RENO for Neutrino Mixing Angle q13 (“Neutrinos in Cosmology, in Astro-, Particle- and Nuclear Physics” Sep. 16-24, 2009, Erice/Sicily, Italy) Soo-Bong Kim Seoul National Univ.

New Reactor Neutrino q13 Experiment CHOOZ : Rosc = 1.01 ± 2.8% (stat) ± 2.7% (syst) → Obtain ~1% precision !!! Larger statistics - More powerful reactors (multi-core) - Larger detection volume - Longer exposure arXiv:0905.3549v2, Fogli et. al. Hint of q13 >0 from different data sets and combinations : 1s range Smaller experimental errors - Identical multi detectors Lower background - Improved detector design - Increased overburden

Detection of Reactor Neutrinos data from CHOOZ hep-ex/0301017v1 (1) 0.7<Eprompot <9MeV (2) 5<Edelayed <11MeV (3) 1μs<ΔT <200μs e+ energy n capture energy

RENO Collaboration (11 institutions and 40 physicists) Chonnam National University Dongshin University Gyeongsang National University Kyungpook National University Pusan National University Sejong University Seoul National University Sungkyunkwan University Seokyeong University Institute of Nuclear Research RAS (Russia) Institute of Physical Chemistry and Electrochemistry RAS (Russia) +++ http://neutrino.snu.ac.kr/RENO

Comparison of Reactor Neutrino Experiments Location Thermal Power (GW) Distances Near/Far (m) Depth (mwe) Target Mass (tons) Double-CHOOZ France 8.7 280/1050 60/300 10/10 RENO Korea 17.3 290/1380 120/450 16/16 Daya Bay China 11.6 360(500)/1985(1613) 260/910 402/80

Schematic Setup of RENO at YongGwang

Google Satellite View of YongGwang Site

Schematic View of Underground Facility 70m high 200m high 1,380m 290m Far Detector Near Detector Reactors

RENO Detector 421(354+61) 10” PMTs total ~460 tons Inner Diameter (cm) Inner Height (cm) Filled with Mass (tons) Target Vessel 280 320 Gd(0.1%) + LS 16.1 Gamma catcher 400 440 LS 28.5 Buffer tank 540 580 Mineral oil 64.4 Veto tank 840 880 water 352.6 421(354+61) 10” PMTs total ~460 tons

Schedule

Summary of Construction Status 03~10, 2007 : Geological survey and tunnel design are completed. 07~11, 2008 : Construction of both near and far tunnels are completed. 12, 2008 ~ 03, 2009 : Veto tanks and peripheral facilities (electricity, air circulation, drainage, network, etc.) are completed. 10, 2008 : A mockup detector (~1/10 in volume) was built and is tested out. 11, 2008 : SK new electronics were adopted and ready. Steel/acrylic containers and mechanical structures are under installation and will be completed until Nov. 2009. PMT installation is expected to start from Dec. 2009. Both near and far detectors are expected to be ready for data-taking in mid 2010.

(2007.3~2007.8) Rock quality map Near detector site: tunnel length : 110m overburden height : 46.1m Far detector site: tunnel length : 272m overburden height : 168.1m

Detectorvertical hall Design of Tunnels (2007.9~2007.11) Wing tunnel(L) Access tunnel Experimental hall Wing tunnel(C) Detector Experimental hall Access tunnel Wing tunnel(C) Detectorvertical hall

Near & far tunnels are completed (2008.6~2009.3) by Daewoo Eng. Co. Korea

Detector vertical halls are ready (2008.12~2009.2)

Buffer steel tanks are installed (2009.6~2009.9) by NIVAK Co. Korea

Acrylic vessels will be ready in Nov. 2009 Bending acrylic plates (2009.7~2009.11) by KOATECH Co. Korea Target Gamma catcher Bending acrylic plates A half of target

Mockup Detector ~1/10 of RENO in volume Target + Gamma Catcher Acrylic Containers (PMMA: Polymethyl Methacrylate or Plexiglass) Target Diameter 61 cm Height 60 cm Gamma Catcher 120 cm Buffer 220 cm Buffer Stainless Steel Tank ~1/10 of RENO in volume

Mockup Detector Assembly

Energy Calibration of Mockup Detector 252Cf 60Co 137Cs 60Co 137Cs

Electronics Use SK new electronics (all hardwares are ready) Conceptual design of the system

Gd Loaded Liquid Scintillator Aromatic Solvent & Flour CnH2n+1-C6H5 (n=10~14) Recipe of Liquid Scintillator Aromatic Solvent & Flour WLS Gd-compound LAB PPO + Bis-MSB 0.1% Gd+TMHA (trimethylhexanoic acid) High Light Yield : not likely Mineral oil(MO) replace MO and even Pseudocume(PC) Good transparency (better than PC) High Flash point : 147oC (PC : 48oC) Environmentally friendly (PC : toxic) Components well known (MO : not well known) Domestically available: Isu Chemical Ltd. (이수화학) 0.1% Gd compounds with CBX (Carboxylic acids; R-COOH) - CBX : MVA (2-methylvaleric acid), TMHA (trimethylhexanoic acid)

RENO Analysis Control Raw/MC Data Production Modules Reconstruction User Analysis ntuples RACFrameWork default modules data input and output, database access for run configuration and calibration Has talk-to function for changing input parameters without recompiling Addition of modules by user Modules can be set as filter module for selecting events Easy to use and build in RENO software environment

Reconstruction : vertex & energy Reconstructed vertex:  ~8cm at the center of the detector y 4 MeV (KE) e+ |y| sy (mm) Evis (MeV) Energy response and resolution: visible energy PMT coverage, resolution ~210 photoelectrons per MeV 1 MeV (KE) e+

Reconstruction of Cosmic Muons A B C D Veto (OD) Buffer (ID) pulse height time OD PMTs ID PMTs target buffer g-catcher

RENO Event Display

Calculation of Background Rates due to Radioactivity Concentration 40K (ppb) Concentration 232Th (ppb) Concentration 238U (ppb) 40K [Hz] 232Th [Hz] 238U [Hz] Total [Hz] Rock 4.33(ppm) 7.58(ppm) 2.32(ppm) 1.06 7.14 0.99 9.2 LS in Target 0.010 0.018 0.014 9.00 1.63 3.67 14.3 Target Contatiner 0.008 0.207 0.168 0.08 0.24 0.63 1.0 LS in Gamma Catcher 15.18 2.27 5.27 22.7 Gamma Catcher Container 0.07 0.17 0.9 LS in Buffer 0.020 0.005 0.77 0.16 0.14 1.1 Buffer Tank 0.06 0.03 0.10 0.20 0.3 PMT 13.6 208.5 49.4 2.50 5.23 2.99 10.7 Total ~60.2

Systematic Uncertainty Goals Systematic Source CHOOZ (%) RENO (%) Reactor related absolute normalization Reactor antineutrino flux and cross section 1.9 < 0.1 Reactor power 0.7 0.2 Energy released per fission 0.6 Number of protons in target H/C ratio 0.8 Target mass 0.3 Detector Efficiency Positron energy 0.1 Positron geode distance 0.0 Neutron capture (H/Gd ratio) 1.0 Capture energy containment 0.4 Neutron geode distance Neutron delay Positron-neutron distance Neutron multiplicity 0.5 0.05 combined 2.7 < 0.5

Expected Number of Neutrino Events at RENO 2.73 GW per reactor ⅹ 6 reactors 1.21x1030 free protons per targets (16 tons) Near : 1,280/day, 468,000/year Far : 114/day, 41,600/year 3 years of data taking with 70% efficiency Near : 9.83x105 ≈ 106 (0.1% error) Far : 8.74x104 ≈ 105 (0.3% error)

RENO Expected Sensitivity 90% CL Limits Discovery Potential” (3s)

RENO Expected Sensitivity New!! (full analysis) 10x better sensitivity than current limit

GLoBES group workshop@Heidelberg – Mention’s talk SK Dm2

Status Report of RENO RENO is suitable for measuring q13 (sin2(2q13) > 0.02) Geological survey and design of access tunnels & detector cavities are completed → Civil construction was finished in February, 2009. Buffer steel containers are installed. RENO is under installation phase. Data –taking is expected to start in mid 2010. International collaborators are being invited.