1. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Comparison of Reactor Sites and  13 Experiments Karsten Heeger LBNL

2. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Diablo Canyon Braidwood Reactor Sites in the US Daya Bay nuclear reactor 1-2 km Diablo Canyon Daya Bay

3. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Chooz, France ‘Double-Chooz’ Sensitivity sin 2 (2  13 ) < 0.03 at 90% CL after 3 yrs,  m atm 2 = 2 x 10 -3 eV 2 0.1-0.2 km 1.05 km ‘Double-Chooz’ Project 10-20 tons detectors 8.4 GW th reactor power 300 mwe overburden at far site 50 mwe overburden at near site

4. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Future Constraints on  13 Experiment sin 2 (2  13 ) When? CHOOZ< 0.11 NUMI Off- Axis (5 yr)< 0.006-0.0152012 JPARC-nu (5 yr)< 0.006-0.0152012 MINOS< 0.072008 ICARUS (5 yr)< 0.042011 OPERA (5 yr< 0.062011 Angra dos Reis (Brazil)< 0.02-0.03? Braidwood (US)< 0.02[2009] Chooz-II (France)< 0.03[2009] Daya Bay (China)< 0.012[2009] Diablo Canyon (US)< 0.02? Krasnoyarsk (Russia)< 0.016? Kashiwazaki (Japan)< 0.026[2008] Upper limits correspond to 90% C.L. let’s assume that Double-Chooz will be funded

5. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 A Second  13 Reactor Neutrino Oscillation Experiment? General Strategies two larger detectors in optimal location. eliminate dependence on reactor flux calculation need to understand relative acceptance of two detectors rather than absolute acceptance of a single detector. Issues Relevant for Evaluating Experiments reactor power baseline detector size (fiducial volume) - signal statistics - muon deadtime background relative uncertainty on acceptance relative uncertainty on energy scale and linearity What experiment do we need to exploit the full physics potential? Can we improve on Double-Chooz?

6. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Different  13 Experiments Scales of Experiments and Sensitivities small: sin 2 2  13 ~0.04  goal to make a fast discovery of  13 if just below the current Chooz limit. Entirely based on rate. medium: sin 2 2  13 ~0.01  make a discovery of  13 and determine if CP violation in lepton sector is observable.. Resolve mass hierarchy together with long baseline experiments. Complementary to J-PARC nu and off-axis experiments. Note: Experimental challenges to obtain sin 2 2  13 < 0.01 are difficult. large: sin 2 2  13 ~? What might the ultimate experiment look like?  Most precise measurement of  13. What are the possible strategies to reach these sensitivities?

7. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Reactor & Long Baseline Experiments Ref: NuMI Off-Axis Collaboration, Progress Report 12/2003 Measuring sin 2 (2  13 ) 3  Sensitivity to sin 2 (2  13 ) sin 2 (2  13 ) NuMI Off-Axis Minos Reactor Exp Chooz 90% CL sin 2 (2  13 ) ≤ 0.14 Minos 3-  sensitivity sin 2 (2  13 ) = 0.07  13 Reactor Exp sin 2 (2  13 ) < 0.01-0.02 90% CL NuMI Off-Axis 3-  sens. sin 2 (2  13 ) < 0.007 at  m atm 2 = 2.5 x 10 -3 eV 2 reactor 90% CL= 0.01 and  (sin 2 (2  13 )) = 0.006

8. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Reactor & Long Baseline Experiments Determining Mass Hierarchy   e appearance sin 2 (2  13 ) vs P( e ) for P( e )=0.02 sin 2 (2  13 ) Ref: NuMI Off-Axis Collaboration, Progress Report 12/2003 reactor 90% CL= 0.01 and  (sin 2 (2  13 )) = 0.006

9. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 How do you choose a reactor site?  Detector design and systematics will determine sin 2 2  13 sensitivity. Some General Criteria Reactor Power Baseline Detector Size Overburden Some sites place significant constraints on baseline and detector size: Chooz horizontal tunnel sites 2 vertical shafts Diablo Canyon Daya Bay Kashiwazaki Braidwood ~300 mwe < 700 mwe< 450 mwe

10. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Issues and Questions Overburden & Backgrounds 1. What are the minimum overburden requirements for near and far detector? Overburden requirements as a function of 2. What do we gain from having the same overburden at near and far detector? Baseline & Physics 3. Baseline and physics potential - distance - power - size - muon veto efficiency

11. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Constructing a Figure of Merit Signal Backgrounds I) Limit absolute background contribution to < 1% II) Measure backgrounds to < 1% and subtract

12. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Can we measure backgrounds? No of Reactors  B /S 24.15/  S  0.013 for 100k events 36/  S 47.8/  S II) Direct measurement during reactor refueling time: 3-4 weeks every 12-18 months 4-8% time for background measurement An optimistic estimate I) Measure background spectrum correlated with muon flux and neutron background high muon veto efficiency stability background statistics

13. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Constructing a Figure of Merit Oscillation Effect Deadtime Due to Spallation Cuts

14. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Detector Size Statistical Error  stat ~ 0.5% for L = 300t-yr Nominal data taking: 3 years (?) Interaction rate: 300 /yr/ton at 1.8 km Fiducial volume > 30 ton at 1.8 km ~60,000 ~10,000 ~250,000 Detector Event Rate/Year

15. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Overburden Chooz candidate events reactor on2991 reactor off287 Chooz has 9.5% irreducible background, presumably - fast neutrons, and - spallation backgrounds. bkgd depth (mwe) 10%300 400 560 730 Minimum overburden scaling Chooz background with muon spectrum that generates spallation backgrounds

16. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Muon Veto and Efficiency Chooz have 98% (?) > 99.5% possible (?) reactor on2991 reactor off287 event candidates bkgd muon veto efficiency 10%98% 2%99.5% < 0.5%99.9% Improvement in muon veto can reduce backgrounds. Note: Double-Chooz expects to have ~ 50% muon-related deadtime in near detector. Understanding muon veto efficiency and stability is critical.

17. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Muon Flux and Deadtime Chooz2% deadtime Muon veto requirements increase with volume, reduce with depth 100 t 50 t 25 t For a target of > 50 t perhaps we may want modular detectors (maybe 2 x 25 t detectors)? Small dependence on shape of detector.

18. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Oscillation Effect Baseline and Physics Sensitivity max oscillation measured oscillation max osc measured osc

19. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Requirements for Near and Far Detector Near Detector Far Detector measurement of backgrounds non-trivial dead time may be significant signal/background critical (> 100) signal/background important (> 100) baseline and oscillation sensitivity include dead time

20. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Reactor Power Thermal Reactor Power

21. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Baselines ? FarNear

22. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004 Site Comparison Far Detector Performance with and without Oscillation Effect w/ oscillation w/out oscillation

23. Karsten M. Heeger US Reactor  13 Meeting, March 15, 2004