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

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 Ling Ao II NPP 2 2.9 GW th 2 2.9 GW th Entrance to Daya Bay experiment tunnels Spectral Measurement of An+neutrino 16/10/16 2 Oscilla+on at Daya Bay

Experiment Layout Far hall measures oscilla=on Far Hall (EH3) Ling Ao near Tunnel Hall (EH2) Water Hall Construction Ling Ao II tunnel reactors LS Two near halls Ling Ao Hall constrain reactor flux reactors Entrance Daya Bay Near Hall (EH1) Reactor power Daya Bay reactors 6 × 2.9 GW th 3

Daya Bay Advantages Baseline Op+miza+on • Detector loca+ons op+mized to known parameter space of |Δm 2 ee | • Far site maximizes term dependent on sin 2 2θ 13 Daya Bay RENO Double Chooz Go strong, big and deep! Reactor [GW th ] 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 4

Daya Bay Detectors • An+neutrino Detector (AD) Muon Veto System Auto calibration units (IWS) (OWS) Two op+cally 192 8’’ PMT separated water Cherenkov system Mineral Gd-doped LS Oil liquid scintillator 5 Nucl. Instrum. Meth. A 811, 133 (2016) Nucl. Instrum. Meth. A 773, 8 (2015)

Quick Comparison of An+neutrino Detector • 192 8’’ PMT Mineral Gd-doped LS Oil liquid scintillator Nucl. Instrum. Meth. A 811, 133 (2016) 390 10-inch PMT 192 8-inch PMT 354 10-inch PMT 2x reflectors on top+boiom PXE/Dodecane based LS LAB based LS LAB based LS 6

Quick Comparison of Muon Veto System • 192 8’’ PMT Nucl. Instrum. Meth. A 773, 8 (2015) (2016) LS shield Water shield 2x water shield 2x plas+c scin+llator strips Resis+ve plate chamber 7

Daya Bay Timeline Installation of ADs 217 days 8-AD Data Taking 6-AD 2015 2016 2012 2013 2014 621-day data Sterile results Neutrino 2014 result 1230-day data 3ν results Neutrino 2016 result EH3 RPC • Ini+ally Daya Bay operated with 6 an+neutrino detectors (ADs) for 217 days Automatic Calibration Units (ACUs) • During summer 2012 shutdown, remaining 2 ADs were installed Water Cerenkov Detector 8 Antineutrino Detector(AD) 12

EH1: Daya Bay Near Hall Analysis results • With 1230 days’ data: • Neutrino oscillation analysis EH2: LingAo Near Hall • Most precise sin 2 2 θ 13 and | Δ m 2 ee | • To be on arXiv soon • With 621 days’ data: • Reactor ν e flux and spectrum EH3: Far Hall • To be on arXiv soon • Independent measurement of sin 2 2 θ 13 • Via neutron capture on Hydrogen • Phys. Rev. D 93, 072011 (2016) • Search for a light sterile neutrino • To be on arXiv soon 621 days 8 9 1230 days

IBD selec+on flowchart 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 Mul+plicity Muon Veto 6. Ignore events close in +me aoer muon hits detector to reduce cosmogenic backgrounds 10

IBD selec+on (Energy) 16 IBD Energy Cuts 5 14 10 1. 0.7 MeV ≤ E prompt ≤ 12 MeV 12 4 10 Prompt energy (MeV) 2. 6 MeV ≤ E delayed ≤ 12 MeV 10 3 10 8 6 2 10 4 10 2 0 1 0.7 MeV cut for E prompt 0 2 4 6 8 10 12 14 16 Delayed energy (MeV) 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 • 6 MeV cut for E delayed 6 MeV cutoff leads to 0.08% rela+ve uncertainty in IBD efficiency • 11

IBD selec+on (Time) 5 10 IBD Time Cuts 4 10 3. 1 μs ≤ Δt ≤ 200 μs 3 10 Events 2 10 1 μs cut for Δt EH1-AD1 EH3-AD4 EH1-AD2 EH3-AD5 Less than 1 μs rejected because within a • 10 EH2-AD3 EH3-AD6 single trigger readout of the detector EH2-AD8 EH3-AD7 1 s) <AD> 1.05 AD1 0 20 40 60 80 100 120 140 160 180 200 1 29 IBD neutrons 0.95 <AD> 1.05 0 20 40 60 80 100 120 140 160 180 200 AD2 1 28.5 0.95 µ <AD> time( 1.05 0 20 40 60 80 100 120 140 160 180 200 AD3 1 28 0.95 <AD> 1.05 0 20 40 60 80 100 120 140 160 180 200 Neutron capture AD8 AD1 AD2 AD3 AD8 AD4 AD5 AD6 AD7 29 1 AmC neutrons 0.95 <AD> 1.05 0 20 40 60 80 100 120 140 160 180 200 AD4 1 28.5 0.95 <AD> 1.05 0 20 40 60 80 100 120 140 160 180 200 AD5 1 28 0.95 <AD> 1.05 AD1 AD2 AD3 AD8 AD4 AD5 AD6 AD7 0 20 40 60 80 100 120 140 160 180 200 AD6 29 1 0.95 <AD> 1.05 0 20 40 60 80 100 120 140 160 180 200 AD7 28.5 1 0.95 Spallation neutrons 0 20 40 60 80 100 120 140 160 180 200 12 28 IBD prompt-delayed signal time internal ( s) µ AD1 AD2 AD3 AD8 AD4 AD5 AD6 AD7 Detector

Flasher cut See Flasher Talk (Zhe) • Rejec+on of PMT light emission background events Flasher Cuts f max = Q max / Q total 4. Reject f ID ≥ 0 f quad = Q 3 / (Q 2 +Q 4 ) PMT hitmap for flasher event 10 Flasher tagged AD1 Ring 9 AD2 1 8 AD3 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 10 AD8 7 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 Arbitrary Units − 1 10 AD4 6 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 AD5 5 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 AD6 − 2 10 1 AD7 4 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 3 3 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 − 10 2 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 1 − 10 − 4 10 1 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 Quadrant 2 Quadrant 3 Quadrant 4 Quadrant 1 0 2 1.5 1 0.5 0 0.5 1 1.5 2 − − − − 0 2 4 6 8 10 12 14 16 18 20 22 24 f 13 ID Column

Mul+plicity Veto • Want clean 2 signals (prompt + delayed) events • Avoid ambiguity by rejec+ng mul+plicity > 2 Method A 200 μs buffer around IBD candidate pair Mul=plicity Veto 5. No signal > 0.7 MeV 200 μs before prompt 6. No signal > 0.7 MeV 200 μs aoer delayed Method B Fixed 600 μs +me window Mul=plicity Veto 5. Only one signal (0.7,12) MeV 400 μs before delayed 6. No signal (6,12) MeV 200 μs aoer delayed 14

Muon Veto • Avoid events close in +me to muon striking detectors to minimize cosmogenic backgrounds ( 9 Li, fast-neutrons) • Muon hiTng waterpool 192 8’’ PMT 7. If NHIT > 12 in either OWS or IWS, veto (-2,600) μs • Muon hiTng AD (2016) Nucl. Instrum. Meth. A 773, 8 (2015) Method A Method B 192 8’’ PMT 8. Low energy muon Veto 1ms aoer Veto 1.4ms aoer >20 MeV >3,000 p.e. (~18 MeV) Mineral Gd-doped LS Oil liquid scintillator 9. High energy muon Veto 1s aoer Veto 0.4s aoer >30,000 >2.5 GeV p.e. (~1.8 GeV) 15 Nucl. Instrum. Meth. A 811, 133 (2016)

Summary of IBD selec+on Cuts Flasher cuts IBD selec+on Mul+plicity veto Muon veto 800 600 Selection A Comparison of IBD rate IBD rate (/day) Selection B using methods A and B 400 200 1.005 1 2 3 4 5 6 7 8 Ra+o differs by ~0.2%, B/A difference in absolute 1 selec+on efficiency 0.995 AD1 AD2 AD3 AD8 AD4 AD5 AD6 AD7 16

Evolu+on of event selec+on (EH1-AD1) 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 17