SHORT BASELINE NEUTRINO OSCILLATION EXPERIMENT IN KOREA Yangyang Yeongduk Kim Sejong University For HANARO-SBL collaboration.

2 2 Contents 3 Neutrino Oscillations Indications of Sterile Neutrinos Theta13 measurement - RENO Sterile Neutrinos w/ HANARO Reactor Summary

3 중성미자 진동을 발견하면, 그 섞임각과, 질량차이를 알 수 있다. Flavor 가 변하지않고 살아남을 확률은, 진동이 일어나는 L/E 값에서 질량차이를 알수 있다. 진동이 일어나는 Amplitude 로 부터 섞임각을 알수 있다.

4 3 neutrino mixing and oscillations  The oscillation due to 3 rd mixing angle is maximum at the same L/E as atmospheric neutrinos. ~45meV ~9meV

5 5 4 th, Sterile Neutrinos ? 1.LSND, MiniBoone  Experiment 2.Artificial Neutrino Source anomaly 3.Reactor Neutrino anomaly

6 Sterile-active neutrino oscillation - Gouvea  Sterile neutrinos – right-handed neutrinos  Sterile neutrinos – maybe Warm Dark Matter  Nothing is known about the masses. Maybe very light (m >10 10 GeV)

7 7 [1] LSND

8 8 Miniboone

9 9 [2] Radioactive Source Anomaly ? - Giunti There was some deficit in the counts of artificial neutrino source calibration of neutrino detectors.  Large mixing angle at large mass difference.

10 Sterile-active neutrino oscillation – Gouvea,Giunti ~45meV ~9meV If, quasi 2 case,

11 The three effective mixing angles are correlated.

12 Energy spectra of reactor neutrinos 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. 반응단면적 검출된 스펙트럼 중성미자 스펙트럼 중성미자 스펙트럼 X 반응단면적 = 검출된 스펙트럼 검출된 스펙트럼으로부터 원자로의 연료상태를 연구하거나, 중성미자 진동현상을 연구하기 위해서는 중성미자 스펙트럼을 정확하게 알고 있어야 한다. ( 단면적은 이론적으로 잘 알고 있음.)

13 ExpPFuelDetectorMassyearLT# eventseta GW(m)(days) On-Off /day On-Off % Bugey Li+LS(NE320)600L Bugey4 3 He+H 2 O15 Goesgen2.8 3 He+LS ILL % 3 He+LS PSD 377L ROVNO %Gd-LS238L k32 Krasnoyarsk 3 He+PE Palo Verde JOYO %Gd-LS 10% BC521+PC 900L SRP2.0Gd-LS(0.5%) PSD 275L Past Experiments

14 ILL Experiment ILL Exp. : L=8.7m Old, Shortest Baseline Reactor neutrino experiment, yet it indicates some oscillational pattern !!

15 KAMLAND Data CHOOZ Data Double Chooz(FRANCE) Daya Bay(China) RENO(KOREA) Before Reactor Spectrum modified  6% deficit !! [3] Reactor Neutrinos

16 All combined Mention et al., arXiv: (2011)

17 HANARO research reactor Cross section ~ cm 2 ~ 1 event / (1ton 1day 1GWth 1km RENO : 15Ton,  150 events/day HANARO : 0.5Ton, 5m  600 events/day

18 Short Baseline HANARO  HANARO : 30MW research DAEJON  Locate at shortest baseline from reactor.  Utilize PSD (Pulse Shape Discrimination) power  Background reduction will be done at outside of the reactor with the full Setup.  A prototype detector (50L) will be tested first for background confirmation. Sejong University : YDKIM, EJJEON, KJMA, JYLEE, JYKIM KyungPook National University : HJKIM, JYLEE Chonnam National University : KKJOO Seokyung University : KSPARK HANARO : CHLEE, +……

19 Simulations Assume Total Event Rate

20 Ratio in energy spectra between two distances Data at two distances can be compared. --- Oscillation --- No Oscillation

21 Core Size dependences

22 If larger mass difference, small core size is important. !

23

24 Detector Design

% 6 Li or Gd-LS ? p n 6 Li ~30μs Delayed signal γ γ prompt signal 30  s 4.8 MeV (0.6 MeV Visible) 1-8 MeV t

26  UG 의 경우 compound 로 인한 quenching 이 적다.  LiCl 중 Li 의질량은 약 0.016g 이고 전체 용액대비 0.16%, LiBr 의 경우 Li 의 질량 은 0.008g 이고 약 0.08% 를 차지한다.  LiCl 의 질량 중 Li 의 비는 약 16.4%, LiBr 의 질량 중 Li 의 비는 약 8% 이다. Inorganic Compounds Loaded LSC

27 UG-AB N-Gamma PSD Lab-ls OF-O UG-F (Neutron Gate = 0.8MeV ~1.2MeV) PSD of Safer Scintillator

FOM_UG-f=4.5 FOM_Lab-LS=3.0 FOM_OF-O=3.1 FOM_UG-AB=4.5

RENO Detector  ” Inner PMTs : 14% surface coverage  67 10” Outer PMTs D (cm) H (cm) vessel Filled with Mass (tons) Target280320Acrylic Gd(0.1%) +LS 15.4 Gamma catcher AcrylicLS27.5 Buffer540580SUS Mineral oil 59.2 Veto Concret e water354.7

30 Milestones in 2011 Detector closing (Jan.) Installation of electronics hut & control room (Feb.) DAQ electronics & HV supplying system, & cabling (Feb.) Dry run & DAQ debugging (Mar. ~ Jun.) Installation of slow control and monitoring system (Jan. ~ Jun.) Installation of Liquid scintillator production system (Jan. ~ Apr.) Liquid scintillator production & filling (May ~ Jul.) Glove box installation (Jul. ~ Aug.) Installation of 3D calibration system (Jun..~ Jul.) Installation of water circulation system (Jul. ~ Aug.) Began regular data-taking & calibration (Aug. 1 ~)

31 Gammas Preliminary 68 Ge 60 Co 137 Cs center. ~ 230 PE/MeV 14% photocathode coverage Far Near (gain 2%)

Cf - neutron Preliminary Far Near (gain 2%) Gd(n,g) neutron capture signal p(n,g) neutron capture signal

33 * Sensitivity : sin 2 (2  13 ) > 0.02 at 90% C.L.  Statistical errors (3 years of data taking with 70% efficiency) Near : 9.83x10 5 ≈ 10 6 (0.1% error) Far : 8.74x10 4 ≈ 10 5 (0.3% error)  Systematic error : <0.5% 90% CL Limits RENO Sensitivity on sin 2 (2  13 )

34 Sterile neutrinos at RENO Both RENO detectors will see the deficit of neutrinos if sterile neutrinos exist. No L/E sensitivity except 0.1 eV 2

35 Short baseline experiments

37 Source locations: 3 options  “ Icarus Pit ” - IP  A pit built right below the W.T.  Access tunnel ready  8.25 m from detector center  “ Water Tank ” - WT  Access from flanges on top  Source would be in water  7 m from detector center  “ Detector Center ” - DC  Possible at the end of Borexino solar neutrino program  More effort, but much higher sensitivity LNGS, Beyond Three Families - May 4 th, 2011M. Pallavicini - Dipartimento di Fisica - Università di Genova & INFN pit tunnel ν or ν WT: 7 m DC

38 요약  It is tempting to confirm the claims about sterile neutrinos.  At HANARO reactor, neutrino detection can be done as close as 5m.  With full power of PSD, the background reduction seems to be possible.  Background studies can be done at other places.

Cs 68 Ge 60 Co 252 Cf Far Detector Calibration

근거리 source data Cs Ge Co Cf

41 RENO Sites reactor detector m m ~256 m near detector site 46.1 m 95 m far detector site m 272 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%

Combined Reactor Rate+Shape contours 42 D. Lhuillier - Beyond 3 neutrinos - May 2011 No oscillation disfavored at 96.51% Best fit: sin 2 2  ~0.1  m 2 ~1.5 eV 2 excluded area allowed

43 Near : Jan. 21, 2011 Far : Jan. 24, 2011 Detector Construction & Closing (Jan. 2011)

44 Liquid Scintillator Production System Control Room DAQ Electronics Calibration System Completed RENO Detector (Feb. 2011)

45 Dry Run Charge(counts) discri. thr. -0.4mV -0.5mV -0.6mV -0.7mV -1.0mV Before Filling Liquids,

46 Gd-LS & LS Goal Gd-LS : 0.1% Gd, PPO 3g/L, bis-MSB 30mg/L  TARGET LS : PPO 3g/L, bis-MSB 30mg/L  GAMMACATCHER Concentrated Liquids Gd-LAB : 0.5% Gd ( X5 concentration) LS-Master : PPO 30 g/L, bis-MSB 300mg/L ( X10 concentration) LS batch (2000L) LAB (1800 L) + LS-Master (200L) Near/Far separate production & filling Gd-LS batch (2000L) LAB (1400 L) + LS-Master (200L) + Gd-LAB (400L) Produced in Far detector area and divided two

GdLS (0.1 %) 2000L LS master (x10) 200L Gd-LAB (0.5%) 400L Gd-sol TMHA LS 2000L LAB 10ton Water out Divide two G.C. FAR LS master (x10) 200L LS 2000L LAB 10ton Water out G.C. NEAR

48 LS handling system

49 Water filling for Veto DAQ Electronics Gd-LS filling for Target Gd Loaded Liquid Scintillator LS filling for Gamma Catcher Both near and far detectors are filled with Gd-LS, LS & mineral oil as of July 5, Veto water filling is completed at the end of July, Liquids Production & Filling

50 veto Circulation system Drain Local Water supply Solenoid valve : Auto on/off Feedback from the ultrasonic level sensor of Water level Water circulation system

51 Gain matching of PMTs 137 Cs source in the center. PMT gains are set to 1.0x10 7. gain variation between PMTs are within 3% for both detectors. Gain (10 7 )

52 Calibration Sources typesourceE(keV)calibration gamma 137 Cs662threshold e+e+68 Ge511(2)Position, E threshold gamma 60 Co Multiple gamma neutron 252 CfNeutron+8MeV gammas Neutron efficiency Gd concentration

53 Laser calibration system Blue(420nm) Laser + Fiber optics Top, Barrel) BarrelTop Bottom Laser

54 1-D source driving systems

55 wire pulley (circumference ~ 1 m) passive pulley active(motor) pulley source case (acrylic) weight (teflon) glove box Control system Mechanical system 1D system 구성

56 Summary Construction of both near and far detectors are completed in Feb All the liquids including Gd-LS are produced and filled as of July 5, Dry runs were performed to check PMTs and DAQ in March ~ May, Background data-taking has been made since the middle of June, Regular data-taking with near & far detectors began from August 1, Data reduction and calibration efforts are on progress.

57 Examples with 90 Sr in the center LNGS, Beyond Three Families - May 4 th, 2011M. Pallavicini - Dipartimento di Fisica - Università di Genova & INFN Δm 2 = 1.0 eV 2 sin 2 (2 ϑ s ) = year Δm 2 = 2.0 eV 2 sin 2 (2 ϑ s ) = year Δm 2 = 2.0 eV 2 sin 2 (2 ϑ s ) = year Δm 2 = 1.0 eV 2 sin 2 (2 ϑ s ) = years

58

59  13 를 위한 원자로 중성미자 실험 동일한 검출기를 1,3 최대진동 위치와 아주 가까운 위치에 놓고 실험.  13 Dominant  12 Dominant “near” “far”