1. NEUTRINO OSCILLATION MEASUREMENTS WITH REACTORS
R. D. McKeown
Caltech
NDM09
Madison, Wisconsin Sept. 4, 2009

2. Outline Reactor antineutrinos – generation, detection
KamLAND experiment and results
Reactor q13 experiments
Conclusions

3. Neutrino Studies with Nuclear Reactors
ne from n-rich fission products
detection via inverse beta decay (ne+pge++n)
Measure flux and energy spectrum

4. Discovery of the Neutrino – 1956
F. Reines, Nobel Lecture, 1995
"All you have to do is imagine something that
does practically nothing.
You can use your son-in-law as a prototype."

5. Detection Signal n + p g n + e+ g p + e 511keV 2.2 MeV d n
Coincidence signal:
Prompt: e+ annihilation g En=Eprompt+En+0.8 MeV
Delayed: n+p 180 ms capture time, 2.2 MeV
n+Gd 30 ms capture time, 8 MeV

6. The Reactor Neutrino Flux and Spectrum
235U, 239Pu, 241Pu from b measurements
238U calculated
Time dependence due to fuel cycle
~ 200 MeV per fission
~ 6 e per fission
~ 2 x 1020 e/GWth-sec
Reactor Isotopes

8. Precise Measurements Flux and Energy Spectrum g ~1-2 %
Reactors are calibrated sources of n ’s !!

9. The Motivation for KamLAND
Persistent observations of deficit of solar neutrinos
1998 – observation of oscillations of atmospheric neutrinos by Super-K
Unique opportunity to perform longer baseline reactor experiment in Japan

10. Enter Calibrated source(s) Large detector (1 kton)
Long Baseline (180 km)
Calibrated source(s)
Large detector (1 kton)
Deep underground (2700 mwe)

11. KamLAND uses the entire Japanese nuclear power industry as a
Kashiwazaki
KamLAND uses
the entire Japanese
nuclear power
industry as a
long­baseline source
Takahama
Ohi
Note: The neutrinos are free of charge!

12. Energy Spectrum

13. KamLAND Result (2008) Best combined fit values:
arXiv: v2 [hep-ex]
Best combined fit values:
Dm2 = x 10-5 eV2
tan2q =

14. Maki – Nakagawa – Sakata Matrix
Gateway to
CP Violation!
CP violation

15. CHOOZ/Palo Verde limits for 13
Allowed region
At m231 = 2.5  103 eV2,
sin22 < 0.15

16. Hints from Global Fits → sin22q13 ~ 0.06-0.08? Fogli, et al.,
arXiv:0905:3549
Also: A. B. Balantekin and D. Yilmaz,
J. Phys. G 35, (2008)
→ sin22q13 ~ ?

17. Theoretical Predictions for q13

18. ne Survival Probability
Dominant 12 Oscillation
near
far
Subdominant 13
Oscillation
“Clean” measurements of q, Dm2
No CP violation
Negligible matter effects

19. Reactor θ13 Neutrino Experiments
Chooz, France
RENO, Korea
Daya Bay, China
Angra, Brazil
Under construction.
Proposed and R&D.

20. 1051 m 380 m Two identical detectors:10 tons each.
Phase 1 (2010): Far Detector in
existing lab.
Phase 2 ( ): running with Near
detector in new lab.
1051 m
380 m
Status(July09):
PMT’s installed at far site
Acrylic vessels constructed
Veto under construction

21. Near Detector Tunnel Length 100 m 70 m Hill Tunnel Length 300 m 1.4 km
Far Detector
Near Detector
Tunnel Length 300 m
Tunnel Length 100 m
1.4 km
200 m Mt.
70 m Hill

22. Comparison Table Experiment Thermal Power (GW) Distances Near/Far (m)
Depth
(mwe)
Target Mass
(tons)
Start
Date
Sensitivity
@2.5x10-3 eV2
90% CL, 3 years
Double-CHOOZ
(France)
8.6
410/1050
115/300
8.8/8.8
4/2010, 2011
0.032
RENO
(So. Korea)
17.3
290/1380
120/450
15/15
2010?
0.02
Daya Bay
(China)
17.4
363(481) /
1985(1613)
260/910
40(2) / 80
2011
0.008

23. Daya Bay Nuclear Power Plant
4 reactor cores, GW
2 more cores in 2011, 5.8 GW
Mountains provide overburden to shield cosmic-ray backgrounds
Baseline ~2km
Multiple detectors → measure ratio

24. Experiment Layout Multiple detectors 20T per site cross-check
detector efficiency
Two near sites
sample flux from
reactor groups
20T
Total Tunnel length ~ 3000 m

25. Antineutrino Detector
SS Tank
Acrylic
Vessels
20 T Gd-doped
liquid scintillator
Calibration units
Gamma catcher
Buffer oil
192 8” PMT’s
3 zone design
Uniform response
No position cut
12%/√ E resolution

26. Muon Veto System RPC’s Water Cerenkov (2 layers)
Redundant veto system → 99.5% efficient muon rejection

27. Site Preparation Assembly Building Tunnel lining
Daya Bay Near Hall construction (100m underground)
Assembly Building
Tunnel lining
Portal of Tunnel

28. Civil Construction Status
Far Hall
Ling Ao Hall
Tunnel Entrance
Daya Bay Near Hall
Construction Tunnel

29. Hardware Progress Transporter SSV Prototype
4m Acrylic Vessel Prototype
Transporter
Calibration Units

30. Detector Assembly
Delivery of 4m AV
SS Tank delivery
Clean Room

31. Transporting the Prototype Detector

32. Sensitivity to Sin22q13 Experiment construction: 2008-2011
Start acquiring data: 2011
3 years running

33. Project Schedule October 2007: Ground breaking
August 2008: CD3 review (DOE start of construction)
March 2009: Surface Assembly Building occupancy
Summer 2009: Daya Bay Near Hall occupancy
Fall 2009: First AD complete
Summer 2010: Daya Bay Near Hall ready for data
Summer 2011: Far Hall ready for data
(3 years of data taking to reach goal sensitivity)

34. Sensitivity of q13 Experiments
Huber et al.,

35. Conclusions Reactor neutrino experiments have entered “precision era”
KamLAND provided the first “laboratory” evidence for neutrino oscillations, with a high precision measurement of Dm122
RENO, Double-CHOOZ, Daya Bay will study q13 during , with Daya Bay reaching sin22q13<0.01
If reactor experiments establish θ13 to be sufficiently large, Nova may then contribute unique sensitivity to the mass hierarchy in the next decade. In addition, the value of θ13 will provide necessary guidance to future accelerator-based long baseline experiments.

36. Stay Tuned !!