1. Current Status of RENO Soo-Bong Kim Seoul National Univ.
Feb. 27, 2008 at YongPyong

2. Neutrino oscillation parameters
(A new field of particle physics has begun!)
reactor and accelerator
13 = ? ?
CP = ?
SNO, solar SK, KamLAND
12 ≈sol ≈ 32°
0
atmospheric SK, K2K
23≈atm ≈ 45°
Large and maximal mixing!
Ue3

3. 13 from Reactor and Accelerator Experiments
- Clean measurement of 13
- No matter effects
mass hierarchy
CP violation
accelerator
matter
- sin2213 is missing key parameter for any measurement of CP

4. Reduction of reactor neutrinos due to oscillations
Disappearance
Reactor neutrino disappearance Prob. due to 13 with the allowed 2 range in m232
sin22q13 > 0.01 with 10 t •14GW •3yr ~ 400 t•GW•yr
(400 t•GW•yr: a 10(40) ton far detector and a 14(3.5) GW reactor in 3 years)

5. Reactor neutrino q13 experiment
Search for energy dependent ne disappearance using two (or more) detectors
Need to be located underground in order to reduce backgrounds from cosmic rays and cosmic ray induced spallation
The detectors need to be designed identically in order to reduce systematic errors to 1% or less

6. Detection of Reactor Neutrinos
data from CHOOZ
hep-ex/ v1
(1) 0.7<Eprompot <9MeV
(2) 5<Edelayed <11MeV
(3) 1μs<ΔT <200μs
e+ energy
n capture energy

7. RENO Collaboration Chonnam National University Dongshin University
Gyeongsang National University
Kyungpook National University
Pusan National University
Sejong University
Seoul National University
Sungkyunkwan University
Institute of Nuclear Research RAS (Russia)
Institute of Physical Chemistry and Electrochemistry RAS
(Russia)
+++

9. Schematic Setup of RENO at YongGwang

10. Google Satellite View of YeongGwang Site

11. Schematic View of Underground Facility

12. Schedule 사업내용 검출장비 설계 및 사양 결정 암반 지질조사 및 터널 설계 검출장비 제작 터널굴착 및 지하시설 구축
검출장비 시험가동
2006
2007
2008
2009 3 6 9 12

15. Comparison of Reactor Neutrino Experiments
Location
Thermal Power
(GW)
Distances
Near/Far
(m)
Depth
(mwe)
Target Mass
(tons)
Double-CHOOZ
France
8.7
280/1050
60/300
10/10
RENO
Korea
17.3
290/1380
120/450
15/15
Daya Bay
China
11.6
360(500)/1985(1613)
260/910
402/80

16. Efforts for Underground Facility
03~08, 2006 : Project description to local government, residents, and NGO’s (endorsed by local government)
03, 2007 : Agreement between KHNP and SNU
03~10, 2007 : Geological survey and tunnel design are completed.
12, 2007 : Public hearing for YG residents
01, 2008 : Safety regulation established and accepted by the atomic energy department of MOST
04~11, 2008 : Tunnel construction

17. Rock sampling (DaeWoo Engineering Co.)
Rock samples from boring

18. Rock quality map Near detector site: tunnel length : 110m overburden
height : 46.1m
Far detector site:
tunnel length : 272m
overburden
height : 168.1m

19. Stress analysis for tunnel design

23. Tunnel Excavation Schedule

24. Components of RENO Detector
Gamma catcher :
- LS
Target :
- Gd + LS
RENO실험은 원자력 발전소에서 발생하는 중성미자를 액체섬광 검출기를 사용하여
Inverse beta decay를 통해서 neutrino disappearance를 관측하는 실험이다.
RENO detector는 크게 inverse beta decay를 생성하는 target부분과 광생성이 일어나는 gamma catcher부분이 핵심적이고
Accidental Background 영향을 줄이는 Buffer부분과 muon과 같은 correlated background를 줄이는 veto부분이 있다.
Target 부분에는 neutron x-section이 큰 Gd을 첨가하여 검출효율을 높이는 동시에 background를 줄일 수 있다.
Liquid scintillator는 높은 광생성과 투명도, 그리고 장기적으로 안정해야 되고 radiopurity가 좋아야 한다.
Buffer :
- Non scintillating oil
Veto :
- Water

25. Detector Design with MC Simulation
RENO-specific MC simulation based on GLG4sim/Geant4
Detailed detector design and drawings are completed
Detector performance study & Detector optimization with MC:
- Gamma catcher size
- Buffer size
- photo-sensor coverage (no. of PMTs)
- neutron tagging efficiency as a function of Gd concentration
Reconstruction(vertex position & energy) program written
Systematic uncertainty & sensitivity study
Background estimation

26. RENO Detector Veto Buffer Target g-catcher total ~450 tons
Inner Diameter (cm)
Inner Height (cm)
Filled with
Mass (tons)
Target Vessel
280
320
Gd(0.1%) + LS
15.4
Gamma catcher
400
440 LS
27.5
Buffer tank
540
580
Mineral oil
59.2
Veto tank
840
880
water
354.7
total ~450 tons

27. RENO Detector

28. RENO Detector

29. Electronics

30. Detector Calibration & Monitoring

31. Reconstruction of Cosmic MuonsA B C D
Veto
(OD)
Buffer
(ID)
pulse height
time
OD PMTs
ID PMTs
target
buffer
g-catcher

32. Prototype Detector

33. Prototype Detector Assembly Filling with liquid scintillator
Acrylic vessels
Inner acrylic vessel
Mounting PMTs
Nitrogen flushing of LS
assembled prototype
Filling with liquid scintillator

34. Energy Calibration Using 60Co and 137Cs
DAQ & Trigger Logic
Radioactive sources
0.1

35. Mockup Detector

36. Mockup Detector

37. MC of Mockup Detector
60Co
137Cs

38. Gd+Liquid Scintillator R&D
General Elements of Liquid Scintillator :
Aromatic
Oil
Flour
WLS
Gd-compound
PC(Pseudocumene), PXE, LAB
Mineral oil, Dodecane, Tetrdecane, LAB
PPO, BPO
Bis-MSB, POPOP
0.1% Gd compounds with CBX or BDK
PC(20%) + Dodecane(80%) + PPO with bis-MSB or BPO
0.1% Gd compounds with CBX or BDK
R&D with the Russian INR/IPCE group (Gd powder supply)
Recipe with various mixture: performance (light yield, transmission & attenuation lengths), availability, cost, etc.
Design of purification system & flow meter
Long-term stability test
Reaction with acrylic?
R&D on LAB

39. R&D with LAB instead of PC/PXE + Dodecane
CnH2n+1-C6H5 (n=10~14)
Light yield measurement
High Light Yield : not likely Mineral oil(MO)
replace MO and even Pseudocume(PC) probably
Good transparency (better than PC)
High Flash point : 147oC (PC : 48oC)
Environmentally friendly (PC : toxic)
Components well known (MO : not well known)
Domestically available: Isu Chemical Ltd. (이수화학)
PC100% LAB100% PC40% PC20% LAB100% PC20%
N LAB60% LAB80% MO80%

40. Measurement of LAB Components with GC-MS
C16H C17H C18H C19H32
7.17% % % %
LAB : (C6H5)CNH2N+1
# of H [m-3] = x 1029
H/C = 1.66

41. Systematic Errors Systematic Source CHOOZ (%) RENO (%)
Reactor related absolute normalization
Reactor antineutrino flux and cross section
1.9
< 0.1
Reactor power
0.7
Energy released per fission
0.6
Number of protons in target
H/C ratio
0.8
0.2
Target mass
0.3
Detector Efficiency
Positron energy
Positron geode distance
0.1
0.0
Neutron capture (H/Gd ratio)
1.0
Capture energy containment
0.4
Neutron geode distance
Neutron delay
Positron-neutron distance
Neutron multiplicity
0.5
0.05
combined
2.7
< 0.6

42. RENO Expected Sensitivity
New!! (full analysis)
10x better sensitivity than current limit

43. GLoBES group workshop@Heidelberg – Mention’s talk
SK Dm2

44. Status Report of RENO
RENO is suitable for measuring q13 (sin2(2q13) > 0.02)
Geological survey and design of access tunnels & detector cavities are completed → Excavation will start in April 2008.
RENO is under construction phase.
Data –taking is expected to start in early 2010.
TDR will be ready in April of 2008.
International collaborators are being invited.

45. Back-up slides

46. Study on -catcher size
Gamma catcher thickness = 20cm
Gamma catcher thickness = 90cm
MeV
Gd capture
H capture
RENO
70cm: (94.28+/-0.54)%
60cm: (92.98+/-0.56)%
Daya Bay
45cm: 92%
Chooz
70cm: (94.6+/-0.4)%

47. Reconstruction : vertex & energy
Reconstructed vertex:  ~8cm at the center of the detector y
4 MeV (KE) e+
|y|
sy (mm)
Evis (MeV)
Energy response and resolution:
visible energy
PMT coverage, resolution
~210 photoelectrons
per MeV
1 MeV (KE) e+

48. Study on buffer thickness
Generate almost all energy lines from 232Th and 238U decay chains
Using activities of three nuclides
(238U = 0.70, 232Th = 0.41, 40K = 1.63 [Bq/PMT] (Hamamastu))
Sources of gamma are extended to be Target, Gamma Catcher and PMT
(PMT) Single Rates with 1 MeV Cut
Rsingle = Npmt×Ract×Navg×ε [Hz]
Gap [mm]
40K
232Th
238U
Total
500
3.4
8.0
11.2
22.6
600
2.0
5.3
7.1
14.4
700
1.4
3.9
5.1
10.4
800
0.8
2.7
3.6
900
0.5
1.6
1.9
4.0
1000
0.3
1.1
2.8

49. Calculation of Muon Rate at the RENO Underground
Jμ [cm-2s-1]
<Eμ> [GeV]
Far
250 m
2.9×10-5
91.7
200 m
8.5×10-5
65.2
Near
70 m
5.5×10-4
34.3
Muon intensity at the sea level using modified Gaisser parametrization + MUSIC or Geant4 (the code for propagating muon through rock)

50. Calculation of g Background at the RENO Underground
g rate from rock [Hz]
Double CHOOZ
Daya Bay
RENO
Rock
composition
(K) 1.6 ppm
(U) 2.00 ppm
(Th) 5.0 ppm
(K) 5 ppm
(U) 10 ppm
(Th) 30 ppm
(K) 4.0 ppm
(U) 4.8+/-1.8 ppm
(Th) 6.0+/-2.2 ppm
* Sample from Chongpyung.
Detector DxH Size [cm]
230x246 (10.3 m3)
320x320
280x320
Shelding
17 cm Steel
2.5 m Water
m Oil
Rates (K)
[Hz] (U)
(Th)
0.86
~0.89
0.98
0.26
0.65
2.6
(E>1 MeV)
0.21
0.53
1.74
(E>0.5 MeV)
Total rate
~2.73 Hz
3.5 Hz
2.5 Hz

51. PMT Test

52. Comparison of PMT performance