Scintillator Detectors for Neutrino Physics

Transcription

1 Scintillator Detectors for Neutrino Physics Minfang Yeh Neutrino and Nuclear Chemistry, BNL Jinping Workshop, Tsinghua, June 5, 2015

2 BNL-Liquid Scintillator Development Facility A unique facility (since 2002) for Radiochemical, Cherenkov, and Scintillator (water-based and metal-doped) detectors for particle physics experiments. Daya Bay, SNO+, PROSPECT, LZ, WATCHMAN, THEIA (ASDC) Institutional collaboration welcome! 2

3 Cherenkov and Scintillator Detector Cherenkov (Gd): e.g. SK, SNO, WATCHMAN-I, HK Water-based Liquid Scintillator Water-Like WbLS Cher/Scin det. Oil-Like WbLS Isotope loading PROSPECT, SNO+, WATCHMAN-II, Theia Scintillator: e.g Daya Bay, D-Chooz, RENO, JUNO 3

4 Main Neutrino Interactions in Scintillator + p ; KamLAND v e + 12 C e 12 B 12 C e v e v + 12 C e 12 N 12 C e v v + 12 C v 12 C * 12 C Daya Bay v e v e SNO+ v p v p NoVA Borexino Excellent detection medium for neutrinos in MeV range Different LS combinations to meet the needs of various physics Profound physics applications in Solar-, Geo-, Reactor-, Supernova-Neutrinos, Neutrino Oscillation, Proton Decay 4

5 Liquid Scintillator Physics 0 ββ (e.g. SNO+, KamLAND- Zen) Reactor (e.g. Daya Bay, PROSPECT, JUNO) Other Applications (e.g. Nonproliferation, source -, LZ) 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, SNS, J- PARC-E56) 5

6 Isotope-doped Liquid Scintillator for Neutrino Physics and Other Applications Reactor Solar Others 6

7 Liquid Scintillators Stability, light-yield and optical transparency High flashpoint (PXE>DIN>LAB>PCH>PC) and low toxicity New generation scintillation water (next) Linear alkylbenzene (LAB) Cyclohexylbenzene (PCH) 1-phenyl-1-xylyl-ethane (PXE) Di-isopropylnaphthalene (DIN) 1,2,4-trimethylbenzene (PC) 7

8 Water-based Liquid Scintillator A new detection medium, bridging scintillator and water, motivated by Nucleon Decay Tunable scintillation light from ~pure water to ~organic: Water-like WbLS: A scintillation water with Cherenkov and Scintillation detection Oil-like WbLS: A novel technology for loading various isotopes, particularly for hydrophilic elements, in scintillator 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). 100 photons/mev; A.L.=20m A 50-m WbLS SK-like detector (100ph/MeV) T k+ = 90MeV 20% coverage with 25% QE photocathode Deep underground >3000 m.w.e. Fast decay at 12ns 8

9 WbLS Profermance A scintillation water with fast and optical transparent light that can explore both scintillation and Cherenkov channels. 10 T1 (white Teflon) Charge (in PE/MeV) Charge (PE/MeV) Water Sample WbLS1 Sample WbLS2 Sample LS Sample /30 Low intensity proton beams at 275, 475 (~E threshold ), and 2000 MeV 1 0 NSRL@BNL Beam Energy (MeV) 9

10 WbLS Optical Transmission Continue R&D s reduce scattering need large-scale measurements 10

11 THEIA Advanced Scintillation Detector Concept (ASDC) Workshop - May 17/18 (LBNL): 27 participants, 17 talks kton WbLS target High coverage with ultra-fast, high efficiency photon sensors Deep underground (e.g mwe Homestake) Complementary program to proposed LAr detector at LBNF (P5, Scenario-C) with comprehensive low-energy program Long-baseline physics (mass hierarchy, CP violation) Scale-up from Super-K Neutrinoless double beta decay Solar neutrinos (solar metallicity, luminosity) Supernova burst neutrinos & DSNB Concept paper - arxiv: : 50 WATCHMAN could be the next large Geo-neutrinos water Cherenkov detector Nucleon decay Source-based sterile searches 60m 11

12 Onwards for a THEIA detector (e.g. Jinping) Isotope loading 0νββ, solar, n-tagging Stability of Cocktail Purification Chemical and radioactive impurities Large scale circulation and operation Cherenkov/scintillation separation WbLS cocktail tuning Slow timing Cherenkov light yield Cherenkov light below 400nm being transferred Attenuation length Bench-top scale demonstrated; need long arm measurement or large demonstrator BNL 1-ton 12

13 WbLS Isotope Dopings Solubility, light-yield, optical transmission, and radiopurity (radiogenic and cosmogenic isotopes) are the keys 1. Oragnometallic-extraction in scintillator has been successfully applied to reactor detection (e.g. Daya Bay) Require a mixing ligand to bring inorganic metallic ions into organic liquid scintillator Additional discrimination for radioactive isotopes difficult for hydrophilic isotopes 2. A New metal-doped technology using water-base Liquid Scintillator principal (e.g. PROSPECT, SNO+, etc.) Suitable for ~most metallic ions less-selective isotope loading Require extensive purification for radiopurity Lead-doped scintillator calorimeter Solar neutrino Total-absorption radiation detector (Medical) Lithium-doped scintillator detector 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 Te-LS vs. Te-WbLS 13

14 Te-WbLS (SNO+) New water-based LS loading Te in scintillator Better UV (PMT region clear) Higher light-yield Stable for 1.5+yrs 0.3% Te is the baseline (phase-i); up to 5%Te stable is achieve Improve the optical and photon-yield at higher loading (>3%) toward a future ton-scale 0 ββ experiment (phase-ii) Te-loading up to 5% better light-yield than Nd-LS 14

15 6 Li-WbLS (PROSPECT) BNL + Yale New Li-doped WbLS with enhanced light-yield, optical better and PSD that has been stable over 1.5 years for PROSPECT Background investigations (20-L) at ORNL reactor site Plan to start full-scale 2-ton ND in 2015 Continue R&D for higher loading at ~0.15% (Geometry, capture time, etc.) 15

16 Cherenkov/Scintillation Separation Separation of fast Cherenkov from slow scintillation to allow directional cut optimize scintillation light (WbLS) slow scintillation component Timing measurement for Particle ID (i.e. SNO+, OscSNS, etc.) Some ongoing works at Tsinghua U. electrons LSND rejects neutrons by a factor of 100 at ¼ Cherenkov & ¾ Scintillation light (NIM A388, 149, 1997). Cherenkov is <5% of scintillation neutrons 16

17 Tunable LY for other WbLS Physics T2K ND-280 Tunable light, linear? 3-D medical Imaging for ion-beam therapy (5-10%WbLS) and TOF-PET (10%Pb-WbLS) WATCHMAN phase-ii 17

18 Fluor/Shifter Optimization abs (10cm) 3% Te% NOT more the better; need optimization Optical transparency decreases with increasing loading of isotopes Purification of all components to remove colored impurities Shift the emission light to optical-cleaner region (>450nm) where is still sensible for PMT % Increasing absorption Wavelength (nm) bis-msb red-shift perylene 18

19 Purification Double-pass Cobalt Colored Impurities: colored impurity that affects the stability and optical transmission (large detector, i.e. JUNO, ASDC) Radioisotopes: Naturally-occurred and cosmicactivated isotopes K reduction = (SNO+) Known for Cherenkov detector; but challenges for scintillation detector (online circulation?) Distillation, column separation, self-scavenging, solvent washing and recrystallization are developed; need large-scale and cost-effective setup (TM to industry) 19

20 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, polycarbonate Oil-like WbLS doesn t require circulation (e.g. Daya Bay, SNO+, PROSPECT) Water-like WbLS might not need circulation with careful selection of vessel and materials-in-contact Passing 0.1 micron filter Molecular Band Pass (EGADS) Nanofiltration (UC Davis) Ongoing test with bacteria test (BNL) 20

21 Material Compatibility A program that selects and screens the detector materials 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) BNL has a well-quipped facility for SNO, SNO+, Daya Bay, PROSPECT, LBNE-water, T2K acrylic untreated acrylic in ethanol 10% WbLS stable in acrylic, PP, PFA, etc Atomic Force Microscopy (AFM) 21

22 ASDC Planned Demonstrators Site Scale Target Timeline EGADS 200 ton Gd-H2O Exists ANNIE 1 ton Gd-H2O 2018 WATCHMAN 1 kton Gd-H2O 2018 UChicago benchtop LS Exists UCLA 1 ton LS 2015 UPenn 30L (Wb)LS Exists SNO+ 780 ton (Wb)LS 2016 LBNL benchtop WbLS Winter2014 BNL benchtop +1-ton (M+Wb)LS 2015 WATCHMAN-II 1 kton WbLS 2019? Jinping? 22

23 EGADS Gd loading and purification Neutron yield physics LAPPD fast timing Water-based Liquid Scintillator THEIA Te loading WbLS, Gd, LAPPD, HQE PMT full integration prototype at Jinping? from R&D to Physics WATCHMAN M. Yeh Each demonstrator and/or experiment exercises different R&D topics (details with timeline in back-up) Parallel developments will provide inputs to a future large detector (Theia) 23

24 Back-up Slides 24