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

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

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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

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SLIDE 1

Scintillation Detector

Minfang Yeh (BNL)

PX workshop 2012

  • General introduction and physics of liquid scintillator
  • Metal-loaded liquid scintillator
  • Future liquid scintillator
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SLIDE 2

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

Typical Cerenkov and Scintillation Detectors

2

Cerenkov (Super-K)

0ββ, geo-, reactor-, beam physics ND proton decay, supernovae (Gd),beam physics FD ~kt Detector ~>50kt Detector

~100% LS ~20% LS

Scintillator (Daya Bay)

PX workshop 2012 M. Yeh

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SLIDE 3

Main Neutrino Interactions in Liquid Scintillator

  • + p
  • + 12C
  • 12B

12C

  • + 12C
  • 12

12C

  • + 12C
  • 12

* 12

  • PX workshop M. Yeh

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
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SLIDE 4

BNL Liquid Scintillator Development Facility

PX workshop 2012 M. Yeh

4

  • ability to catch ionization radiation
  • photon-transferring mechanisms once

excited (S/F/S)

  • Collaboration between Physics and

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

scintillators with high light-yield, long attenuation length and low flammability.

  • Capability of purifying and

synthesizing materials in-house and of controlling the chemical processes.

  • M. Yeh, Review of Metal-loaded Liquid Scintillator for Neutrino Physics, IJMPB (in prep.).

Scintillation mechanism

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SLIDE 5

Comparisons of Liquid Scintillators for Neutrino Expt’s

first identified by SNO+

PX workshop M. Yeh

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SLIDE 6

Past & Present Liquid Scintillator experiments

PX workshop M. Yeh

Experiment Scintillator Mix

Palo Verde

40% PC + 60% Mineral oil

CHOOZ

50% paraffinic liquid + IPB (isopropylbiphenyl)

Borexino

PC

LENS

LAB (PC)

MiniBOONE

MO

Daya Bay

LAB

SNO+

LAB

RENO

LAB

Double-CHOOZ

20%PXE + 80%dodecane

KamLAND2

20% PC + 80%dodecane

NOvA

5% PC + 95% MO

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SLIDE 7

Possible Future Liquid Scintillator Experiments

PX workshop 2012 M. Yeh 7

Newly Proposed Experiments (selected) Accelerator-based LENA OscSNS IsoDAR Reactor-based Daya Bay-II, RENO-II SCRAAM, Stereo, NIST -sources Ce-LAND LENS-Sterile

  • LS not decided; but

LAB is the favor

  • Gd-loaded for most

reactor expt’s

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SLIDE 8

Metal-loaded LS for Physics

Reactor  Solar Others

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

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SLIDE 9

Inverse Beta Decay Detection with Gd

 Ethreshold = 1.8 MeV  ‘Large’ cross section σ~10-42 cm2  Distinctive coincidence signature in

a large liquid scintillator detector

Cowan & Reines, Savannah River 1956

Ev - 0.8 MeV

PX workshop M. Yeh

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SLIDE 10

10

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 mbb

limit of ~20 meV would exclude Majorana neutrinos in an inverted hierarchy. Nd-LS

  • 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

PX workshop 2012 M. Yeh

Double-beta Decay using Nd

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SLIDE 11

PX workshop M. Yeh

  • 8% Indium loaded LS meets the experiment needs
  • micro-LENS is ongoing in Kimberton mine with mini-LENS in preparation
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SLIDE 12

How to make a clean and stable metal- loaded LS?

  • Synthesis procedure
  • Purification (radioactive & optical)
  • QA/QC

PX workshop M. Yeh

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SLIDE 13
  • Ex. of Gd-LS production at Daya Bay:
  • Gd-LS production done in 3 months
  • >3-yrs R&D and >1-yr 1-t prototype

monitoring on Gd-LS stability

  • Optical improvement and U/Th removal
  • QA/QC during and after production

LS storage liquid production Gd‐LS storage 4‐t Gd‐LS batch Self-scavenge, PH-controlled Gd salt purification

+

TMHA

Low flash point, compatible light- yield, know-how production, high compatibility

PX workshop M. Yeh

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SLIDE 14

Self-scavenge Gd purification

PX workshop M. Yeh

  • U/Th removed to < 0.1 ppb
  • Optical improvement by 2x from

300-450nm

M. Yeh et al. NIM A 618 (2010) 124–130

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SLIDE 15

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

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SLIDE 16

Absorption Length Calculation

PX workshop M. Yeh

Gd-LS LS LAB

 (m)

20.9 20.4 22.8

Water has long attenuation lengths (136 – 200m)

  • bserved by Super-K, SNO, etc.; dominated by scattering

<350nm

~10m at 0.004

UV + 1/e LBNE simulation match with the 2-m measurement very well!

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SLIDE 17
  • Abs. at 0.002 ~ 20m

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
  • Light-yield emission agrees within 1% (Fluorescence

Spectroscopy)

PX workshop M. Yeh

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SLIDE 18

Liquid scintillator Options for future experiments

  • Binary liquid scintillator
  • Singular liquid scintillator
  • Water-based liquid scintillator

PX workshop M. Yeh

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SLIDE 19

Option-1: Binary scintillating liquid system

Linear Alkylbenene + dodecane or mineral oil

PX workshop M. Yeh

Pseudocumene Linear Alkylbenzene

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SLIDE 20

Density Matching and Solvent Purity are the keys to the stability of binary system

PX workshop M. Yeh

  • 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.

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SLIDE 21

Option-2 singular liquid scintillator

LAB + PPO (3g/L) + bis-MSB (15 mg/L) ~ 10,000 ’s / MeV

PX workshop M. Yeh

nm AU

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SLIDE 22

Option-3: Water-based Liquid Scintillator

PX workshop M. Yeh

  • 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
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SLIDE 23

WbLS(PPO) between 2 – 4 ns

10-MeV e- beam at LEAF Time-resolved fluorescence system

PX workshop M. Yeh

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SLIDE 24

WbLS Attenuation Length close to pure water after 400nm

PX workshop 2012 M. Yeh 24

  • UVs of 18-MΩ water and

WbLS normalized to Super-K abs. curve.

  • Mean-free absorption

length calculated by LBNE water attenuation simulation (developed for Compatibility test).

  • Need large-scale verification

0.001 0.01 0.1 1 10 100 100 300 500 700 900 Absorption Coefficient (m-1) Wavelength (nm)

WbLS-2012 Daya Bay LS Super-K scattering + absorption R7081 PMT QE

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SLIDE 25

0.001 0.01 0.1 1 10 100 100 300 500 700 900 Absorption Coefficient (m-1) Wavelength (nm)

WbLS-2012 Daya Bay LS Super-K scattering + absorption WbLS-2012 emission at 265nm PPO emission at 310nm MSB emission at 365nm R7081 PMT QE

Emission at the PMT sensible region is very clean

PX workshop 2012 M. Yeh 25

  • The fluor/shifter

transmission needs to be

  • ptimized.
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SLIDE 26

200 400 600 800 1000 1200 1400 1600 1800 2000 200 400 600 AU Channel

H2O+Carbostyril-124 WbLS-2012

WbLS Scintillation vs. Cerenkov (Cs-137)

  • Cerenkov increases by ~4x using

Carbostyril-124 (SNO)

  • A ratio of 5:1 for scintillation vs. Cerenkov

PX workshop M. Yeh

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SLIDE 27

WbLS at NSRL high-energy particle-beam in 2011

  • 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.).

Figure 2: The instantaneous intensity in Hz as a function of time in spill in ms.

preliminary

PX workshop M. Yeh

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SLIDE 28

Scintillation light at 90 s/MeV

  • ne event No Cut
  • select different timing

windows for k+ and μ+ events

  • PX workshop M.

Yeh

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SLIDE 29

Select the k+ Timing Window (0 13ns)

  • scintillation light only
  • no Cerenkov ring

PX workshop M. Yeh

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SLIDE 30

Select the µ+ window (13 22ns)

clean μ-rings can be identified among scintillation

PX workshop M. Yeh

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SLIDE 31

Sensitivity of WbLS for PDK+

PX workshop 2012 M. Yeh

31

  • Event Signal-like:

Prompt

  • K+ scintillation

Delay

  • + and + scintillation
  • scintillation
  • Cerenkov rings from , , , Michel electron, etc.
  • Event Selection Rules
  • 12.8 ns between prompt and delay.
  • No ring in Prompt.
  • Energy Cut on prompt event.
  • Rings in delay
  • Energy cuts in delay with rings
  • etc…
  • 10-yr run could reach a sensitivity of 1034 for the

PDK+ mode).

  • Compare to SK (170 events in

1489 days), the 3-fold coincidence cuts down to ~5/y; PSD/Michel position cut can further suppress the

  • bkg. event to 0.25/y.
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SLIDE 32

A new way of loading hydrophilic metallic ions (Li, Ca, Te, etc) in scintillator

  • Double-beta decay
  • Reactor neutrino
  • Geo neutrino
  • Supernovae neutrino

PX workshop M. Yeh

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SLIDE 33

First DBD isotope in WbLS

PX workshop 2012 M. Yeh

33

1 10 100 1000 10000 200 400 600 800 1000 AU Channel

0.5% X-WbLS + PPO 0.5% X-WbLS + PPO/MSB LAB + PPO

X-WbLS

  • Efforts to load certain metallic-ions in pure LS

(=80%)

  • Quick and straight in preparation of X-WbLS

(=100%)

X-LS

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SLIDE 34

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

Typical Cerenkov and Scintillation Detectors

34

Cerenkov (Super-K)

0ββ, geo-, reactor-, beam physics ND proton decay, supernovae (Gd),beam physics FD ~kt Detector ~>50kt Detector

~100% LS ~20% LS

Scintillator (Daya Bay)

PX workshop 2012 M. Yeh

Cerenkov & Scintillation WbLS Organometallic-ion WbLS

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SLIDE 35

PX workshop M. Yeh

LS reactivity (compatibility) favors LAB

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SLIDE 36

20 40 60 80 100

200 261 322 383 444 505 566 627 688 749 810 871 932 993 1054

T%

nm

glass1 BC490_on_glass1 silica3 BC490_in_xylenes_onSilica3 glass3 BC490_in_xylenes_onGlass3

Liquid Scintillation Veto film

36

  • current experience with LS veto-film

(a project in collaboration with LNGS) to produce -thin, Teflon- based films targeting surface /β for background reduction.

  • Related applications to LAr light

collection.

  • Current PVT (polyvinyl toluene) –

based polymer deteriorates under UV-light; questionable to be used under cryogenic condition.

  • Current toluene-TPB (tetraphenyl

butadiene) combination is not the best match for LAr emission at 128nm.

μm-thin veto film Under UV

PX workshop 2012 M. Yeh

1 10 100 1000 10000 100000 100 200 300 400 500

channel

Pu bkg Cs Pu_attenuate

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SLIDE 37

Summary

  • Liquid scintillator continues to play a key role for neutrino detection in

(non)accelerator, reactor, double-beta decay experiments.

  • There are several liquid options for the future detector; depending on the

physics requirements and costs.

  • The technology of meal-loaded LS is well developed; and its M%,

attenuation length, and photon-production are tunable as needed.

  • The synthesis technology, material compatibility, and cost of production

& purification of scintillator have been worked out and demonstrated to be stable.

  • WbLS with scintillation & Cerenkov detections is an excellent medium

for proton decay (and other physics) and can be used for neutron tagging (enhanced by Gd loaded) .

  • A cost-effective large detector as well as veto system for future experiment

PX workshop M. Yeh

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SLIDE 38

PX workshop M. Yeh