The H yper- K amiokande Experiment -Neutrino Physics Potentials- ICHEP2012 July 5 2012

1. TheHyper-KamiokandeExperiment-Neutrino Physics Potentials-ICHEP2012 July 5 2012 Hiroyuki Sekiya ICRR, University of Tokyo for the Hyper-K Working Group 1

2. Let’s answer remaining questions! PMNS framework Majorana phase x Dirac CP phase d octant of q23 mass hierarchy matter potential Through the oscillation can reach all of them Using both accelerator and atmospheric ns

3. Kamioka 3rd Generation 1Mt Water Cherenkov Detector Fiducialvol.0.56Mt SK x 25 Fiducial vol. 0.0225Mt • 2 cylindrical tanks lying side-by-side (48m x 54m x 250m each) • 5 compartments in each tank w/ photo-sensitive separation walls • Each compartment is “twice the size of Super-Kamiokande II” • ID 20% photo-coverage with 99,000 20” PMTs • OD 2m layer with 25,000 8” PMTs 41.4m 39.3m

4. _ _ The channel nm→ne,nm→ne Oscillation term Leading sin22q13 CPC Measured angles CPV Solar matter neutrino Anti-neutrino L=295km , r=2.6g/cm3 case (assuming IH, d=p/2)

5. The Cherenkov method • Well established e-m separation m-like e-like ex) Super-Kamiokande IV Multi GeV 1 ring sample sharp edge ring blurred edge ring Separation power >99%@1GeV Particle identification of e and μ

6. Accelerator n from J-PARC • 2.5o off-axis high intensity n beam cite candidates in Kamioka HyperK SuperK ~0.6GeV nm 2700mwe 295km 1750mwe J-PARC J-PARC 30GeV proton beam power will be upgrade to 0.75MW

7. Expected spectrum (d dependence) NH, sin22q13=0.1 _ nmode 7.0 years nmode 3.0 years Signal efficiency is 64% nm CC BG rejection > 99.9%, NC p0 rejection >95% Full MC (beam,n interaction, detector, reconstruction)

8. Sensitivity to CP violation _ Run time n:n = 3:7 5% systematic error is assumed. cf. Systematic error of T2K:10% Chance to observe CP violation >3s d=0 exclusion (CPV sensitivity) in true d-q13 space p HK 5 year HK 10 year 0.75MWx10 years d 0 Fraction of d in [-p,p] -p 10 years operation if MH is known by then 74% chance to observe CPV

9. Sensitivity to Mass Hierarchy _ • “J-PARC+Hyper-K” only Run time n:n = 3:7 5% systematic error is assumed. MH sensitivity (IH exclusion for true NH case) in true d-q13 space 0.75MWx10 years N.B. Do not multiply 43% bf 74%! 10 years operation 43% chance to determine the MH.

10. Atmospheric n cosQ = 1 L～15㎞ Q cosQ= -1, L～13000㎞ En<～1.3GeV ne:nm=1:2 Region of interest is Multi-GeV, upward(Q<0) cosQ Free neutrino source Very long base line (in matter) Wide energy range

11. Statistical PID _ _ _ ne-like ne-like ne-pulity 36.7% ex) Super-K IV Multi-GeV 1ring e-like CCnonQE interactions MC Number of decay-e >0 ne-like + SK 4 data (448.6 days) Number of decay-e =0 anti ne-like Number of decay-e ne-pulity 60.5% Water Cherenkov detector can separate ne from ne statistically.

12. Expected zenith angle distributions for Ne/N0e (MH, q23) Full MC Multi-GeV ne-like Multi-GeV anti-ne-like MH difference (btw solid and dashed )is clearly visible.

13. Sensitivity to Mass Hierarchy Inverted hierarchy case Normal hierarchy case Hyper-K 10 years Hyper-K 10 years sin2q23=0.6 sin2q23=0.6 Dc2 for assuming Inverted Dc2 for assuming Normal sin2q23=0.5 sin2q23=0.5 sin2q23=0.4 sin2q23=0.4 3s 3s 10 years operation For most cases, MH is determined Significance ≡ Dc2 for wrong MH assumption

14. Sensitivity to q23 octant sin22q23=0.96 case sin2q23=0.4 or 0.6 sin22q23=0.99 case sin2q23=0.45 or 0.55 Hyper-K 10 years NH 90%CL Hyper-K 10 years NH 90%CL : assumed true parameter 10 years operation Could be discriminated even for sin22q23=0.99

15. Other Physics Topics • Supernova relic neutrino (DSNB) • Supernova burst neutrino Gd load option • WIMP search • Solar neutrino • Neutrino geophysics Nucleon decay search

16. Technical R&D • Water purification system • Water tank • Photo sensor • 8 inch HPD is in testing • 20 inch HPD is under development • electronics Photo tube (cathode) APD Hamamatsu Large cavern excavation

17. Conclusion Open Hyper-K Meeting August 21-23, 2012 Kavli IPMU, Kashiwa, Japan All those interested are welcome to join the meeting! It’s time to start next generation n detectors. A mega ton water Cherenkov detector, Hyper-Kamiokanadeprovides a very rich physics program. Can be realized with well-established technology. Open Hyper-K meeting will be held.

18. Extra slides

19. Possible Schedule

20. Accelerator n selection criteria CCQE

21. BG _ ne contamination in n mode

22. MC Expected number of event _ • n mode 7 years n mode 3 years

23. Accelerator nc2 i: Energy bin index (per 50MeV) fX: systematic parameters Ni: # of events for i-th bin with “true” set of parameters ni: # of events for i-th bin with “test” set of parameters σX : systematic errors for corresponding fX(5% are assumed)

24. Expected allowed region Assuming true is (d=p/2, sin22q13=0.1 )

25. IF MH is unknown Two degeneracy region Assuming true is (d=p/2, sin22q13=0.1 )

26. q13 dependence of d measurement Too large q13 is not so helpful…

27. Atmospheric n 3 flavor oscillation

28. Atmospheric n MSW resonance _ nefor NH, ne for IH

29. Statistical PID Multi-ring case: Liklihood method

30. Statistical PID

31. MC Expected number of ne-like, ne-like _

32. Atmospheric nc2

33. Expected zenith angle distributions for Ne/N0e (d) Full MC Multi-GeV ne-like Multi-GeV anti-ne-like d difference is visible.

34. Sensitivity to d atmospheric n by itself

35. Super-K atmospheric event categories