Scintillation Detector General introduction and physics of liquid - PowerPoint PPT Presentation

Scintillation Detector • General introduction and physics of liquid scintillator • Metal-loaded liquid scintillator • Future liquid scintillator Minfang Yeh (BNL) PX workshop 2012

Typical Cerenkov and Scintillation Detectors 180 160 Mean Absorption Length (m) Cerenkov (Super-K) 140 proton decay, supernovae 120 (Gd),beam physics FD 100 ~>50kt Detector 80 ~kt Detector 0  ββ , geo-  , 60 reactor-  , beam 40 physics ND 20 Scintillator (Daya Bay) 0 ~100% LS ~20% LS 100 1000 10000 Photon/MeV 2 PX workshop 2012 M. Yeh

Main Neutrino Interactions in Liquid Scintillator �   � + p � �  � + 12 C 12 B 12 C � � �  � + 12 C 12 12 C � �  *  12  � + 12 C 12 �  �  � � J.M.A. Winter (TU Munchen)   � �  Excellent detection medium for neutrino in MeV range; need NC background reduction in GeV range  Profound physics program for Solar-, Geo-, Reactor- &, Supernova-Neutrinos,Neutrino Oscillation, Proton Decay.  Different LS combinations to meet the need of various physics PX workshop M. Yeh

BNL Liquid Scintillator Development Facility • Collaboration between Physics and Scintillation mechanism Chemistry at BNL with expertise in low-background counting, organic scintillators, and in particular metal- loaded organic scintillator • Interest of neutrino and neutron detectors (Daya Bay, SNO+, LENS) • Investigation of a large variety of liquid scintillators • PC, PCH, DIN, PXE, LAB • Metal-loaded and water-based M. Yeh, Review of Metal-loaded Liquid Scintillator for Neutrino Physics, IJMPB (in prep.). scintillators with high light-yield, long ability to catch ionization radiation • photon-transferring mechanisms once • attenuation length and low excited (S/F/S) flammability. • Capability of purifying and synthesizing materials in-house and of controlling the chemical processes. 4 PX workshop 2012 M. Yeh

Comparisons of Liquid Scintillators for Neutrino Expt’s first identified by SNO+ PX workshop M. Yeh

Past & Present Liquid Scintillator experiments Experiment Scintillator Mix Palo Verde 40% PC + 60% Mineral oil 50% paraffinic liquid + IPB CHOOZ (isopropylbiphenyl) Borexino PC LENS LAB (PC) MiniBOONE MO Daya Bay LAB SNO+ LAB RENO LAB Double-CHOOZ 20%PXE + 80%dodecane KamLAND 2 20% PC + 80%dodecane NOvA 5% PC + 95% MO PX workshop M. Yeh

Possible Future Liquid Scintillator Experiments Newly Proposed Experiments (selected) Accelerator-based LENA • LS not decided; but OscSNS LAB is the favor • Gd-loaded for most IsoDAR reactor expt’s Reactor-based Daya Bay-II, RENO-II SCRAAM, Stereo, NIST  -sources Ce-LAND LENS-Sterile PX workshop 2012 M. Yeh 7

Metal-loaded LS for Physics Reactor  Solar M. Yeh, Review of Metal-loaded Liquid Scintillator for Neutrino Physics, IJMPB (in preparation). Others PX workshop M. Yeh

Inverse Beta Decay Detection with Gd  E threshold = 1.8 MeV  ‘Large’ cross section σ ~10 -42 cm 2  Distinctive coincidence signature in a large liquid scintillator detector E v - 0.8 MeV Cowan & Reines, Savannah River 1956 PX workshop M. Yeh

Double-beta Decay using Nd Nd-LS Searching for 0  ββ -decay to answer: whether neutrinos are Dirac or Majorana particles • probe neutrino masses at the level of tens of meV; A m bb • limit of ~20 meV would exclude Majorana neutrinos in an inverted hierarchy. SNO+ is the only metal-loaded liquid • scintillation detector. Flexible and easy scale-up • Any hydrophilic DDB isotopes that cannot • be done in pure LS; NOW is possible. Installation and production in FY13 • 10 PX workshop 2012 M. Yeh

• 8% Indium loaded LS meets the experiment needs • micro-LENS is ongoing in Kimberton mine with mini-LENS in preparation PX workshop M. Yeh

• Synthesis procedure • Purification (radioactive & optical) • QA/QC How to make a clean and stable metal- loaded LS? PX workshop M. Yeh

Gd ‐ LS storage LS storage liquid production 4 ‐ t Gd ‐ LS batch Ex. of Gd-LS production at Daya Bay : Gd-LS production done in 3 months • Low flash point, compatible light- >3-yrs R&D and >1-yr 1-t prototype • yield, know-how production, high monitoring on Gd-LS stability compatibility Optical improvement and U/Th removal • QA/QC during and after production • Self-scavenge, PH-controlled Gd salt purification TMHA + PX workshop M. Yeh

Self-scavenge Gd purification M. Yeh et al. NIM A 618 (2010) 124–130 • U/Th removed to < 0.1 ppb • Optical improvement by 2x from 300-450nm PX workshop M. Yeh

Complexing acid and PPO purifications  Purification is a must for optical and stability improvements.  LAB produced specially by the vendor.  PPO purified by re-crystallization after washes (can also purified by mixing in PC or LAB by direct distillation)  Gd-complexing ligand purified by thin-film vacuum distillation. heavy potion removed from the ligand solvent by 3x in 300-500nm PX workshop M. Yeh

Absorption Length Calculation ~10m at 0.004 UV +  1/e LBNE simulation match with Gd-LS LS LAB the 2-m measurement  (m) 20.9 20.4 22.8 very well! Water has long attenuation lengths (136 – 200m) observed by Super-K, SNO, etc.; dominated by scattering <350nm PX workshop M. Yeh

QA/QC and AD Identification • Stability All 6 ADs: • [Gd] agrees within 0.16% • [H] agrees within 0.17% (Combustion analysis) • [Gd-LS]  ave. >20m Abs. at 0.002 ~ 20m • Light-yield emission agrees within 1% (Fluorescence Spectroscopy) PX workshop M. Yeh

• Binary liquid scintillator • Singular liquid scintillator • Water-based liquid scintillator Liquid scintillator Options for future experiments PX workshop M. Yeh

Option-1: Binary scintillating liquid system Linear Alkylbenene + dodecane or mineral oil Linear Alkylbenzene Pseudocumene PX workshop M. Yeh

Density Matching and Solvent Purity are the keys to the stability of binary system  For the bottle with 2 phases, the top layer is light mineral oil at 80% with 0.00529%Gd and the bottom layer is PC at 20% with 0.01149%Gd.  Others of Gd in PC and DD with and without shifters have been stable since 2005. PX workshop M. Yeh

Option-2 singular liquid scintillator LAB + PPO (3g/L) + bis-MSB (15 mg/L) ~ 10,000  ’s / MeV AU nm PX workshop M. Yeh

Option-3: Water-based Liquid Scintillator  Cost-saving for larger detector (see talk in cost-effective detector session)  Clean Cerenkov cone with scintillation at few hundreds of photons per MeV (tunable)  Fast pulse and long attenuation length with minimum ES&H concerns  A new technology ready to use: • Excellent detection medium for proton decay; and other physics • Easy to be handled for large detector • Gd-soluable • A economic large veto solvent PX workshop M. Yeh

WbLS(PPO) between 2 – 4 ns Time-resolved fluorescence system 10-MeV e - beam at LEAF PX workshop M. Yeh

WbLS Attenuation Length close to pure water after 400nm 100 WbLS-2012 Daya Bay LS 10 Super-K scattering + absorption Absorption Coefficient (m -1 ) R7081 PMT QE 1 0.1 UVs of 18-M Ω water and • WbLS normalized to Super-K abs. curve. 0.01 Mean-free absorption • length calculated by LBNE water attenuation 0.001 simulation (developed for 100 300 500 700 900 Compatibility test). Wavelength (nm) PX workshop 2012 M. Yeh 24 Need large-scale verification •

Emission at the PMT sensible region is very clean 100 WbLS-2012 Daya Bay LS Super-K scattering + absorption WbLS-2012 emission at 265nm 10 PPO emission at 310nm Absorption Coefficient (m -1 ) MSB emission at 365nm R7081 PMT QE 1 0.1 0.01 The fluor/shifter • transmission needs to be optimized. 0.001 100 300 500 700 900 Wavelength (nm) PX workshop 2012 M. Yeh 25

WbLS Scintillation vs. Cerenkov (Cs-137) 2000 1800 H2O+Carbostyril-124 1600 WbLS-2012 1400 1200 Cerenkov increases by ~4x using • Carbostyril-124 (SNO) AU 1000 A ratio of 5:1 for scintillation vs. Cerenkov • 800 600 400 200 0 0 200 400 600 Channel PX workshop M. Yeh

WbLS at NSRL high-energy particle-beam in 2011 preliminary Figure 2: The instantaneous intensity in Hz as a function of time in spill in ms. 1-GeV proton beam • Daya Bay sees ~32:1 of Scintillation vs. • Cerenkov in pure LS. WbLS obtains ~1/3 of LS light (10:1 • compared to water-filled) Reinvestigate with 100 – 300 MeV p-beam • this fall (LDRD funded, Hide et. al.). PX workshop M. Yeh

Scintillation light at 90 s/MeV � � � � one event No Cut • select different timing • windows for k + and μ + events PX workshop M. Yeh

Select the k + Timing Window (0 13ns)  scintillation light only  no Cerenkov ring PX workshop M. Yeh

Select the µ + window (13 22ns) clean μ -rings can be identified among scintillation PX workshop M. Yeh