the directional LSND rejects neutrons by a Cherenkov (fast) and isotropic scintillation factor of 100 at ¼ Cherenkov (slow, controllable). & ¾ Scintillation light (NIM A388, 149, 1997). Environmentally and chemically friendly. A new metal-loading technology for different physics applications using neutrons scintillator detector. 6/17/2014 Minfang Yeh, BNL 2
A WbLS Detector at LBNE 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 • 6/17/2014 Minfang Yeh, BNL 3
WbLS Variety 180 160 Mean Absorption Length (m) 140 Cerenkov (e.g. SK, SNO) 120 100 Water-based Liquid Scintillator 80 Water-like Oil-like • >70%H2O • A new loading 60 • Cherenkov + technology for Scintillation hydrophilic 40 • Cost-effective elements 20 Scintillator (e.g. SNO+, Daya Bay) 0 100 1000 10000 Photon/MeV Minfang Yeh, BNL 6/17/2014 4
Metal-loaded LS for Neutrino Physics Reactor Solar Others 6/17/2014 Minfang Yeh, BNL 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. 6/17/2014 Minfang Yeh, BNL 6
WbLS Cherenkov & Scintillation Detection • Proton decay remains to be one of the top challenges A simulated event with 90 scintillation photons/MeV in a SK detector for p → k � v � • An order of magnitude improvement over the current SK sensitivity (2.3 10 33 yrs) • μ + 15 Number of PE 0 p → K + + ν μ + + ν μ _ e + + ν μ + ν e 10 12 ns 0 2.2 μ s μ + e + e + 50 K + 10 10 2 10 3 10 4 Hit Time (Time of Flight Corrected) [ns] 6/17/2014 Minfang Yeh, BNL 7
WbLS Applications SNO+ (0 ββ ) PROSPECT (US ‐ SBL) Common features between detectors Ion ‐ beam therapy WATCHMAN Liquid Scintillator & (nonproliferation, ( Metal ‐ loaded & Water ‐ based) TOF ‐ PET scan p ‐ decay, etc.) unique requirement for individual detector Others T2K (Near detctor) (under discussion) 6/17/2014 Minfang Yeh, BNL 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 6 Li with high PSD WATCHMAN WbLS (1%) doped with 0.1%Gd T2K WbLS (10%) Medical WbLS (1-5%) for QA phantom or doped with high Z Applications element (~10%) for TOF-PET • Oil-like WbLS (>70% LS): SNO+, PROSPECT • Water-like WbLS (>70% H 2 O): T2K, medical imaging, WATCHMAN • Various surfactants for different liquid mediums 6/17/2014 Minfang Yeh, BNL 9
1% WbLS-2012 • Started R&D since 2009 • A clean liquid (at 450nm and above); Good Attenuation Length need 10 4 optical purification • A fast pulse • can load as much as 35% of LS in H 2 O • Investigate light propagation below and above Cerenkov • proton beams & sources Fast Timing 6/17/2014 Minfang Yeh, BNL 10
Proton-beam Measurements at BNL WbLS Detectors • Two NSRL runs from 2012-2013 • Same sample; different geometries • Cherenkov at higher energy and scintillation NSRL @BNL below Č threshold • David’s talk next 2 Detectors 3 low Intensity Proton Beams 4 Material Samples PTFE Water pure water 210 MeV dE/dx ~ K+ from PDK Tub 1 (highly reflective WbLS 1 0.4% LS white Teflon) 475 MeV Cerenkov threshold WbLS 2 0.99% LS Aluminum coated Tub 2 with black Teflon 2 GeV MIP LS pure LS 6/17/2014 Minfang Yeh, BNL 11
A New Game of Metal-doped Scintillator • Conventional loading method using organic Conventional loading is no good for hydrophilic ions (i.e. Te) 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 Lithium-doped scintillator detector Neutron Tagging • Solar neutrino ( 7 Li, 92.5% abundance) • Reactor antineutrino ( 6 Li, 7.6% abundance) Tellurium-doped scintillator detector • Double-beta decay isotope ( 130 Te, 34% abundance) Future ton-scale 0 ββ • 8-MeV ’s (Gd) vs. ,T ( 6 Li) 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 6/17/2014 Minfang Yeh, BNL 12
Te-WbLS to SNO+ 0.02 0.14 0.3%Nd-LAB-PPO 0.12 0.3%Te-LAB-PPO 0.015 PPO emission at 313nm 0.1 PMT (QE) Absorbance PMT QE 0.08 0.01 0.06 0.04 0.005 0.02 0 0 300 400 500 600 Wavelength (nm) Double-pass Co Te-loading • 0.3% Te is the baseline (phase-I) • Higher loading (3%) and background controls (purification) of Te- better light-yield and optical than Nd-LS LS are the keys to a future ton-scale 0 ββ experiment (phase-II) 6/17/2014 Minfang Yeh, BNL 13
Li-WbLS to PROSPECT 4000 0.1% Li - 2nd formulation 3500 0.1% Li Commercial Product • A Li-doped LS that has been stable over 1.5 years 3000 Counts (AU) LAB + PPO + MSB BNL + Yale (light-yield and optical better than commercial 2500 product) 2000 • Improve PSD of a new Gd-doped LS 1500 • Large cells filled with this Gd-LS ready for prototype 1000 test 500 • Plastics scintillator is another possibility 0 • Background investigations at three different reactor 0 1000 ADC Channel sites A stable 0.1% Li-LS at ~5000 ph/MeV • Start full-scale (~10 tons) at Near Site in 2015 0.05 51213 71913 0.04 90813 103113 0.03 Absorbance 0.02 0.01 PROSPECT Daya Bay 0 200 700 PSD enhancement for 0.1% Gd-doped LS (compatible with plastics) over 6 months; and further improvement can be achieved Wavelength (nm) 6/17/2014 Minfang Yeh, BNL 14
WbLS to T2K-ND280 An active H 2 O 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 D 2 O-H 2 O subtraction analysis? 100000 WbLS-10% pure LS P D: large scintillator tracking detector • WbLS-1% 10000 with water bags that can be filled/empty FGD: two detectors, one fully active • 1000 Counts scintillator (~CH) and one alternating active scintillator and passive H 2 O 100 modules 10 Same H 2 O target at Near/Far detectors • A demonstrator for LBNE or HK? • 1 1 100 Channel 6/17/2014 Minfang Yeh, BNL 15
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. The WbLS volume would be viewed (see Fig. 1) by CCD cameras from three orthogonal sides to provide three a much longer attenuation length, and simultaneous two-dimensional projections of the light therefore presumably significantly less generated by the energy deposition of the proton beam resolution deterioration from light scattering stopping in the scintillator. in the medium. • SBIR less confusion from background Cerenkov • very strong science and technology light (the proton beam energy itself is well review in 2013 (luck of IP agreement below the Cerenkov threshold, but knock-on and patent protection) electrons can produce some Cerenkov • will resubmit in 2014 • BNL OTCP proposal approved radiation). 6/17/2014 Minfang Yeh, BNL 16
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