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1. install top reflector clean SSV inside test Gd-LS filling probe insert outer AV The Daya Bay Reactor Neutrino Experiment Top reflector calibration system calibration LED PMT Inner acrylic vessel (3m φxH) Liangjian Wen On behalf of the Daya Bay Collaboration Institute of High Energy Physics SSV sits in pit insert Inner AV Outer acrylic vessel (4m φxH) move SSV ● Daya Bay Sensitivity Daya Bay Experiment Is Hunting for θ13 Daya Bay Layout close SSV lid Far: 80 ton 1600m to LA, 1900m to DYB Overburden: 350m Muon rate: 0.04Hz/m2 Stainless steel vessel insert bottom reflector Goal: Sin22 θ13 < 0.01 @ 90% CL in 3 years 5x40ton Gd-LS storage tank 5m Mixing lift PMT ladder Shenzhen Neutrino mixing: where , Bottom reflector LA: 40 ton Baseline: 500m Overburden: 112m Muon rate: 0.73Hz/m2 install ACUs Mineral Oil 55km LS 2x200 ton storage pool Hong Kong Filling Gd-LS N2 room close outer AV lid 2 near + far (3 years) 5m , , , Known: , , Unknown: Value of θ13 is critical for studying CP violation and neutrino mass hierarchy. If Sin22 θ13 <0.01, long baseline experiments with conventional beam have little chance to determine CP violation. arXiv:0907.1896: actual dates differ DYB: 40 ton Baseline: 360m Overburden: 98m Muon rate: 1.2Hz/m2 Determining θ13 by observing electron antineutrino disappearance at reactor. Clean signal, only related to θ13. Relative measurement with near and far detectors. Near Far Daya Bay Detectors Liquid Scintillator Redundancy is a unique feature for this experiment: Identical antineutrino detector modules to reduce errors and cross check. Multiple muon veto: Two zones of Cerenkov detector + RPC at the top. Total efficiency > (99.5  0.25) %. Daya Bay experiment will use 200 ton 0.1% Gd-doped LS and 200 ton normal LS Gd-TMHA + LAB + 3g/L PPO + 15mg/L bis-MSB To ensure IDENTICAL detectors, all Gd-LS will be produced in multiple 4-ton batches and mixed in reservoir on-site. March 2009, a batch of 4 ton Gd-LS was produced successfully. LS hall fluor-LAB 0.1% Gd-LS Gd-LAB Target mass measurement LS hall layout QC room ACU LS production has been started in Oct. 2010 LED Detectors Assembly Dry Run of the first AD pair A full end-to-end test of the fully instrumented Antineutrino Detectors prior to filling them with liquid scintillator. Light from LEDs can be observed as well as Cherenkov light caused by cosmic ray muons passing acrylic. PMT Charge (PE) with LED flashing Double pulse LED to mimic events “e+” LED “n” LED Muon LED Flashing Muon Off-axis LED Consistent performance of AD pair Water Cerenkov Detector Progress RPC Detector Progress Tentative Schedule Waterproof 8” PMTs: Potting and production finished. Water filtration and circulation system ready for installation. Have begun installing Tyvek and PMTs. October 2010, first AD pair complete, Dry-Run tests finished October 2010, Daya Bay Near Hall Occupancy Daya Bay Hall: data taking, Fall 2011 Ling Ao and Far Halls: data taking, Fall 2012 Production and testing for all 1600 RPC s have been completed. More than 85% of RPC modules (2 RPCs x 4 layers) have been assembled and most of them tested. Modules for DYB hall will be ready soon. Support structure for DYB hall has been installed and tested. RPC module Gas system … … 2012 Reach the goal ! The 11th International Workshop on Next generation Nucleon Decay and Neutrino Detectors Toyama, Japan December 13 –16, 2010