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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.