Daya Bay IBD selec+on Henoch Wong UC Berkeley Joint DC-RENO-DYB - - PowerPoint PPT Presentation

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Daya Bay IBD selec+on Henoch Wong UC Berkeley Joint DC-RENO-DYB - - PowerPoint PPT Presentation

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Daya Bay IBD selec+on Henoch Wong UC Berkeley Joint DC-RENO-DYB workshop Seoul Na+onal University 16-19 Oct 2016 1 Daya Bay Nuclear Power Plant Mountains shield detectors from cosmic ray background Ling Ao I NPP Daya Bay NPP 2 2.9 GW th

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SLIDE 1

Daya Bay IBD selec+on

Henoch Wong UC Berkeley Joint DC-RENO-DYB workshop Seoul Na+onal University 16-19 Oct 2016

1

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SLIDE 2

16/10/16 Spectral Measurement of An+neutrino Oscilla+on at Daya Bay 2

Daya Bay Nuclear Power Plant

Mountains shield detectors from cosmic ray background

Ling Ao II NPP 2 2.9 GWth Daya Bay NPP 2 2.9 GWth Ling Ao I NPP 2 2.9 GWth

Entrance to Daya Bay experiment tunnels

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SLIDE 3

3

Daya Bay reactors Ling Ao reactors Ling Ao II reactors Daya Bay Near Hall (EH1) Ling Ao near Hall (EH2)

Water Hall

Far Hall (EH3)

LS Hall

Entrance

Construction tunnel Tunnel

Reactor power 6 × 2.9 GWth

Experiment Layout

Two near halls constrain reactor flux Far hall measures

  • scilla=on
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SLIDE 4

Daya Bay Advantages

4

Baseline Op+miza+on

  • Detector loca+ons op+mized to

known parameter space of |Δm2

ee|

  • Far site maximizes term dependent
  • n sin2 2θ13

Go strong, big and deep!

Daya Bay RENO Double Chooz

Reactor [GWth] Gd Target [tons] Depth [m.w.e] Double Chooz 8.6 16 (2 × 8) 300, 120 (far, near) RENO 16.5 32 (2 × 16) 450, 120 Daya Bay 17.4 160 (8 × 20) 860, 250 Large Signal Low Background

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SLIDE 5

Daya Bay Detectors

  • Nucl. Instrum. Meth. A 773, 8 (2015)

Gd-doped liquid scintillator LS Mineral Oil 192 8’’ PMT

Auto calibration units

  • Nucl. Instrum. Meth. A 811, 133 (2016)

An+neutrino Detector (AD) Muon Veto System Two op+cally separated water Cherenkov system (IWS) (OWS)

5

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SLIDE 6

Quick Comparison of An+neutrino Detector

6

  • Gd-doped

liquid scintillator LS Mineral Oil 192 8’’ PMT

  • Nucl. Instrum. Meth. A 811, 133 (2016)

192 8-inch PMT 2x reflectors on top+boiom LAB based LS 354 10-inch PMT LAB based LS 390 10-inch PMT PXE/Dodecane based LS

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SLIDE 7

Quick Comparison of Muon Veto System

7

  • Nucl. Instrum. Meth. A 773, 8 (2015)

192 8’’ PMT

(2016)

2x water shield Resis+ve plate chamber Water shield LS shield 2x plas+c scin+llator strips

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SLIDE 8

Daya Bay Timeline

  • Ini+ally Daya Bay operated with

6 an+neutrino detectors (ADs) for 217 days

  • During summer 2012 shutdown,

remaining 2 ADs were installed

8

Installation of ADs

12 Automatic Calibration Units (ACUs) Antineutrino Detector(AD) Water Cerenkov Detector RPC

6-AD 8-AD Data Taking 2013 2012 2014 2015

621-day data Sterile results

2016

1230-day data 3ν results 217 days

EH3

Neutrino 2014 result Neutrino 2016 result

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SLIDE 9

9

Analysis results

  • With 1230 days’ data:
  • Neutrino oscillation analysis
  • Most precise sin22θ13 and |Δm2

ee|

  • To be on arXiv soon
  • With 621 days’ data:
  • Reactor νe flux and spectrum
  • To be on arXiv soon
  • Independent measurement of sin22θ13
  • Via neutron capture on Hydrogen
  • Phys. Rev. D 93, 072011 (2016)
  • Search for a light sterile neutrino
  • To be on arXiv soon

8

EH1: Daya Bay Near Hall EH2: LingAo Near Hall EH3: Far Hall 621 days 1230 days

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SLIDE 10

IBD selec+on flowchart

10

Inverse Beta-Decay (IBD) IBD selec+on

  • 1. Prompt signal
  • 2. Delayed signal (~8MeV)
  • 3. Separa+on in +me ~30 μs

Flasher Cut

  • 4. Remove PMT “flashing”

background Mul+plicity Cut

  • 5. Remove “ambiguous”

signal sets with greater than 2 mul+plicity Muon Veto

  • 6. Ignore events close in

+me aoer muon hits detector to reduce cosmogenic backgrounds Mul+plicity

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SLIDE 11

IBD selec+on (Energy)

  • 1. 0.7 MeV ≤ Eprompt ≤ 12 MeV
  • 2. 6 MeV ≤ Edelayed ≤ 12 MeV

1 10

2

10

3

10

4

10

5

10

Delayed energy (MeV)

2 4 6 8 10 12 14 16

Prompt energy (MeV)

2 4 6 8 10 12 14 16

0.7 MeV cut for Eprompt

  • Assuming 2% rela+ve energy scale between detectors (See Energy Calibra+on talk)
  • 0.7 MeV cutoff leads to 0.01% rela+ve uncertainty in IBD efficiency

IBD Energy Cuts 6 MeV cut for Edelayed

  • 6 MeV cutoff leads to 0.08% rela+ve uncertainty in IBD efficiency

11

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SLIDE 12

IBD selec+on (Time)

  • 3. 1 μs ≤ Δt ≤ 200 μs

IBD Time Cuts

AD1 AD2 AD3 AD8 AD4 AD5 AD6 AD7

s) µ time(

28 28.5 29 IBD neutrons

AD1 AD2 AD3 AD8 AD4 AD5 AD6 AD7

Neutron capture

28 28.5 29 AmC neutrons

Detector

AD1 AD2 AD3 AD8 AD4 AD5 AD6 AD7

28 28.5 29 Spallation neutrons

20 40 60 80 100 120 140 160 180 200

Events 1 10

2

10

3

10

4

10

5

10

EH1-AD1 EH3-AD4 EH1-AD2 EH3-AD5 EH2-AD3 EH3-AD6 EH2-AD8 EH3-AD7

20 40 60 80 100 120 140 160 180 200

<AD> AD1 0.95 1 1.05

20 40 60 80 100 120 140 160 180 200

<AD> AD2 0.95 1 1.05

20 40 60 80 100 120 140 160 180 200

<AD> AD3 0.95 1 1.05

20 40 60 80 100 120 140 160 180 200

<AD> AD8 0.95 1 1.05

20 40 60 80 100 120 140 160 180 200

<AD> AD4 0.95 1 1.05

20 40 60 80 100 120 140 160 180 200

<AD> AD5 0.95 1 1.05

20 40 60 80 100 120 140 160 180 200

<AD> AD6 0.95 1 1.05

s) µ IBD prompt-delayed signal time internal ( 20 40 60 80 100 120 140 160 180 200

<AD> AD7 0.95 1 1.05

1 μs cut for Δt

  • Less than 1 μs rejected because within a

single trigger readout of the detector

12

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SLIDE 13

Flasher cut

  • Rejec+on of PMT light emission background events
  • 4. Reject fID ≥ 0

Flasher Cuts

0.10 0.06 0.06 0.22 0.12 0.28 0.26 0.21 0.10 0.11 0.17 0.11 0.08 0.08 0.06 0.06 0.04 0.23 0.15 0.10 0.06 0.05 0.08 0.15 0.07 0.04 0.04 0.08 0.21 0.87 0.75 0.28 0.21 0.23 0.15 0.22 0.11 0.22 0.12 0.19 0.10 0.12 0.19 0.22 0.08 0.12 0.17 0.23 0.16 0.07 0.09 0.27 0.66 2.97 5.05 0.36 0.31 0.26 0.16 0.14 0.11 0.11 0.09 0.33 0.11 0.22 0.31 0.50 0.13 0.13 0.19 0.29 0.11 0.04 0.18 0.39 0.54 1.19 0.71 1.26 0.87 0.42 0.16 0.15 0.24 0.11 0.19 0.24 0.25 0.42 2.79 0.70 0.24 0.22 0.31 0.17 0.10 0.13 0.16 0.21 0.67 0.34 0.75 0.53 0.71 0.46 0.28 0.09 0.17 0.09 0.25 0.17 0.25 0.86 42.07 0.91 0.36 0.32 0.28 0.33 0.13 0.13 0.21 0.14 0.55 0.32 0.72 0.71 0.58 0.40 0.21 0.21 0.04 0.17 0.16 0.18 0.39 0.44 0.78 0.43 0.44 0.20 0.16 0.07 0.06 0.10 0.09 0.19 0.30 0.24 0.96 0.64 0.25 0.18 0.12 0.13 0.15 0.09 0.16 0.14 0.03 0.29 0.34 0.15 0.09 0.18 0.22 0.13 0.13 0.10 0.19 0.23 0.20 0.18 0.32 0.25 0.20 0.18 0.13 0.14 0.19 0.15 0.09 0.10 0.05 0.09 0.11 0.14 0.07 0.11 0.14 0.08

Column 2 4 6 8 10 12 14 16 18 20 22 24 Ring 1 2 3 4 5 6 7 8 9

1 −

10 1 10 Quadrant 1 Quadrant 2 Quadrant 3 Quadrant 4

fmax = Qmax / Qtotal fquad = Q3 / (Q2 +Q4)

ID

f

2 − 1.5 − 1 − 0.5 − 0.5 1 1.5 2

Arbitrary Units

4 −

10

3 −

10

2 −

10

1 −

10 1 10

AD1 AD2 AD3 AD8 AD4 AD5 AD6 AD7

Flasher tagged PMT hitmap for flasher event

13

See Flasher Talk (Zhe)

slide-14
SLIDE 14

Mul+plicity Veto

  • Want clean 2 signals

(prompt + delayed) events

  • Avoid ambiguity by

rejec+ng mul+plicity > 2

  • 5. No signal > 0.7 MeV 200 μs before prompt
  • 6. No signal > 0.7 MeV 200 μs aoer delayed

Mul=plicity Veto

Method A

  • 5. Only one signal (0.7,12) MeV 400 μs before delayed
  • 6. No signal (6,12) MeV 200 μs aoer delayed

Mul=plicity Veto

Method B

14

Fixed 600 μs +me window 200 μs buffer around IBD candidate pair

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SLIDE 15

Muon Veto

  • Avoid events close in +me to muon striking detectors to

minimize cosmogenic backgrounds (9Li, fast-neutrons)

  • Gd-doped

liquid scintillator LS Mineral Oil 192 8’’ PMT

  • Nucl. Instrum. Meth. A 811, 133 (2016)
  • Nucl. Instrum. Meth. A 773, 8 (2015)

192 8’’ PMT

(2016)

  • 7. If NHIT > 12 in either OWS or IWS,

veto (-2,600) μs

Muon hiTng waterpool Muon hiTng AD

Method A Method B

  • 8. Low energy muon Veto 1ms aoer

>20 MeV Veto 1.4ms aoer >3,000 p.e. (~18 MeV)

  • 9. High energy muon Veto 1s aoer

>2.5 GeV Veto 0.4s aoer >30,000 p.e. (~1.8 GeV)

15

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SLIDE 16

Summary of IBD selec+on Cuts

1 2 3 4 5 6 7 8

IBD rate (/day) 200 400 600 800

Selection A Selection B

AD1 AD2 AD3 AD8 AD4 AD5 AD6 AD7

B/A 0.995 1 1.005

Comparison of IBD rate using methods A and B

Ra+o differs by ~0.2%, difference in absolute selec+on efficiency

16

Flasher cuts IBD selec+on Mul+plicity veto Muon veto

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SLIDE 17

Evolu+on of event selec+on (EH1-AD1)

17

Cut A: AD trigger event Cut B: + Flasher Cut Cut C: + “loose” WP muon (200μs) Cut D: + IBD (prompt/delayed) Cut E: + WP+AD muon cut