WbLS measurements at BNL David Jaffe 1 BNL 20140516 1 cohort: - - PowerPoint PPT Presentation

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WbLS measurements at BNL David Jaffe 1 BNL 20140516 1 cohort: - - PowerPoint PPT Presentation

Oct 13, 2022 269 likes •443 views

WbLS measurements at BNL David Jaffe 1 BNL 20140516 1 cohort: L.J.Bignell, D.Beznosko, M.V.Diwan, S.Hans, S.Kettell, R.Rosero, H.Themann, B.Viren, E.Worcester, M.Yeh, C.Zhang 1 / 16 Light production in water, LS & WbLS 1. Cerenkov

slide-1
SLIDE 1

WbLS measurements at BNL

David Jaffe 1 BNL 20140516

1cohort: L.J.Bignell, D.Beznosko, M.V.Diwan, S.Hans, S.Kettell, R.Rosero,

H.Themann, B.Viren, E.Worcester, M.Yeh, C.Zhang

1 / 16

slide-2
SLIDE 2

Light production in water, LS & WbLS

  • 1. ˇ

Cerenkov (point source 2, directional, prompt)

1.1 Light yield is calculable: N ≈ (path length) × N0(sin2 θC) 1.2 Spectrum LY(λ) ∝

1 λ2 1 1−β2n(λ)2

  • 2. Scintillation (point source, isotropic, extended in time)

2.1 Light yield proportional to energy deposit, modulo quenching. Must be measured. 2.2 Narrow spectrum

  • 3. Absorption & re-emission (possibly diffuse source, isotropic,

extended in time)

3.1 Optical γ from ˇ Cerenkov or scintillation can be absorbed & re-emitted by medium 3.2 Has potential to shift ˇ C γ from VUV to visible to a typical photodetector (eg. bialkalai PMT)

LY for these processes is comparable for ≤ 10% concentration WbLS. Disentangling them and understanding the details of λ-dependence is tedious.

2As opposed to diffuse source 2 / 16

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SLIDE 3

λ-dependence (arbitrary norm. except absorption length)

150 200 250 300 350 400 450 500 550 600 650 0.00001 0.0001 0.001 0.01 0.1 1 10 100 WbLSEAbsorptionELengthEl1/mmQ CerenkovEEmissionESpectrumyE475EMeVEProtons WbLSEEmission PhotomultiplierEQuantumEEfficiency CerenkovEEmissionESpectrumyE2EGeVEProtons

Wavelength (nm)

3 / 16

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SLIDE 4

Measurements at BNL

The following pages have details of two sets of measurements in a low energy proton beam.

  • 1. NSRL 3 run 12C: Light yield measured for water, LS, 0.4%

and 1% WbLS, investigate quenching. Result: LY approximately linear with LS concentration

  • 2. NSRL run 13A: Absolutely calibrate 1% WbLS LY against

ˇ Cerenkov LY Result: LY of 1% WbLS is ≈ 110 optical photons/MeV (±10% uncertainty) Goals:

  • 1. Determine increase in sensitivity of a SK-like detector with

WbLS to p → K +¯ ν.

  • 2. Disentangle competing light production processes.

3NASA Space Radiation Laboratory at BNL, of course. 4 / 16

slide-5
SLIDE 5

Early MC estimate of p → K +¯ ν sensitivity with 1%-WbLS-based detector

10

Projected Sensitivity

Year 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 Lifetime Sensitivity (90% C.L.)

33

10

34

10

35

10

+

+ K ! " p

Super-K WbLS 22.5 kt

τ(p → K+¯ ν) > 2 × 1034y at 90% C.L. in 10 years

5 / 16

slide-6
SLIDE 6

NSRL12C Beam setup (identical liquids in each tub)

Not to scale Proton beam

15cm

0.635cm

15cm

0.635cm VC H1 H2 H3

H1,H2,H3 plastic scint. hodoscope 2cmX2cmX0.5cm Trigger: H1•H2

Reflectivity>95% PTFE tub “T1” Reflectivity<10% Al tub “T2”

A2 A1

NSRL beam monitor: A1•A2 A1 (A2) is 1cm2 (2 cm2), 2mm thick plastic scint.

T1,T2 Hamamatsu R7723 2”PMTs CAEN V1729A FADC 12bit,1GSPS

6 / 16

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SLIDE 7

NSRL12C: PTFE tub with PMT

7 / 16

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SLIDE 8

NSRL12C: Incident and deposited energies

(MeV) Incident Incident Energy Beam β energy deposited energy T1 T2 T1 T2 T1 T2 Sample 210 0.57 0.45 202 113 70 113 Water, WbLS 210 0.57 0.47 202 124 59 124 LS 475 0.75 0.72 470 421 39 42 Water, WbLS 475 0.75 0.73 470 427 34 36 LS 2000 0.95 0.95 1996 1962 28 28 Water, WbLS 2000 0.95 0.95 1996 1966 24 24 LS

◮ p → K +¯

ν: βK = 0.57 ⇒ Tp = 210MeV

◮ Tp = 475MeV is just above proton ˇ

Cerenkov threshold

◮ Tp = 2000MeV ≈ minimum-ionizing (max NSRL beam energy) ◮ Calculated incident velocities, incident and deposited energies in

MeV for “T1” (PTFE tub) and “T2” (Aluminum tub) using NIST’s proton stopping power and range tables (PSTAR). Estimated uncertainty is a few MeV.

8 / 16

slide-9
SLIDE 9

12C results: LY vs deposited energy

Edep(MeV) 20 30 40 50 60 70 T1_Charge(PE)/Edep(MeV)

  • 2

10

  • 1

10 1 10

2

10 T1_Charge(PE)/Edep(MeV) vs Edep(MeV)

water wbls1 wbls2 ls

White PTFE tub. PE/MeV vs MeV deposited.

Edep(MeV) 20 40 60 80 100 120 140 T2_Charge(PE)/Edep(MeV)

  • 2

10

  • 1

10 1 10 T2_Charge(PE)/Edep(MeV) vs Edep(MeV)

wbls1 wbls2 ls

Black PTFE-coated Al tub. PE/MeV vs MeV deposited.

9 / 16

slide-10
SLIDE 10

12C results: Normalized PE/MeV vs LS concentration

LS-concentration(%) [Water at 0.001% for plot]

  • 3

10

  • 2

10

  • 1

10 1 10

2

10 Normed PE/MeV

  • 3

10

  • 2

10

  • 1

10 1

Normed PE/MeV vs LS-concentration(%) [Water at 0.001% for plot]

475 T1 2000 T1 T2 210 T2 475 T2 2000

  • 1. LY approximately

proportional to concentration for 210, 475 MeV.

  • 2. 2000 MeV shows effect of

ˇ Cerenkov contribution PE/MeV (normalized to LS PE/MeV) vs LS concentration for proton beam data.

10 / 16

slide-11
SLIDE 11

Table of results

Ratio(%) to 100% concentration Conc 210 MeV 475 MeV 2000 MeV (%) T1 T2 T1 T2 T1 T2 0. — — 0.07 ± 0.02 — 1.89 ± 0.21 — 0.4 — 0.19 ± 0.02 0.29 ± 0.02 0.32 ± 0.02 1.95 ± 0.20 2.18 ± 0.24 1.0 — 1.22 ± 0.08 0.82 ± 0.05 1.32 ± 0.08 2.16 ± 0.20 3.57 ± 0.40 100 — 100 ± 10.80 100 ± 6.79 100 ± 10.68 100 ± 10.22 100 ± 10.64

  • 1. T1 (white PTFE) 210 MeV LS inaccurate: PMT saturated
  • 2. T2 (black PTFE) water data unreliable: PMT re-positioned
  • 3. 2000 MeV data complicated by ˇ

Cerenkov contribution

11 / 16

slide-12
SLIDE 12

Compare NSRL12C and Compton-edge data

concentration(%) [Water at 0.001% for plot]

  • 3

10

  • 2

10

  • 1

10 1 10

2

10 Normed Light Yield

  • 3

10

  • 2

10

  • 1

10 1

Normed Light Yield vs concentration(%) [Water at 0.001% for plot]

T1 475 Normed PE/MeV vs LS-concentration(%) [Water at 0.001% for plot] T1 2000 Normed PE/MeV vs LS-concentration(%) [Water at 0.001% for plot] T2 210 Normed PE/MeV vs LS-concentration(%) [Water at 0.001% for plot] T2 475 Normed PE/MeV vs LS-concentration(%) [Water at 0.001% for plot] T2 2000 Normed PE/MeV vs LS-concentration(%) [Water at 0.001% for plot] Normalized LY vs LAB concentration in CX Normalized LY vs LAB concentration in WbLS

Compare relative light yield of proton beam data with preliminary Compton-edge data for WbLS and LAB in cyclohexane(CX).

  • 1. In WbLS, light yield is

proportional to concentration.

  • 2. In cyclohexane, light yield is

higher at low concentrations.

12 / 16

slide-13
SLIDE 13

NSRL13A setup schematic

$

./01,*'2,31..,'456

  • 1. External 2 × 2 cm2 plastic scintillator hodoscopes define beam

into yellow region.

  • 2. Dimensions selected so that ˇ

C ring from incident proton fully illuminates downstream PMT.

  • 3. Liquids: water and 1% WbLS
  • 4. Beam energies: 475 and 2000 MeV
  • 5. Detector can be rotated by 180◦ for systematics control.
  • 6. Detector is black ABS plastic, reflectivity < 10%

13 / 16

slide-14
SLIDE 14

NSRL13A expected and actual results

Beam Expected Actual (in photo-electrons) Energy PMT PMT PMTA PMTB PMTB PMTA (MeV) 4 Liquid DS US DS US DS US 2000 Water NC 42.2 0.9 40.4 1.4 2000 1%-WbLS QC + Qs Qs 27.9 9.5 27.7 8.1 475 Water 1.4 1.1 1.3 1.0 475 1%-WbLS Ns Ns 6.4 5.5 6.6 5.6 Uncertainties: ±10% for > 2PE, ±20% otherwise.

QC = NC × (1 − Pa) and Qs = Ns + NCPaPr where Pa ∼ absorption prob. and Pr ∼ re-emission probability. Illustrative only, neglects λ-dependence of production, absorption, re-emission, transmission and detection efficiency. Complications:

  • 1. 475 MeV is not below proton ˇ

C threshold (Doh!)

  • 2. δ−ray production
  • 3. Non-zero reflectivity

4Deposited energies: ∼37 and ∼26.3 MeV for 475 and 2000 MeV, resp. 14 / 16

slide-15
SLIDE 15

NSRL13A interpretation of results

  • 1. A full Geant4-based simulation has been developed and

applied for the NSRL13A data.

  • 2. Combining results and taking into account the calculated

energy loss in the liquid, the scintillator light yield is 113(±10%) optical photons per MeV deposited.

  • 3. To first order,

Pa = 1 − NWbLS

DS

− NWbLS

US

NWater

DS

≈ 46% , in other words, approximately half of the photons in ˇ Cerenkov ring will be eliminated in the 1% WbLS. Comparison of simulation(hist) and data(points) for 475 MeV protons in 1%-WbLS

Charge Collected (Number of Photoelectrons) 5 10 15 20 25 30 35 40 Normalized Counts 0.02 0.04 0.06 0.08 0.1 0.12 0.14

15 / 16

slide-16
SLIDE 16

Next steps

  • 1. Unified analysis of NSRL12C and NSRL13A data with full

Geant4-based simulation.

  • 2. Measurement of decay-time distributions in NSRL12C,

NSRL13A data

  • 3. Measurement and simulation of WbLS attenuation length in 2

meter system

  • 4. Re-examination of p → K +¯

ν sensitivity

  • 5. Deployment of “1-ton-prototype”, a 995 mm ID, 1250 mm

internal height, 25.4 mm thick UVT acrylic vessel, for measurements with cosmics

16 / 16