1. Superbeam long baseline experiments Takashi Kobayashi KEK 100830 Neutrino Summer School @Tokai

2. 2 e   Flavor eigenstates m1m1 m2m2 m3m3 Mass eigenstates 6 parameters  12,  23,  13,   m 12 2,  m 23 2,  m 13 2 3 flavor mixing of neutrino Unitary matrix 2  m ij =m i 2 -m j 2

3. T.Kobayashi (KEK) 3 Known and Unknowns OR Solar & Reactor  12 ~33 o  m 12 2 ~0.00008eV 2 Atomspheric + Acc  23 ~45 o  m 23 2 ~0.0025eV 2Unknown!  13 <10 o  13 <10 o (  m 13 2 ~  m 23 2 )? (  m 13 2 ~  m 23 2 )?  ???  ??? 1 2 3 Mass hierarchy e ??

4. 4 Unknown properties of neutrino 4   13 ?  Last unknown mixing angle   T2K, NOvA, Double Chooz, RENO, DayaBay  CP invariance ?  Mass hierarchy ?  Absolute mass  Tritium beta decay, double-beta  Majorana or Dirac?  Double-beta Next generation accelerator based expriemtns

5. Toward unraveling the mystery of matter dominated universe 5

6. Sakharov’s 3 conditions To generate Baryon asymmetry in the unverse  There is a fundamental process that violates Baryon number  C and CP invariance is violated at the same time  There is a deviation from thermal equilibrium acting on B violating process 6

7. Toward origin of matter dominated universe  Quark sector CPV is found to be not sufficient for reproducing present baryon content  Scenario for baryogenesis through lepton CP violation: Leptogenesis  CPV in lepton sector is responsible for B genesis  CPV in neutrino oscillation could provide a key to unravel mystery of origin of matter 7

8. Let’s find CPV in lepton sector  I give you  1000 億円 or  1.2 Billion USD  755M GBP  55 Billion INR  1,401 Billion Won  2,130 Billion Peso  7.9 Billion 元  918 Million Euro  35 Billion Ruble  1.2 Billion CHF 8 Let’s design an experiment to search for CPV in lepton sector If you find any good idea, let’s write a paper! One condition: Within 10years

9. How? …. : Q1  Do we really need oscillation phenomena to probe CPV??  Can’t we attack CPV in an experiment which fit in an experimental hall like such as Kaon CPV or B CPV  Why?? 9

10. Measuring CPV in quark sector  Through loop diagram  Amplitude ∝ (m u,c,t /M W ) 2  Please calculate  Since quark is heavy (especially top), this process becomes measureable 10 W W s,b d u,c,t s,b W u,c,t V CKM

11. How about lepton sector?  Amplitude ∝ (m /M W ) 2  Standard model process STRONGLY suppressed  Thus, good field to search for physics beyond standard model 11  W e, ,  V MNS e  Example:   e 

12. Oscillation 12 l l ’ 1 2 3

13. Oscillation (cont) 13 If E i are same for all mass eigenstates E Ei’s are same, no oscillation, in other word, Ei’s are different, we can probe mixing matrix through oscillation Difference of Ei, ie, phase advance difference is essential For  m 2 ~10 -3 eV 2

14. 14 B.Kyser, in this SS

15. Q2: What oscillation process is best?  OK, now, we somehow understand we need (long baseline) oscillation phenomena to probe matrix elements and attack CPV.  What type of oscillation is best?  Fundamental physics reason  Experimental feasibility 15

16. Disappearance ? Appearance? 16 Oscillation probability Disappearance case There is no place for complex phase  in U MNS to appear Disappearance has no sensitivity on (standard) CPV

17. Appearance  Conventional  beam (~GeV)    e  Not yet discovered      Dominant oscillation mode  Neutrino factory/Beta beam (~10GeV)  e    e   17 Next talks

18. e vs  appearance 18 Oscillation probability (w/ CPV) Relative effect of CPV CP conserved part CPV part     case,  probability A ∝ sin 2 2  23, is known to be large, relative effect of CPV becomes small  Also experimentally, identification of nt (out of lots of nm interactions ) is not easy  For nue appearance, A ∝ sin 2 2  13 is known to be small   Large CPV effect expected

19. Matter effect 19 e Z e X X e W e- e  Z  X X  Z  X X NC Interactions through propagation in matter CC

20. Matter effect 20  Relative size of effect ∝ E  Change sign when  m 2 sign change: Can probe sign  Change sign when ⇔ bar: Fake CPV effect

21. 21 Oscillation probabilities contribution from  m 12 is small e appearance (LBL/Atm)  disappearance (LBL/Atm) e disappearance (Reactor) when 1 2 3  m 23 2 (No CPV & matter eff. approx.) ~1 ~0.5 ≪1≪1 Pure  13 and  m 13 2  13 and  m 13 2  23 and  m 23 2

22. 22   e appearance & CPV   , a  -a for Matter eff.: CP-odd Solar Main Matter # of signal ∝ sin 2  13 (Stat err ∝ sin  13 ), CP-odd term ∝ sin  13 Sensitivity indep. from  13 (if no BG & no syst. err)

23. 23 Takashi Kobayashi (KEK), PAC07 23 All mixing angle need to be non-zero   , a  -a for Matter eff.: CP-odd Leading CPV effect (where sin  12 ~0.5, sin  23 ~0.7, sin   <0.2) + other terms.. Same as Kobayashi-Maskawa model which require 3x3 to incorporate CPV

24. 24 CPV vs matter effect 295km730km Smaller distance/lower energy  small matter effect Pure CPV & Less sensitivity on sign of  m 2 Combination of diff. E&L help to solve.   e osc. probability w/ CPV/matter @sin 2 2  13 =0.01

25. Lepton Sector CP Violation Effect of CP Phase δ appear as – ν e Appearance Energy Spectrum Shape *Peak position and height for 1 st, 2 nd maximum and minimum *Sensitive to all the non-vanishing δ including 180° *Could investigate CP phase with ν run only – Difference between ν e and ν e Behavior 25

26. How to do experiment? OK, we now understand  Importance of CPV in lepton sector  Necessity of oscillation to probe CPV  What process is suited for CPV measurement  Behavior of oscillation probabilities and relevant physics So, now, let’s consider more on experimentation! 26

27. Super Beam Conventional neutrino beam with (Multi-)MW proton beam (  Fact)  Pure  beam ( ≳ 99%)  e ( ≲ 1%) from     e chain and K decay(Ke3)     can be switched by flipping polarity of focusing device 27 Proton Beam Target Focusing Devices Decay Pipe Beam Dump  ,K,K  Strongly motivated by high precision LBL osc. exp.

28. 28 High intensity narrow band beam -- Off-axis (OA) beam -- (ref.: BNL-E889 Proposal)  Target Horns Decay Pipe Far Det. Decay Kinematics  Increase statistics @ osc. max.  Decrease background from HE tail 1/~1/~ E  (GeV) E (GeV) 5 1 2  flux

29.    flux for CPV meas. -15%@peak   10 21 POT/yr Sign flip by just changing horn plarity Example 50GeV proton At 295km

30. Cross sections  Cross section ∝ E  Higher energy  higher statistics  Anti-neutrino cross section smaller than neutrino by ~1/3  Why?  Take ~3 times more time for anti-neutrino measurements to acquire same statistics as neutrino

31. 31  e 00 Back ground for e appearance search Intrinsic e component in initial beam Merged  0 ring from  interactions e appearance search e appearance search

32. “Available” technologies for huge detector Liq Ar TPC  Aim O(100kton)  Electronic “bubble chamber”  Can track every charged particle  Down to very low energy  Neutrino energy reconstruction by eg. total energy  No need to assume process type  Capable upto high energy  Good PID w/ dE/dx, pi0 rejection  Realized O(1kton) Water Cherenkov  Aim O(1000kton)  Energy reconstruction assuming Ccqe  Effective < 1GeV  Good PID (  /e) at low energy  Cherenkov threshold  Realized 50kton 32 Good at Wideband beam Good at low E (<1GeV) narrow band beam

33. Neutrino Energy  reconstruction in Water Cherenkov CC quasi elastic reaction  + n →  + p -- p (E , p  )  QE inelastic  + n →  + p +  -- p (E , p  )   

34. 2 approaches for CPV (and sign(  m 2 ) )  Energy spectrum measurement of appeared e  Only w/ numu beam (at least early part)  Measure term ∝ cos  (and sin  )  Assume standard source of CPV (  in MNS)  Cover 2 nd oscillation maximum (higher sensitivity on CPV)  Higher energy = longer baseline favorable  Wideband beam suited  Liq Ar TPC is better suited  Difference between P(numu  nue) and P(numubar  nuebar)  Measure term ∝ sin   Not rely on the standard scenario 34

35. Angle and Baseline OA3° OA0° OA2° OA2.5°  flux Off-axis angle – On-Axis: Wide Energy Coverage, ○ Energy Spectrum Measurement ×Control of π 0 Background – Off-Axis: Narrow Energy Coverage, ○ Control of π 0 Background ×Energy Spectrum Measurement → Counting Experiment Baseline – Long: ○ 2 nd Osc. Max. at Measurable Energy × Less Statistics ? Large Matter Effect – Short: ○ High Statistics × 2 nd Osc.Max.Too Low Energy to Measure ? Less Matter Effect (E/L)  CP =90  CP =270  CP =0  m 31 2 = 2.5x10 -3 eV 2 sin 2 2  13 = 0.1 No matter effects ν μ  ν e oscillation probability Oscillation probability 35

36. “Available” beams 36

37. 37

38. FNAL possible future Plan 38

39. CERN future possibilities 39 Present accelerator complex Various POSSIBLE scenarios  Under discussion

40. CERN possibilities 40

41. Okinoshima 658km 0.8deg. Off-axis Kamioka Korea 1000km 1deg. Off-axis 295km 2.5deg. Off-axis Possible scenarios in Japan 41

42. Okinoshima 658km 0.8deg. Off-axis Cover 1 st and 2 nd Maximum Neutrino Run Only 5Years×1.66MW 100kt Liq. Ar TPC -Good Energy Resolution -Good e/π ０ discrimination Keeping Reasonable Statistics Scenario 1 δ=0° ν e Spectrum Beam ν e Background CP Measurement Potential NP08, arXiv:0804.2111 δ=90° δ=180°δ=270° sin 2 2θ 13 =0.03,Normal Hierarchy  42

43. 295km 2.5deg. Off-axis ~0.6GeV Tokai Kamioka Cover 1 st Maximum Only 2.2Years Neutrino+7.8Years anti-Neutrino Run 1.66MW 540kt Water Cherenkov Detector Scenario 2 K.Kaneyuki @NP08    =0  =  /2 E r ec  +  BG  +  e  e BG signal+BG sin 2 2θ 13 =0.03,Normal Hierarchy sin 2 2  13 Fraction of   CP sensitivity sin 2 2θ 13 deg. 43

44. Site studies in Europe 44

45. 45

46. US Superbeam Strategy: Young-Kee Kim, Oct. 1-3, 2009 NSF’s proposed Underground Lab. DUSEL 1300 km Project X: ~2 MW 700kW 15kt Liquid Scintillator Under construction NOvA ~50 kton Liquid Ar TPC ~300 kton Water Cerenkov MiniBooNE SciBooNE MINOS NOvA MINERvA MicroBooNE 735 km 2.5 msec 810 km Combination of WC and LAr FNAL possibilities

47. FNAL-DUSEL potential

48. To realize the experiments Need  Finite (reasonable)  13  T2K, NOvA, Reactors!  High power (>MW) neutrino beam  Huge high-sensitivity detector   YOUR CHALLENGE  OR YOUR NEW IDEA! 48

49. Summary  Properties of neutrino are gradually being revealed  However still yet far unknown than quarks  CPV, mass hierarchy, etc.  Especially, CP symmetry could be a critical key to answer the fundamental question: What is the origin of matter in the universe  Future superbeam long baseline oscillation experiments have chance to discover CPV effect (if  13 is large enough to be detected in present on-going experiments)  Already many studies and developments (beam, detectors) are being made around the world to realize the experiments  Lot’s of challenges and funs forseen  Let’s enjoy! 49

50. 1000km 1deg. Off-axis 295km 2.5deg. Off-axis Scenario 3 Cover 2 nd Maximum @ Korea Cover 1 st Maximum @ Kamioka 5Years ν+5Years ν Run 1.66MW 270kt Water Cherenkov Detector each @ Korea, Kamioka F.Dufour@NP08 (study is initiated by M.Ishitsuka et. al. hep-ph/0504026) 50

51. Comparison of Each Scenario Scenario 1 Okinoshima Scenario 2 Kamioka Scenario 3 Kamioka Korea Baseline(km)660295295 & 1000 Off-Axis Angle(°)0.8(almost on-axis)2.52.5 1 Methodν e Spectrum ShapeRatio between ν e ν e Ratio between 1 st 2 nd Max Ratio between ν e ν e Beam5Years ν μ, then Decide Next 2.2 Years ν μ, 7.8 Years ν μ, 5 Years ν μ, Detector Tech.Liq. Ar TPCWater Cherenkov Detector Mass (kt)1002×270270+270 51

52. Additional requirement for far detector optimization Proton Decay Discovery Performance Realization of the huge detector – Test of the key components – Experimentally prove the detector performance if necessary, good prototyping (able to predict Huge Detector Performance well) is important Test with the beam is important KEK started R&D for Huge Liq. Ar TPC with ETH Zurich 52  See Maruyama’s talk

53. 53 Constraints on  m 12 2,  12 太陽＆原子炉ニュートリノ

54. 54 K2K(1999~2004) 735km MINOS(2005~)  23,  m 23 2 : 大気ニュートリノと加速器実験 SK(1996~) すべて “ 消失 ” 実験 M.Diwan, Venice, Mar.2009      m 23 2  eV 

55. 55  13 の上限値 原子炉反電子ニュートリノ消失実験 Chooz

56. If neutrinos have mass: ~0.03  /4 And sin 2 2  13 < ~0.14 Three neutrino mixing.

57. T.Kobayashi (KEK) 57  13 の測り方 加速器ニュートリノによる  13 ミューニュートリノ： ~ O(GeV)  e 出現実験 P(   e ) = sin 2  23 ・ sin 2 2  13 ・ sin 2 (1.27  m 2 31 L/E) + many terms (incl.  )  Appearance measurement  統計 ( ＝ビームパワーｘ検出器サイズ ) 勝負 原子炉ニュートリノによる  13 反電子ニュートリノ： ~ a few MeV  e 消失実験 P( e  e ) = 1- sin 2 2  13 ・ sin 2 (1.27  m 2 31 L/E) + O(  m 2 21 /  m 2 31 ) pure  13  Almost pure measurement of  13. 消失信号が小さい  系統誤差勝負

58. 58 Takashi Kobayashi (KEK), PAC07 58 mass m1m1 m2m2  Neutrino Mixing L:flight dist 、 E :neutrino energy Neutrino Oscillation (in 2flavor approx.) 1-P(    ) L=250km,  m 23 2 =3x10 -3 eV 2 1 2 Weak eigenstatesMass eigenstates sin 2 2  m2m2 現象  元の種類のニュートリノが減 少 ( “ Disappearance ” )  別の種類のニュートリノが出 現 ( “ Appearance ” )  振動に特徴的なエネルギー分 布 Disappearance ( 消失 )  Probability to change flavor sin 2 2  m2m2 Appearance ( 出現 ) E (GeV)

59. Long baseline osc. experiments  1 st phase experiments (Now)  Confirmation of atm. results  K2K(1999~)/MINOS(2005~)/ICARUS/OPERA(2006~)  2 nd phase experiments (Now~10yrs)  Discovery of e appearance  Designed & Optimized aft. SK atm  ~MW beam w/ ~50kton detector  T2K-I (approved. 2009~)/NO A (2009?~) / (C2GT)  3 rd phase experiments(10~20yrs?)  CP violation and mass hierarchy thru   e app.  Typically Multi-MW beam & Mton detector  2 nd phase is critical step to go 59 Classification by G.Feldman @SB WS@BNL “ Super Beam ” Experiments ()() ()()

60. Quest for the Origin of Matter Dominated Universe One of the Main Subject of the KEK Roadmap Discovery of Lepton CP Violation Proton Decay Discovery of the e Appearance Neutrino Intensity Improvement Huge Detector R&D T2K (2009~) Water Cherenkov v Liquid Ar TPC Establish Huge Detector Technology Construction of Huge Detector

61. Accelerator Based Neutrino Project in Japan K2KT2K3 rd Generation Exp. (KEK Roadmap) High Power Proton Synchrotron KEK PS 12GeV 0.005MW Existing J-PARC MR 30GeV up to 0.75MW Brand New J-PARC MR 30GeV 1.66MW Technically Feasible Upgrade Neutrino BeamlineK2K Neutrino Beamline Brand New J-PARC Neutrino Beamline Brand New J-PARC Neutrino Beamline Existing Far DetectorSuper Kamiokande Existing at KAMIOKA Super Kamiokande Existing at KAMIOKA Brand New -Detector Technology ? -Place ? (Angle and BaseLine) 1 st Priority Physics Case Neutrino Oscillation ν μ Disappearance Neutrino Oscillation ν μ  ν e Lepton Sector CP Violation + Proton Decay Search Able to concentrate on Far Detector issue toward the 3 rd Generation Experiment after T2K startup 61