Water-based Liquid Scintillator

Transcription

1 Water-based Liquid Scintillator Minfang Yeh Neutrino and Nuclear Chemistry, Brookhaven National Laboratory NNN-2014, Nov. 4-6, 2014

2 Liquid Scintillator Physics 0 ββ (e.g. SNO+, KamLAND-Zen) Reactor (e.g. Daya Bay, PROSPECT, JUNO) Other Applications (e.g. Nonproliferation, source -, DM) Common features between detectors Liquid Scintillator (Metal-loaded & Water-based) unique requirement for individual detector Ion-beam therapy & TOF-PET scan Solar & Geo (e.g. LENS, Borexino, KamLAND) Accelerator Physics (e.g. NO A, T2K) 2

3 BNL-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. 3

4 Cherenkov vs. Scintillator Det. Extinction Length (m) Cherenkov (e.g. SK, SNO) Water-based Liquid Scintillator in a range of scin. light at different att. lengths Scintillator (e.g. SNO+, Daya Bay) Photon/MeV 4

5 Water-based Liquid Scintillator Tunable scintillation light (LAB, PC, DIN, PXE, PCH, EJ309,, etc.) from ~pure water to ~organic: Water-like WbLS: A cost-effective scintillation water with Cherenkov and Scintillation detection Oil-like WbLS: A new isotope loading scintillator technology, particularly for hydrophilic elements Anionic Cationic Nonionic Amphoteric ethylene-oxide, sulfonic acid, amine, alkyl sulfate, octylphenyl-ether,, etc. 5

6 Isotope-doped Liquid Scintillator for Neutrino Physics and Other Applications Reactor Solar Others Some are easier than others! 6

7 Oil-like WbLS (Isotope Loading) Conventional loading is no good for hydrophilic ions (i.e. Te) Conventional method has been successfully applied to reactor detection (e.g. Gd-LS) Mixing ligands are mostly quencher difficult for hydrophilic isotopes WbLS is a Novel Technology of doping isotopes in scintillator Lithium-doped scintillator detector Solar neutrino ( 7 Li, 92.5% abundance) Reactor antineutrino ( 6 Li, 7.6% abundance) Neutron Tagging Tellurium-doped scintillator detector Double-beta decay isotope ( 130 Te, 34% abundance) Future ton-scale 0 ββ Lead-doped scintillator calorimeter Solar neutrino Total-absorption radiation detector 8-MeV s (Gd) vs.,t ( 6 Li) 7

8 Solar Neutrino Targets 115 In + e 115 Sn + e - + (τ =4.76 μs) 2 γ (LENS) High nature abundance at 95.7% Low Q value at 114-keV, sensitive to >95% pp continuum Triple coincidence allows tagging of e event 6-8% loading with conventional organometallic technology 208 Pb + e 208 Bi* + e - & 208 Pb + x 208 Pb* + x (HALO) Abundance at 52.4% Bursts of neutrons via CC and NC Neutron detection by IBD reaction using scintillator ( 208 Pb is a double magic nuclei) Targeting 10% nat Pb using WbLS (aligned with medical applications) 7 Li + e 7 Be + e - group state (E thresh = MeV) and first excited state (E thresh = MeV) High abundance at 92.5% Conventional organometallic loading is not stable (e.g. Bugey-3) 1~3% loading using WbLS (aligned with short-baseline reactor experiments) Few others: 11 B, 35 Cl, 31 P,, etc. 8

9 6 Li-WbLS (PROSPECT) A Li-doped ( %) LS that has been stable over BNL + Yale 1.5 years (light-yield and optical better than commercial product) for PROSPECT Background investigations at three different reactor sites Start full-scale (~10 tons) at Near Site in D-PSD to distinguish IBD events from Cosmogenic fast neutrons Reactor-related gammas Continue R&D for higher loading at >0.2% Counts (AU) % Li - 2nd formulation 0.1% Li Commercial Product LAB + PPO + MSB ADC Absorbance Wavelength (nm) M.YehNNN2014 9

10 Te-WbLS (SNO+) Absorbance %Nd-LAB-PPO 0.3%Te-LAB-PPO PPO emission at 313nm PMT QE Wavelength (nm) PMT (QE) Double-pass Co Te-loading better light-yield and optical than Nd-LS 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) 10

11 -shifting for higher % M-doped WbLS %_PRS_0.3%_Te 20%_PRS_1.2%_Te 20%_PRS_2%_Te 2.0% 25%_PRS_3%_Te 3.0% %Te-LS at SNO+ corresponding to ~2 tons of 130 Te at R<3.5m Optical transparency and light-yield decrease with increasing loading of isotopes Bis-MSB perylene Red-shift the light Fish tank test at U Penn Scintillation-optimized PMT (~450nm)? High QE PMT 11

12 Water-Like WbLS A new liquid medium utilizing nonlinear light-yield as a function of scintillator % and superior optical property of water for physics below Cerenkov (e.g. nucleon decay) 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) Cost-effective and environmentally friendly for a large scintillation Cherenkov detector Cherenkov is ~5% of scintillation electrons LSND rejects neutrons by a factor of 100 at ¼ Cherenkov & ¾ Scintillation light (NIM A388, 149, 1997). neutrons 12

13 WbLS for Proton Decay 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 ( yrs) μ + Number of PE p K + + ν μ + + _ νμ e + + νμ + νe 12 ns 2.2 μs K + μ+ e + e Hit Time (Time of Flight Corrected) [ns] 13

14 Requirements for Intrinsic Light-yield (photons/mev) pe 50 pe 100 pe A 50-m WbLS detector: T k+ = 90MeV 20% coverage with 25% QE photocathode Deep underground >3000 m.w.e. Fast decay at 12ns 5 Attenuation Length (m) 50 14

15 WbLS for other Physics Compton Edge, AU T2K ND-280 Tunable light, linear? WbLS 2014 WbLS LS % in Water 3-D medical Imaging and TOF- PET (10% Gd- or Pb-WbLS) WATCHMAN 15

16 the U.S. to host a large water Cherenkov neutrino detector, as one of three additional high-priority activities, to complement the LBNF liquid argon detector, unifying the global long-baseline neutrino community to take full advantage of the world s highest intensity neutrino beam. The placement of the water and liquid argon detectors would be optimized for complementarity. This approach would be an excellent example of global cooperation and planning P5 (Scenario C) Feasibility of a large water Cherenkov scintillation detector? 16

17 Scintillation at 100 photons per MeV 3 low Intensity Proton Beams Low-intensity Proton-beam 3 runs Charge (PE/MeV) 10 4 Material Samples T1 (white Teflon) Charge (in PE/MeV) * Beam Energy (MeV) 2 Detectors Water Sample WbLS1 Sample WbLS2 Sample 210 MeV de/dx ~ K+ from PDK 475 MeV Cerenkov threshold 2 GeV MIP Water WbLS 1 WbLS 2 LS pure water 0.4% LS 0.99% LS pure LS Tub 1 Tub 2 PTFE (highly reflective white Teflon) Aluminum coated with black Teflon 17

18 Optical Model LAB -350nm Extinction coefficient (scattering + absorption) 2-m system to verify the extinction length UV spectrometer (10-1 to mitigate Fresnel reflection) to measure molar extinction coefficient of each component of WbLS A = ( 1 c c c 3 + ) Absorbance LS mea. 10cm LS cal. 10cm wavelength (nm) Absorption is predictable Scattering is complicated Rayleigh, surface (interface) tension, etc. Optical model successfully predicts the attenuation length of LAB + PPO + bis-msb (verified by 2m system) 18

19 Scattering needs improvement (work-in-progress) Coefficient (1/cm) Adding Gd and PPO further increase the scattering need optimization Gd-WbLS scattering LAB+PPO WbLS LS component absorption (+/ ) Gd-WbLS extinction WbLS scattering Water-extinc Wavelength (nm) 19

20 Tug of War Need additional tension-reduction reagent to reduce the scattering Balance between absorption and scattering Additional component higher absorption 20

21 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 10 5 mg/l Stable in acrylic, PP, some polycarbonate, etc. Oil-like WbLS doesn t require circulation (e.g. Daya Bay, SNO+, PROSPECT) Might not need circulation with careful selection of vessel and materials-in-contact Passing 0.1 micron filter Radon daughters? To be tested under WATCHMAN 21

22 Material Compatibility A well-equipped compatibility program at BNL serving to several experiments (SNO, SNO+, Daya Bay, PROSPECT, LBNEwater, T2K) 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) 0.05 acrylic untreated /7/2014 3/13/2014 3/24/2014 3/31/2014 Abs acrylic in ethanol Wavelength (nm) % WbLS optically stable for acrylic, PP, PFA (other materials in preparation) Atomic force microscopy (AFM) high-resolution scanning 22

23 Summary SNO+ (90% WbLS with Te) PROSPECT (~90% WbLS with Li-6) 3-D Imaging SBIR (5% WbLS) T2K ND-280 (10-15% WbLS) WATCHMAN (1% WbLS) Principals of WbLS detection and isotope loading have been proven; applied to several ongoing and/or newly proposed experiments already. The developments of a large WbLS detector with fast timing and Cherenkov and Scintillation separation (Advanced Scintillator Detector Concept) for multi-physics searches are ongoing. BNL 1-t Daya Bay 20-t ASDC? WATCHMAN 3kt 23

24 Advanced Scintillation Detector Concept A large WbLS detector with fast timing for Cherenkov and Scintillation separation NNN2014 LAPPD: M. Sanchez Event Reconstruction: A. Mastbaum ASDC: G. Orebi Gann Large science community with interest and experience WbLS Workshop, May 17-18, 2014 (LBNL) 27 participants, 17 talks Concept paper available arxiv: authors (potential PIs), 22 institutions (US and Germany) New involvement welcome! Please contact G. D. Orebi Gann, B. Svoboda, E. Blucher, J. R. Klein, M. Yeh) 24

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