Measurement of the Electron Antineutrino Oscillation with 1958 Days of Operation at Daya Bay.

D Adey,L Guo,L Mora Lepin,M Qi,S Zeng,Y Liu,J Lee,Q Wu,M Dolgareva,J Zhao,K Whisnant,W.-H Tse,T Wise,N Raper,A Olshevskiy,H Gong,D Taychenachev,R Zhang,G Hussain,Z Wang,S Li,D Jones,D Naumov,S Patton,H Liang,C Zhang,B Viren,F Li,C Marshall,T Hu,S Blyth,M He,A Chukanov,V Pec,S Kohn,V Vorobel,W Tang,T Xue,M Bishai,M Ye,R Leitner,S Hans,D Cao,E Worcester,M Gonchar,L Pinsky,L Lebanowski,J Wang,C Li,C Lu,J Park,X Wang,B Roskovec,J Napolitano,R Rosero,S Lin,W Wang,X Qian,Y Chen,A Higuera,H Steiner,L Littenberg,M Yeh,J S Lu ,Yun Hsuan Chang ,Jie Ren ,X B ,J H C Lee ,S M Chen ,H L Li ,C White ,A B Balantekin ,H S Chen ,C H Wang ,X N Li ,X Y ,W D Li ,C C Zhang ,Yongbo Huang ,C W Loh ,J P Ochoa-Ricoux ,Z B Li ,H L Zhuang ,Baobiao Yue ,Zhou Li ,Y H Liu ,Ziyi Guo ,J K C Leung ,Jing Xu ,K M Heeger ,Y K Heng ,J F Chang ,R Hackenburg ,K B Luk ,Y X Chen ,Q M Zhang ,Rui Qiu ,Q J Li ,Y F Wang ,Mingkan Wang ,Y Hsiung ,Liang Zhan ,S C Li ,Ruiting Lei ,Changgen Yang ,M S Yang ,S H Kettell ,M V Diwan ,R A Johnson ,J W Zhang ,Yayun Ding ,C E Tull ,K L Jen ,M T Yang ,Haibo Yang ,Xin-Heng Guo ,B R Littlejohn ,W Wu ,C J Lin ,Z M Wang ,Zezhong Yu ,Y Q ,Jun Hu ,Hsiao-Ru Pan ,Jie Cheng ,Haoqi Lu ,J L Liu ,Patrick Huber ,L Wen ,Yuhang Guo ,J C Peng ,X T Zhang ,Z J Zhang ,Z Y Zhang ,Y M Zhang ,Jiajie Ling ,F Z Qi ,J P Cummings ,Bei-Zhen Hu ,F Y Zhang ,M Krämer ,Guanghua Gong ,X T Huang ,Y F Li ,Ben Young ,Zheng Peng ,M C Chu ,Zhaokan Cheng ,Kang Li ,F S Deng ,R G Wang ,Y Y Zhang ,X Ji ,Sun Wong ,X Q Li ,Kirk T Mcdonald ,H R Band ,X C Ruan ,R D Mckeown ,Hongzhao Yu ,Z J Hu ,T Langford ,D E Jaffe ,Konstantin Treskov ,Wenju Huo ,L W Koerner ,Zhi-Zhong Xing ,D A Martínez Caicedo ,Y M Malyshkin ,Y L Chan ,N Y Wang ,Lei Yang ,S J Li ,G F Cao ,Yifan Yang ,J C Liu ,Y X Zhang ,H Wei ,H L H Wong ,X L Ji ,X F Zhang ,J M Link ,C S J Pun ,Y C Lin ,Э Наумова ,Jun Cao ,Fengpeng An ,Jian Sun ,Dongmei Xia ,Hanxiong Huang ,W Gu ,H H Zhang ,W R Edwards ,J J Cherwinka ,Z P Zhang ,G L Lin ,D A Dwyer ,Lianghong Wei ,I.v Mitchell ,J H Zou

doi:10.1103/physrevlett.121.241805

Abstract

We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4million reactor ν[over ¯]_{e} inverse β decay candidates observed over 1958days of data collection. The installation of a flash analog-to-digital converter readout system and a special calibration campaign using different source enclosures reduce uncertainties in the absolute energy calibration to less than 0.5% for visible energies larger than 2MeV. The uncertainty in the cosmogenic ^{9}Li and ^{8}He background is reduced from 45% to 30% in the near detectors. A detailed investigation of the spent nuclear fuel history improves its uncertainty from 100% to 30%. Analysis of the relative ν[over ¯]_{e} rates and energy spectra among detectors yields sin^{2}2θ_{13}=0.0856±0.0029 and Δm_{32}^{2}=(2.471_{-0.070}^{+0.068})×10^{-3} eV^{2} assuming the normal hierarchy, and Δm_{32}^{2}=-(2.575_{-0.070}^{+0.068})×10^{-3} eV^{2} assuming the inverted hierarchy.

Highlights

We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4 million reactor νe inverse β decay candidates observed over 1958 days of data collection
This Letter presents a measurement of these two parameters with a data set acquired in 1958 days of stable operation, and with several improvements to the analysis when compared with previous measurements
The inner acrylic vessel is filled with 20-t 0.1% gadolinium-doped liquid scintillator (Gd LS), which serves as the primary νe target

Summary

Published by the American Physical Society

The Daya Bay experiment previously reported the observation of a nonzero value of sin2 2θ13 via the disappearance of reactor antineutrinos over ∼kilometer distances [1], and a measurement of the effective mass-squared difference Δm2ee via the distortion of the νe energy spectrum [6]. Both of these measurements based on 1230 days of operation are described in detail in Ref. The readout system underestimates the charge of the PMT signals when they overlap in time due to the AC coupling of the front end electronics This results in a nonlinear response of the charge over the entire detector at the ∼10% level in the energy region of interest.

Reconstructed True prompt energy

The detection efficiencies are described in detail in

Findings

Far site data