jee-seung jang for the reno collaboration, gist international workshop on reno-50 toward neutrino...
TRANSCRIPT
-
Jee-Seung Jang for the RENO collaboration, GISTInternational Workshop on RENO-50 toward Neutrino Mass HierarchSNU, June 13-14, 2013
-
Contents Introduction to RENO (Reactor Experiment of Neutrino Oscillations) Status of RENO Improvements in data analysis & the last results Future plan and Summary
-
q13 Measurement in Reactor Experiment* The Disappearance of Reactor Electron Antineutrino
-
(12 institutions and 40 physicists) Chonbuk National University Chonnam National University Chung-Ang University Dongshin University Gyeongsang National University Kyungpook National University Pusan National University Sejong University Seokyeong University Seoul National University Seoyeong University Sungkyunkwan UniversityRENO Collaboration Total cost : $10M Start of project : 2006The experiment is running with both near & far detectors from Aug. 2011
-
RENO Experimental SetupTotal average thermal output ~16.4 GWth 120 m.w.e.450 m.w.e.
-
Detection of Reactor Antineutrinos* Inverse beta decay (IBD) Neutrino energy measurement
-
354, 10 Inner PMTs ( 14 % surface coverage ) 67, 10 Outer PMTs
ExperimentsLocationThermal Power(GW)Flux Weighted BaselinesNear/Far (m)DepthNear/Far(mwe)Target Mass(tons)Statisticsper year(GWtonyr)Double ChoozFrance8.5[410/1050]120/3008.6/8.673RENOKorea16.7409/1444120/45016/16267Daya BayChina17.4470(576)/1648250/860402/801392
-
Summary of Detector ConstructionTunnel excavationDetector structure & buffer steel tanks competedAcrylic containers installedPMT test & installationDetector closing, installation of electronics & Dry runLiquid scintillator production & fillingStart data taking
20082009201020116116168
-
Neutrino Target(Gd+LS)Gamma Cather (LS)Buffer(Mineral Oil)VETO (Water)
-
Water filling for Veto Both near and far detectors are filled with Gd-LS, LS & mineral oil as of July 5, 2011.Veto water filling was completed at the end of July, 2011.
-
Recipe of Liquid Scintillator(to satisfy chemical, physical, optical properties, and safety requirements)
CnH2n+1-C6H5 (n=10~14)Gd Loaded Liquid Scintillator
Aromatic Solvent & FlourWLSGd-compoundLABPPO +Bis-MSB0.1% Gd+(TMHA)3(trimethylhexanoic acid)
-
Stability of Gd Concentration* Stable light yield : ~250 pe/MeV * Stable transparency at 430 nmNuclear Instruments and Methods in Physics Research A, 707, 45-53 (2013. 4. 11)
-
Software Trigger High DAQ efficiencySoftware trigger selects the events specified by using the timing information in each hit-data cell
timeEvent# (N-1)Event# NEvent# (N+1)17usecPeriodic Trigger
-
RENO Status Data taking began on Aug. 1, 2011 with both near and far detectors. (DAQ efficiency : ~95 %)A (220 days) : First q13 result [11 Aug, 2011~26 Mar, 2012] PRL 108, 191802 (2012)C (~700 days) : Shape+rate analysis (in progress) [11 Aug, 2011~31 Jul, 2013]B (403 days) : Improved q13 result [11 Aug, 2011~13 Oct, 2012] NuTel 2013Absolute reactor neutrino flux measurement in progress [reactor anomaly & sterile neutrinos]B (403 days) : Improved q13 result [11 Aug, 2011~13 Oct, 2012] NuTel 2013
-
Improvements in the Data Analysis
Statistics : -- about twice more data
Systematics : -- Improved background estimation/reduction (Li/He background, fast N, flasher events) -- Improved energy scale calibration
-
Energy Scale Calibration
-
Energy Scale CalibrationWe found a good calibration function for reactor energy scale.
-
Prompt signal (e+) : 1 MeV 2gs + e+ kinetic energy (E = 1~10 MeV) Delayed signal (n) : 8 MeV gs from neutrons capture by Gd
~26 ms (0.1% Gd) in LSSignature of Reactor Neutrino Event (IBD)Observed spectra for Prompt Signalm212 = 7.6x10-5sin2(212) = 0.8556m213 = 2.32x10-3sin2(213) = 0.113
-
Observed Spectra for Delayed Signal (n captured by Gd)
-
Detector Stability
-
Backgrounds Accidental coincidence between prompt and delayed signals Fast neutrons produced by muons, from surrounding rocks and inside detector (n scattering : prompt, n capture : delayed) 9Li/8He b-n followers produced by cosmic muon spallation
-
9Li/8He Background 9Li/8He are unstable isotopes emitting (b,n) followers and produced when a muon interacts with carbon in the LS. 9Li/8HeIBD
-
Background Spectra Background shapes and rates are well understood Total backgrounds : 6.5% at Far 2.7% at Near
-
Summary of Final Data Sample(Prompt energy < 10 MeV)
-
Expected Reactor Antineutrino Fluxes Reactor neutrino flux - Pth : Reactor thermal power provided by the YG nuclear power plant - fi : Fission fraction of each isotope determined by reactor core simulation of Westinghouse ANC - fi(En) : Neutrino spectrum of each fission isotope [* P. Huber, Phys. Rev. C84, 024617 (2011) T. Mueller et al., Phys. Rev. C83, 054615 (2011)] - Ei : Energy released per fission [* V. Kopeikin et al., Phys. Atom. Nucl. 67, 1982 (2004)]
-
Observed Daily IBD Rate Solid line is predicted rate from the neutrino flux calculation. Observed points have very good agreement with prediction. A new way to measure the reactor thermal power remotely!!!Reactor OFF
-
A clear deficit in rate (7 % reduction) Consistent with neutrino oscillation in the spectral distortionReactor Antineutrino Disappearance
-
Definite Measurement of Sin22q13 1st result(PRL)New result
-
RENOs Projected Sensitivity of q13 (5.6 s) (402 days)(18 % precision)
-
RENO measured the q13 successfully and stable data taking exceeded 600 days.RENO improved the systematic uncertainties and energy calibration after publication of the first result. -- The clear disappearance of the reactor antineutrinos.
-- New result with 5.6 s
SummaryRENO is preparing a new result based on shape analysis.RENO projects 3 years of data to improve the sensitivity of q13 measurement.
-
Thank you !
& Enjoy the conference and Seoul !
-
Comparison of Observed SpectraFinally, we can compare the number of rector anti-neutrino eventsobserved in our detector with the expectation from the reactor.
-
Detection Efficiency & Systematic Uncertainties
-
Cf Contamination Tiny fraction of Cf calibration source dissolved into Gd-LS after Oct. 13, 2012 : - Loose O-ring in the source container LS into the container Cf out of its disc package Cf contamination on gloves Cf contamination on the container surface & dissolved into LS - Cf at the bottom of target (confirmed by event vertex)
-
Cf Contamination Removal by a multiplicity cut & estimation by its energy shape
-
Observed Daily IBD RateIt is the accurate flux measurement.New methods for remote monitoring of reactor.
Cf contamination
-
IBD Prompt Signal (Data vs. MC)
-
***6 reactors are lined up in roughly equal distances and span ~1.3 km
***