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WATER-BASED LIQUID SCINTILLATOR LIGHT YIELD AND TIME PROFILE MEASUREMENTS

Sean Grullon Wb-LS LBNE Workshop Berkeley

May 17th, 2014

OVERVIEW

Broad physics potential for a Water-based liquid scintillator

Physics reach affected by the light yield, the scintillation timing, and relative scintillation/Cherenkov timing

Gauge possible light yields and timing profiles which are achievable at this early stage

Four candidate water-based liquid scintillator solvents (labeled wbLS1-wbLS4) from Minfang et al. at BNL in 2012. Updated sample (wbLS5) in 2014.

Light output and timing profiles of five candidate solvents measured at Penn

SOURCE

•One 0.1 μCi Sr90 source mounted below hollowed out SNO acrylic (~ 5 mL volume)

•Optically coupled to 2’’ HQE PMT trigger

Sr90 Source

Hollowed out cavity

DARK BOX MEASUREMENT SETUP

12’’ R11780 High Quantum Efficiency

Details of PMTs and DAQ

available in NIM A 712, 162-173

(2013)

WATER-BASED LIQUID SCINTILLATOR - TOTAL LIGHT OUTPUT

wbLS 1

wbLS 2

wbLS 3

wbLS 4

500,000 waveform

traces !

Gain 107 : 1.6 pC / p.e.

WATER-BASED LIQUID SCINTILLATOR - TOTAL LIGHT OUTPUT

wbLS 1

wbLS 2

wbLS 3

wbLS 4

500,000 waveform

traces !

Gain 107 : 1.6 pC / p.e.

wbLS 5: New 2014 sample

COMPARISON - “TRADITIONAL” LIQUID SCINTILLATOR

Linear Alkyl Beznene (LAB) + 2g/L fluor (PPO): Scintillator solvent for SNO+

~10,000 photons/MeV typical for pure liquid scintillators.

Light Yield = 10800 ± 574 Photons/MeV

500,000 waveform

traces 1.6 pC / p.e.

WATER-BASED LIQUID SCINTILLATOR - MEASURED LIGHT YIELDS

Scintillation Light yields a rough estimate.

Derived by scaling down well-measured LAB + 2g/L PPO intrinsic light yield and subtracting off Cherenkov component.

SAMPLE MEASURED P.E. : WBLS/WATER SCINTILLATION LIGHT YIELD

WbLS1 4.00 ± 0.06 ~300 photons/MeVWbLS2 2.71 ± 0.07 ~200 photons/MeVWbLS3 1.68 ± 0.09 ~110 photons/MeVWbLS4 1.52 ± 0.08 ~100 photons/MeVWbLS5 1.9 ± 0.09 ~125 photons/MeV

TIMING PROFILES - CHERENKOV/SCINTILLATION SEPARATION

Scintillation later than Cherenkov light

Is the timing resolution of current-gen PMTs good enough to discriminate between the two?

ANT 2013

TIMING PROFILE - WB-LS, SAMPLE 5

~4-5 ns separation

Late Pulsing

125 photons/MeV

Python module incorporating TSpectrum to extract photon

arrival times

TIMING PROFILE - WB-LS, SAMPLE 4

~4-5 ns separation

Late Pulsing

100 photons/MeV

Python module incorporating TSpectrum to extract photon

arrival times

TIMING PROFILE - WB-LS, SAMPLE 3

~4-5 ns separation

Late Pulsing

110 photons/MeV

TIMING PROFILE - WB-LS, SAMPLE 2

~4 ns separation

Late Pulsing

200 photons/MeV

TIMING PROFILE - WB-LS, SAMPLE 1

~2 ns separation

300 photons/MeV

CONCLUSIONS & OUTLOOK

water-based liquid scintillator solvent can give a factor 1.5 - 4 more light than a

Corresponds to a scintillation light yield between ~100-300 photons/MeV

Cherenkov/Scintillation light discrimination based on timing possible. Components separated by ~4 ns on average for prototype samples.

Determine light yield and timing requirements for different physics topics.

Could perform a detailed study of what % of Cherenkov light gets converted to scintillation light…

WATER-BASED LIQUID SCINTILLATOR - TOTAL LIGHT OUTPUT

wbLS 1

wbLS 2

wbLS 3

wbLS 4

500,000 waveform

traces !

Gain 107 : 1.6 pC / p.e.