Youngdo Oh Pohang University of science and Technology Current Status of RENO NOW2008 (Conca Specchiulla, Italy)

RENO Collaboration  Chonnam National University  Chonpook National University  Dongshin University  Gyeongsang National University  Kyungpook National University  Pusan National University  Sejong University  Seoul National University  Sungkyunkwan University  Pohang University of Science and Technology  Institute of Nuclear Research RAS (Russia)  Institute of Physical Chemistry and Electrochemistry RAS (Russia) institutes, 39 members (Reactor Experiment for Neutrino Oscillation)

 Located in the west coast of southern part of Korea  ~400km from Seoul  6 reactors are lined up in roughly equal distances and span ~1.3 km  Total average thermal output ~16.4GW th (2 nd largest in the world) Yong Gwang Nucleat Power Plant

Schematic Setup of RENO at YongGwang

Google Satellite View of YongGwang Site

Schematic View of Underground Facility Experimental Hall Access Tunnel Detector (4m high ☓ 4m wide) Tunnel Detector

Schedule Activities Detector Design & Specification Geological Survey & Tunnel Design Detector Construction Excavation & Underground Facility Construction Detector Commissioning We are here

Comparison of Reactor Neutrino Experiments ExperimentsLocation Thermal Power (GW) Distances Near/Far (m) Depth Near/Far (mwe) Target Mass (tons) Double-CHOOZFrance8.7280/105060/30010/10 RENOKorea / /45015/15 Daya BayChina (500)/1985(1613)260/  2/80

Rock sampling (DaeWoo Engineering Co.) Rock samples from boring For chemical composition, density, radioactivity

Near detector site: - tunnel length : 110m - height : 46.1m Far detector site: - tunnel length : 272m - height : 168.1m Rock quality map

Tunnel Design

연속체 안정성 검토 터널변위 및 응력해석 불연속체 안정성 검토 터널변위 및 응력해석 키블럭 안정성 검토 암반 블록파괴 검토 접속부 안정성 검토확폭 및 수직터널 안정성 검토 터널변위 및 응력해석 콘크리트 구조 검토 구조물 안정성 검토 접속부변위 및 응력해석 Stress analysis for tunnel design

Tunnel Construction is on going …. Near tunnel Far tunnel On-site office Power Plant 50m From entrance

Inner Diameter (cm) vesselInner Height (cm) Filled withMass (tons) Target Vessel280Acryl320Gd(0.1%) + LS15.4 Gamma catcher400Acryl440LS27.5 Buffer tank540Stainless steel580Mineral oil(LAB)59.2 Veto tank840Steel880water354.7 total ~450 tons Veto Buffer Target  -catcher  Four concentric cylindrical parts  Identical detectors for near and far  Target and gamma catcher are filled with liquid scintillator  aiming at detecting inverse beta decay  inch PMTs on the surface of buffer inch PMTs on the VETO RENO Detector

Target : - Gd + LS Gamma catcher : - LS Buffer : - Non scintillating oil Veto : - Water Shielding : - Steel Inverse beta decay in RENO Detector p ν e e + γ (0.511MeV) n Gd γ γ γ γ 30μs prompt signal Delayed signal E  ~ 8MeV 

CAD views of RENO Detector

Detector Design with MC Simulation  Detector performance study & Detector optimization with MC : - Gamma catcher size - Buffer size - photo-sensor coverage (numbers of PMTs) - neutron tagging efficiency as a function of Gd concentration  Systematic uncertainty & sensitivity study  Reconstruction(vertex position & energy) program written  Background estimation  RENO-specific MC simulation based on GLG4sim/Geant4  Detailed detector design and drawings are completed

Systematic Errors Systematic SourceCHOOZ (%)RENO (%) Reactor related absolute normalization Reactor antineutrino flux and cross section 1.9< 0.1 Reactor power Energy released per fission0.6< 0.1 Number of protons in target H/C ratio Target mass0.3< 0.1 Detector Efficiency Positron energy Positron geode distance0.1- Neutron capture (H/Gd ratio)1.0< 0.1 Capture energy containment Neutron geode distance0.1- Neutron delay Positron-neutron distance0.3- Neutron multiplicity combined2.7< 0.5 Not final, under study

RENO Expected Sensitivity

GLoBES group – Mention’s talk SK  m 2

 R&D with the Russian INR/IPCE group (Gd powder supply)  Recipe with various mixture: performance ( light yield, transmission & attenuation lengths ), availability, cost, etc.  Design of purification system & flow meter  Long-term stability test  Reaction with acrylic  R&D on LAB  General Elements of Liquid Scintillator : AromaticOilFlourWLSGd-compound PC(Pseudocumene), PXE, LAB Mineral oil, Dodecane, Tetrdecane, LAB PPO, BPOBis-MSB, POPOP 0.1% Gd compounds with CBX or BDK  PC(20%) + Dodecane(80%) + PPO with bis-MSB or BPO  0.1% Gd compounds with CBX or BDK R&D : Liquid scintillator (1)

Chemical elements H:C M.W. (g/mol) Density (g/ml) Boiling Point Flash Point ℃ comments decane C10H cps Domestically available dodecane C12H Expensive tetradecane C14H PC(=TMB) C9H (0.876)16948 Toxic Low FP LAB C6H5 (CnH2n+1) cps R&D in progress Nontoxic Inexpensive PXE Less toxic Supply limited MO CnH2n+2, n=10-44 ~0.8 ~ Uncertainty in no. of protons PC20dod PXE20dod >80 PC20MO PC40MO R&D : Liquid scintillator (2)

R&D with LAB instead of PC/PXE + Dodecane Light yield measurement C n H 2n+1 -C 6 H 5 (n=10~14) High Light Yield Good transparency (better than PC) High Flash point : 147 o C (PC : 48 o C) Environmentally friendly (PC : toxic) Components well known (MO : not well known) Domestically available: Isu Chemical Ltd. R&D : Liquid scintillator (3)

Measurement of LAB Components with GC-MS C 16 H 26 C 17 H 28 C 18 H 30 C 19 H % 27.63% 34.97% 30.23% LAB : (C 6 H 5 )C N H 2N+1 # of H [m -3 ] = x H/C = 1.66 R&D : Liquid scintillator (4) N=10 N=11 N=12 N=13

R&D : Prototype Detector ( 2007 ) The prototype detector was bulit  to test properties liquid scintillator  to validate the Monte Carlo Simulation model based on Geant4

Prototype Detector Assembly Acrylic vesselsInner acrylic vessel Nitrogen flushing of LS Mounting PMTs Filling with liquid scintillator assembled prototype

R&D : Mockup Detector ( 1 )  By building mockup detector, we will answer the technical questions for final design of main detector.  ~40% scale to the main detector in size and inch PMTs  To test  Fabrication in Sepember 2008  Data taking from October 2008, for next 6 months - long tem stability and light transmittance of acrylic tank - source and light calibration - PMT performance in mineral oil - liquid handling system - daq and data manipulation diameter height Target 60cm 60cm Gamma catcher 120cm 120cm Buffer 220cm 220cm

R&D : Mockup Detector ( 2 ) - PMT installation is done last week. - DAQ and HV system ready - Calibration system (this week) - LS filling from next week - Data taking from October for 6 months

R&D : Mockup Detector ( 3 ) Source and light calibration system : 137 Cs, 60 Co, 22 Na, 252 Cf, LED DAQ for mockup – 400MHz FADC Liquid handling system Pulse generator LED Trigger Pulse generator LED Trigger Pulse generator LED Diffuse ball LED Trigger

R&D : Mockup Detector ( 4 ) Energy response of the mockup to the 137 Cs(left) 60 Co(right) at the center of the detector Energy linearity (left) and energy resolution(right) for positron  Geant4 Monte Calro Simulation

Status Report of RENO  RENO is suitable for measuring  13 (sin 2 (2  13 ) > 0.02)  RENO is under construction phase.  Geological survey and design of access tunnels & detector cavities are completed → Excavation started  International collaborators are being invited.  Mockup detector will operate soon.  Data –taking is expected to start in early 2010.

Back up slide

Principle of Neutrino Detection  Use inverse beta decay (v e + p e + + n) reaction process  Prompt part: subsequent annihilation of the positron to two 0.511MeV   Delayed part: neutron is captured ~200  s w/o Gd ~  s w Gd Gd has largest n absorption cross section & emits high energy   Signal from neutron capture ~2.2MeV w/o Gd ~ 8MeV w Gd  Measure prompt signal & delayed signal  “Delayed coincidence” reduces backgrounds drastically

Gamma catcher thickness = 20cmGamma catcher thickness = 90cm MeV Study on  -catcher size Daya Bay 45cm: 92% Chooz 70cm: (94.6+/-0.4)% RENO 70cm: (94.28+/-0.54)% 60cm: (92.98+/-0.56)% Gd capture H capture

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

target buffer  -catcher Reconstruction of Cosmic Muons ~140cm ~40cm ~120cm A B C D Veto (OD) Buffer (ID) pulse height time OD PMTs ID PMTs

J μ [cm -2 s -1 ] [GeV] Far 250 m2.9× m8.5× Near70 m5.5× Muon intensity at the sea level using modified Gaisser parametrization + MUSIC or Geant4 (the code for propagating muon through rock) Calculation of Muon Rate at the RENO Underground

Calculation of  Background at the RENO Underground    rate from rock [Hz] Double CHOOZ Daya BayRENO Rock composition (K) 1.6 ppm (U) 2.00 ppm (Th) 5.0 ppm (K) 5 ppm (U) 10 ppm (Th) 30 ppm (K) 4.0 ppm (U) 4.8+/-1.8 ppm (Th) 6.0+/-2.2 ppm * Sample from Chongpyung. Detector DxH Size [cm] 230x246 (10.3 m3) 320x320280x320 Shelding17 cm Steel2.5 m Water m Oil 2.5 m Water Rates (K) [Hz] (U) (Th) 0.86 ~ (E  >1 MeV) (E  >0.5 MeV) Total rate~2.73 Hz3.5 Hz2.5 Hz

03~08, 2006 : Project description to local government, residents, and NGO’s (endorsed by local government) 03, 2007 : Agreement between KHNP and SNU 03~10, 2007 : Geological survey and tunnel design are completed. 12, 2007 : Public hearing for YG residents 01, 2008 : Safety regulation established and accepted by the atomic energy department of MOST 05~11, 2008 : Tunnel construction Efforts for On-site Facility