Status of RENO Yeongduk Kim Sejong University International Workshop on Nuclear, Particle and Astrophysics Yongpyong, Feb. 24, 2010

Outline Neutrino mixing and mass Θ 13 Reactor neutrino experiment. RENO Status – lots of pictures. Perspectives. 2

Neutrino Mixing 3 Atmospheric ( ν μ  ν x ) Solar ( ν e  ν x ) Not measured Probability of flavor oscillation depends on mixing angle & mass difference square, neutrino energy, baseline. e  

Νeutrino mass 0  e–e– e–e– uddu ( ) R L WW (1) Single Beta Decay end point is sensitive to neutrino mass ; m β (2) Double Beta Decay experiment is sensitivie to neutrino mass ; m ββ

Still we don’t know about ν in 1.Majorana or Dirac – Double beta decay(DBD) exp. 2.Absolute mass – DBD or Beta 3.Mass ordering(Hierarchy) – LBL or Reactor 4.Θ 13 – Reactor or LBL 5.CP Phase - LBL

Mass Hierarchy Hirsch et al, PLB679: ,2009  m A ~45meV  m S ~9 meV m3m2m1m3m2m1 m 2 m 1 m 3 NH IH e      13 ? Depending on the mass hierarchy, the effective neutrino mass to be measured is very different.

Hints for θ 13 >0 7 Fogli et al. hep-ph/

sin 2 θ 13 = / Fogli et al. hep-ph/

9 Neutrino Production in Reactors n U 235 U 236 * n n Zr Cs I 140 Te 140 Xe 140 Rb 94 Sr 94 Y e - e - e - e - e - e - e e e e e e are produced in  -decays of fission products. Nakajima et al., NIM A569, 837(2006) Reactor  spectra Detected  spectra 4 isotopes contributes more than 99.9%

10 Reactor Neutrino Experiment at a Glance  13 Dominant  12 Dominant “near” “far” Inverse Beta Decay p ν e e + n Gd γ γ γ γ ~30μs Delayed signal E  ~ 8 MeV  γ γ prompt signal sin 2 (2  13 )=0.04 sin 2 (2  13 )=0.1 sin 2 (2  13 )=0.2 E (MeV)

Comparison of Reactor Neutrino Experiments ExperimentsLocati on Therm al Power (GW) Distances Near/Far (m) Depth Near/Far (mwe) Target Mass (tons) Double- CHOOZ France8.7280/105060/30010/10 RENOKorea / /45016/16 Daya BayChina (500)/1985(16 13) 260/  2/80

12 Critical points for sin 2 (2  13 ) Low background: –3 main sources : cosmogenic( 9 Li), fast neutron, accidental coincidence –Deep underground for reducing cosmogenic background –Purer materials for low background at E<10 MeV to reduce accidentals Reduce systematic uncertainties: –Reactor-related: near and far detectors configuration canceling reactor uncertainties Ramaining uncertainties due to multiple reactors –Detector-related: Identical detectors should be confirmed by precise calibration Long-term stability of detectors should be confirmed.

Neutrino Laboratories in Far East 13  13 SK Θ 13 exp RENO DAYA BAY Double Beta CANDLES( 48 Ca) CaMoO4 ( 100 Mo) CDUL : New Lab.

14 RENO reactor detector m m ~256 m ~ Yonggwang Nuclear Power Plant Six ~ 1 GW e class PWRs Total average thermal power of 16.4 GW (max 17.3 GW) Started operation in 1986~2002. Operational factor > 90%

Target(acrylic, 2.5cm) Buffer(SUS) 6mm GC(acrylic, 3.5cm) Veto(Concrete+epoxy) 30cm ID PMT(10”) OD PMT(10”) Detector Overview

Tunnels, Infra & SUS Tanks

Buffer SUS Tank – Geosan Steel Engineering

Tunnels, Infra & SUS Tanks Overground Laboratory Apartments

Acrylic Structures – almost complete TARGET Tanks – KOA Tech.

Acrylic Structures – almost complete Gamma Catcher Lid

Acrylic Structures – almost complete Moving Gamma Catcher Tanks

Lower part of Gamma Catcher in the Tunnel

Lower part of Gamma Catcher inside buffer tank

Multiple(12) PMT test facility Inside TunnelVisible light Splitter (1  12 outputs) 100 micrometer multimode fibers

Magnetic Field effect on PMTs Earth magnetic field(~0.45G) is not serious problem. But, other magnetized material in the room is serious. Setup to compensating Earth Magnetic Field & Generating artificial B Field. For Bz=1G

PMT holder + Mu metal(0.3mm thick) Mu-metal will be up to the end of photocathode.

HV supplying system 28 CAEN A1932AP – 48 channels, 0.5mA/ch, compact multipin connector. 18 modules/detector Delivery until May Deoupling Box 48/channels

Light source calibration Diode Laser + Optical Fiber Multiplexer + Collimating lens Will be installed at the surface of SUS tank, real-time calibration. 440nm 1ns pulse width Single mode Fiber output 1x16 programmable multiplexer Buffer Tank

Data with a proto-type detector 30

ABSLENGTHOPSCATFRACABSPROB LAB emissionPPO emissionbis-MSB emission Optical parameters of liquid scintillator. Absorption & Emission spectra measured. Liquid Scintillator

Liquid Scintillator Filling. 32

Schedule Liquid filling GdR3 & LS Production PMT test Handling system delivery Washing & construction 2010 PMT Mount Closing Structure & Calibration system Install Electronics

Sensitivities & discovery potential 34 Huber et al., hep-ph/

35 ERICE08 Suekane

36 Summary Neutrino mixing parameter  13 is important for lepton sector CP violation, neutrino mass. 0 nu Double beta decay depends neutrino mass hierarchy. If sin 2 (2  13 ) > 0.02, Double Chooz, RENO, DAYA BAY can tell the value until Mass hierarchy may be accessible with kTon 50km base line if sin 2 (2  13 ) > 0.02

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39 Possibilities for  13 measurement  Reactor e disappearance while traveling L ~ 1.5 km. – look for small e disappearance from large isotropic flux P( e  e )  1 - sin 2 (2  13 )sin 2 (1.27  m 2 atm L/E) L/E ~ 500km/GeV. This process depends on  13 alone. A relatively modest- scale reactor experiment can cleanly determine whether sin 2 2  13 > 0.01  Accelerator   e while traveling L > several hundred km. –look for small e appearance in μ beam P(   e  sin 2 (2  13 )sin 2 (  23 )sin 2 (1.27  m 2 atm L/E) L/E ~ 400 km/GeV. This process depends on  13,  23, the CP phase , and on whether the spectrum is normal or inverted. (T2K experiment)

Daya Bay Reactors Ling Ao Reactors Ling Ao II Reactors Liquid Scintillator hall Entrance Construction tunnel Water hall Empty detectors: moved to underground halls via access tunnel. Filled detectors: transported between halls via horizontal tunnels. 295 m 810 m 465 m 900 m Daya Bay Near Overburden: 98 m Total tunnel length ~ 3000 m Far site Overburden: 355 m Ling Ao Near Overburden: 112 m (Starting 2011) DAYA BAY

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4 m Acrylic Vessel Status: Experimental Components Detector Transporter Stainless Steal Vessel Link, Neutrino Champagne 2009

Neutrinos 43 Nuclear beta decay Atmospheric ν Solar ν Accelerator ν Reactor ν