Measuring q 13 with Reactors Stuart Freedman University of California at Berkeley

1. Measuring q13 with Reactors Stuart Freedman University of California at Berkeley SLAC Seminar September 29, 2003

2. q13 How to Weigh Dumbo’s Magic Feather I am going to argue that -- the fastest and cheapest way to determine the value of Sin22q13 is to measure two big things and subtract the results. - =

3. Neutrino LANDscape

4. Constraints from most recent Experiments

5. UMNSP Matrix 12 ~ 30° tan2 13 < 0.03 at 90% CL 23 ~ 45° Mass Hierarchy

6. What do we know and how do we know it Slide Courtesy of B. Kayser

7. Is it important to measure q13?

8. L. Wofenstein B. Kayser S. Bilenky S. Glashow A Smirnov Testimonials

9. absorber decay pipe detector p target horn + + + e e e Measuring13 Accelerator Experiments • appearance experiment • measurement of e and e yields 13,CP • baseline O(100 -1000 km), matter effects present Reactor Neutrino Oscillation Experiment • disappearance experiment • but: observation of oscillation signature with 2 or multiple detectors • look for deviations from 1/r2 • baseline O(1 km), no matter effects

11. Figuring out CP for leptons Minakata and Nunokawa, hep-ph/0108085

12. Basic Idea for a Disappearance Experiment ?

13. d2 d1 Detector 2 Detector 1 Reactor Experimental Design

14. First Direct Detection of the Neutrino Scintillator ne e+ n 2.2MeV n m Reines and Cowan 1956

15. Inverse Beta Decay Cross Section and Spectrum

16. 235U fission Neutrino Spectra from Principal Reactor Isotopes

17. 20 m KamLAND 4 m Chooz 1m Long Baseline Reactor Neutrino Experiments Poltergeist

18. CHOOZ

19. CHOOZ

20. KamLAND

21. KamLAND

22. Inverse Beta Decay Signal from KamLAND from 12C(n, g ) tcap = 188 +/- 23 msec

27. q13 at a US nuclear power plant? Site Requirements • powerful reactors • overburden • controlled access

28. Diablo Canyon Power Station

29. scintillator e detectors e + p  e+ + n coincidence signal prompt e+ annihilation delayed n capture (in s) e,, ~ 1.5-2.5km e < 1 km • • No degeneracies • • No matter effects • • Practically no correlations • E = Ee + mn-mp • Eprompt = Ekin + 2me • disappearance experiment • look for rate deviations from 1/r2 and spectral distortions • observation of oscillation signature with 2 or multiple detectors • baseline O(1 km), no matter effects

30. Overburden Essential for Reducing Cosmic Ray Backgrounds

31. Detector Event Rate/Year ~250,000 ~60,000 ~10,000 Statistical error: stat ~ 0.5%for L = 300t-yr Statistical Precision Dominated by the Far Detector

32. Diablo Canyon Variable Baseline 2 or 3 detectors in 1-1.5 km tunnel

33. IIIb IIIa Ge Geology II I • Issues • folding may have damaged rock matrix • - steep topography causes landslide risk • tunnel orientation and key block failure • seismic hazards and hydrology

34. Detector Concept muon veto acrylic vessel 5 m liquid scintillator buffer oil 1.6 m passive shield Variable baseline to control systematics and demonstrate oscillations (if |13| > 0)

35. 6 10 5 m Movable Detectors 1-2 km ~12 m • Modular, movable detectors • Volume scalable • Vfiducial ~ 50-100 t/detector

36. Kashiwazaki:13 Experiment in Japan - 7 nuclear reactors, World’s largest power station far near near Kashiwazaki-Kariwa Nuclear Power Station

37. Kashiwazaki:Proposal for Reactor 13 Experiment in Japan far near near 70 m 70 m 200-300 m 6 m shaft hole, 200-300 m depth

38. ~20000 ev/year ~1.5 x 106 ev/year Kr2Det: Reactor 13 Experiment at Krasnoyarsk Features - underground reactor - existing infrastructure Detector locations constrained by existing infrastructure Reactor Ref: Marteyamov et al, hep-ex/0211070

39. Systematic Uncertainties % Total LS mass 2.1 Fiducial mass ratio 4.1 Energy threshold 2.1 Tagging efficiency 2.1 Live time 0.07 Reactor power 2.0 Fuel composition 1.0 Time lag 0.28 e spectra 2.5 Cross section 0.2 Total uncertainty 6.4 % E > 2.6 MeV

40. . flux < 0.2% rel eff ≤ 1% target ~ 0.3% acc < 0.5% nbkgd< 1% Systematics Best experiment to date: CHOOZ Ref: Apollonio et al., hep-ex/0301017 Reactor Flux • near/far ratio, choice of detector location Detector Efficiency • built near and far detector of same design • calibrate relative detector efficiency variable baseline may be necessary Target Volume & • well defined fiducial volume Backgrounds • external active and passive shielding for correlated backgrounds Total syst ~ 1-1.5%

41. Optimization at LBNL ‘near-far’ L1 = 1 km L2 = 3 km ‘far-far’ L1=6 km L2=7.8 km MC Studies Normalization: 10k events at 10km Oscillation Parameters: sin2213 = 0.14 m2= 2.5 x 10-3 eV2

43. Sensitivity to sin2213at 90% CL cal relative near/far energy calibration norm relative near/far flux normalization Reactor I 12 t, 7 GWth, 5 yrs Reactor II 250 t, 7 GWth, 5 yrs Chooz 5 t, 8.4 GWth, 1.5 yrs fit to spectral shape Ref: Huber et al., hep-ph/0303232 Reactor-I: limit depends on norm (flux normalization) Reactor-II: limit essentially independent of norm statistical error only

44. Ref: Huber et al., hep-ph/0303232 statistics Statistics Systematics Correlations Degeneracies

45. Expected Constraints on13 Upper limits correspond to 90% C.L.