1. Takaaki Kajita ICRR, Univ. of Tokyo KIAS, Seoul, Nov. 2005 Fig: Senda NP-4

2. Non-LBL physics with large water Cherenkov detectors Atmospheric neutrinos (300 events /day) Proton decay Supernova neutrinos (200,000 events for SN @galactic center) Supernova relic neutrinos Solar neutrinos (300-400 events/day) ……

3. Outline Assumptions Neutrino oscillation physics with atmospheric neutrinos Proton decay Comment on photo cathode coverage Summary Apology: references incomplete…

4. Assumptions JPARC Fig: Talk by K.Senda @NP04 (also, hep-ph/0504061) Off-axis angle Distance from the target (km) 1)Fid. Mass Kamioka+Korea =0.54 Mton 2)Detector performance = Super-K 1)Fid. Mass Kamioka+Korea =0.54 Mton 2)Detector performance = Super-K

5. Neutrino oscillation physics with atmospheric neutrinos TK NNN05

6. e     3 2 1 Solar, KamLAND Solar, KamLAND Atmospheric Long baseline Atmospheric Long baseline  12,  m 12 2 mass and mixing parameters:  12,  23,  13, ,  m 12 2,  m 13 2 (=  m 23 2 ) Known:  23, |  m 23 2 | KamLAND SNO(+Super-K) Super-K K2K Reactor solar atmospheric long baseline

7. mass and mixing parameters:  12,  23,  13, ,  m 12 2,  m 13 2 (=  m 23 2 ) Unknown:   13 Sign of  m 23 2 or CP ? Future long baseline eperiments  JPARC-Kamioka-Korea (Atmospheric neutrino exp.s could help….) 3 2 1 e     If  23 ≠  /4, is it >  /4 or <  /4 ? 3 or e     Atmospheric neutrino experiments Near future reactor, LBL exp’s 3

8. s 2 2  12 =0.825  m 2 12 =8.3×10 -5  m 2 23 =2.5×10 -3 sin 2  13 =0 Because of the LMA solution, atmospheric neutrinos should also oscillate by (  12,  m 12 2 ). Oscillation probability is different between s 2  23 =0.4 and 0.6  discrimination between  23 >  /4 and <  /4 might be possible. However, due to the cancellation between   e and e  , the change in the e flux is small. Peres & Smirnov NPB 680 (2004) 479 Solar term effect to atmospheric Solar term effect to atmospheric

9. Effect of the solar term to sub-GeV e-like zenith angle sub-GeV e-like  m 2 12 = 8.3 x 10 -5 eV 2  m 2 23 = 2.5 x 10 -3 eV 2 sin 2 2  12 = 0.82 sin 2  13 =0 sin 2  23 = 0.4 sin 2  23 = 0.5 sin 2  23 = 0.6 (P e :100 ~ 1330 MeV)(P e :100 ~ 400 MeV)(P e :400 ~ 1330 MeV) cos  zenith e-like (3 flavor) / e-like (2 flavor full-mixing) (Much smaller and opposite effect for  -like events.)  /e ratio @low energy is useful to discriminate  23 >  /4 and <  /4.

10. Effect of the solar terms to the sub-GeV  /e ratio (zenith angle dependence) sub-GeVP , e < 400 MeVP , e > 400 MeV  m 2 12 = 8.3 x 10 -5 eV 2  m 2 23 = 2.5 x 10 -3 eV 2 sin 2 2  12 = 0.82 sin 2  13 =0 (  e) (3 flavor) (  e) (2 flavor full-mixing) sin 2  23 = 0.6 sin 2  23 = 0.4 sin 2  23 = 0.5 2 flavor (sin 2 2  23 =.96) It could be possible to discriminate the octant of  23, if sin 2  23 is significantly away from 0.5.

11. Expected oscillation with solar terms (2) s 2 2  12 =0.825  m 2 12 =8.3×10 -5  m 2 23 =2.5×10 -3 s 2  23 =0.4 s 2  13 =0.0 Effect of LMA s 2  23 =0.4 s 2  13 =0.04  cp =  /4 Effect of  13 Interference (CP) = 1 + P 2 (r cos 2  23 – 1) P 2 = 2 transition probability e   in matter driven by  m 12 2 In addition, we may have non-zero  13.

12. Search for non-zero  13 (  m 12 2 =0 assumed) E (GeV) cos  zenith Matter effect s 2 13=0.05 s 2 13=0.00 null oscillation Electron appearance 1+multi-ring, e-like, 2.5 - 5 GeV 0.45Mtonyr cos  0.45 Mtonyr 33 Approximate CHOOZ bound

13. Binning for this study (= osc. analysis in SK) E Single- Ring  Multi- Ring  Up-stop Up-through 37 momentum bins x 10 zenith bins = 370 bins in total Multi- Ring e Single- Ring e PC- stop PC- through 10 zenith angle bins for each box. Small number of events per bin Poisson statistics to claculate  2 with 45 systematic error terms Multi- GeV Sub- GeV CC e CC  For more details: please ask H.K.Seo and S.Nakayama

14. 0.092 Mtonyr Super-K data Analysis with and w/o solar terms with 12 terns (best fit s 2  23 = 0.51) w/o 12 3 2 1 sin 2  23 sin 2  13 Search for non-zero  13 E (GeV) cos  zenit h

15. Discrimination between  23 >  /4 and  /4 and <  /4 with the (12) and (13) terms s 2  23 =0.40 ~ 0.60 s 2  13 =0.00~0.04  cp=45 o Discrimination between  23 >  /4 and <  /4 is possible for all  13. 1.8Mtonyr (or 3.3yr×0.54Mton) Discrimination between  23 >  /4 and 0.04. sin 2  23 sin 2  13 sin 2 2  23 =0.96sin 2 2  23 =0.99 90%CL Test point Fit result M.Shiozawa et al, RCCN Int. Workshop on sub-dom. Atm. Osc. 2004

16. Improvement possible ?  m 2 12 = 8.3 x 10 -5 eV 2  m 2 23 = 2.5 x 10 -3 eV 2 sin 2 2  12 = 0.82 sin 2  13 =0 P , e < 400 MeV sin 2  23 = 0.6 sin 2  23 = 0.4 sin 2  23 = 0.5 2 flavor (sin 2 2  23 =.96) (  e) (3 flavor) (  e) (2 flavor full-mixing) true 0.8 Mtonyr = SK 20yr = HK 0.8yr S.Nakayama, RCCN Int. Workshop on sub-dom. Atm. Osc. 2004

17. Search for proton decay Lifetime in benchmark scenarios J.Ellis NNN05 C.K.Jung NNN05 How long is the predicted proton lifetime ? SK limit (e  0 ) SK limit ( K + )

18. Search for p  e +  0 P tot < 250 MeV/c, BG 2.2ev/Mtyr, eff=40% P tot < 100 MeV/c, BG 0.15ev/Mtyr, eff=17% Atm 20Mtonyr free proton decay bound proton decay Main target is free proton decays for the tight cut. p  e  0 Monte Carlo e+e+ e+e+  0   M.Shiozawa NNN05 Now (near future) Future

19. Lifetime sensitivity for p  e +  0 Normal cut, 90%CL 3  CL Tight cut, 90%CL 3  CL p  e+  0 sensitivity 5Mtonyrs  ~10 35 years@90%CL ~4x10 34 years@3  CL 5Mtonyrs

20. p  K + O  , K + →   (1) 16 O  K +15 N , K + →   e + 236MeV/c 6 – 10 MeV Signal region Background = 0.7  = 8.6% Candidate = 0 N PMT-hit distribution for the prompt gamma search (Also, searches for (2) p  K + (K +   +  0 ) (3) P  K + (K +   +, without  ) )

21. νK + sensitivity (based on SK criteria) τ/B > 2 × 10 34 yr (5Mtonyr, 90%CL) Question: How much photo cathode coverage is necessary? Most updated number = 2,3×10 33 yrs 5Mtonyrs 12nsec 2.2  sec

22. Photo cathode coverage ? Cost for the photo-detectors is a significant part of the total detector cost. If 40% coverage with 50cm diameter PMT’s for 0.27 Mton fiducial mass;  100,000 PMT’s.  If 100 (200?) $ / PMT  100M$ (200?M$) Important to understand minimum requirement of photo- coverage from each physics topics SK-II (19% coverage  SK-I 40%) is a good opportunity to investigate physics sensitivity with reduced photo- coverage.  LBL physics  Atmospheric neutrinos  Proton decay (e  0 )  This talk  Proton decay ( K + )  Astrophysical neutrinos (SN, solar neutrinos?...)

23. Proton mass vs. momentum SK-I  =40.1% SK-I 8 /2.2Mtyr SK-II 2 /0.45Mtyr SK-II  =41.1% atm (BG) MC p  e  0 MC

24. Proton mass and momentum SK-I SK-II p  e  0 MC p mom. resolution; 177MeV(68%)  171 ( free proton) 81MeV(68%)  83 p mom. resolution; 177MeV(68%)  171 ( free proton) 81MeV(68%)  83 p mass resolution; 33.8MeV  42.3 (free proton) 28.5MeV  35.2 p mass resolution; 33.8MeV  42.3 (free proton) 28.5MeV  35.2  p  e  0 looks OK with 20% photo cathode coverage.

25. Photo cathode coverage ?  LBL physics Need careful checks  Atmospheric neutrinos  20% probably OK. (No proof today…)  Proton decay (e  0 )  20% looks OK.  Proton decay ( K + ) We will know in a month or half a year…  Astrophysical neutrinos (SN, solar ?...) Need checks…

26. Mton class water detectors will have a lot of physics opportunities. Mton class detectors can not be cheap. Therefore it is very nice that it could carry out many important physics.

27. End

28. Solar neutrino physics with Mton detectors Solar global KamLAND Solar+KamLAND 95% 99.73% P( e  e ) Vacuum osc. dominant matter osc. (MeV) Do we want further evidence for matter effect ? M.Nakahata NNN05 Day-night asymmetry

29. Expected signal 8 B spectrum distortion Enough statistics to see distortion. Energy scale calibration should be better than ~0.3%. E e (MeV) Data/SSM 5 Mton·years Correlated sys. error of SK sin 2  =0.28,  m 2 =8.3×10 -5 eV 2 1/2 of SK Day-night stat. significance 3  signal can be obtained with 0.5% day-night systematic error. In both cases, systematic errors or background are assumed to be better than SK.

30. Supernova events in a Mega-ton detector A.Dighe NNN05 Number of anti- e +p interactions = 200,000 - 300,000 for a galactic Supernova (@10kpc) ◆ Initial spectra rather poorly known. ◆ Only anti- e observed  Difficult find a “clean” observable, which is (almost) independent of the assumptions on the initial spectra. ◆ Initial spectra rather poorly known. ◆ Only anti- e observed  Difficult find a “clean” observable, which is (almost) independent of the assumptions on the initial spectra.

31. Supernova shock and neutrino oscillations Assume: nature = inverted hierarchy Anti- e If sudden change in the average energy is observed  Inverted mass hierarchy and sin 2  13 >10 -5. sin 2  13 Forward shock Reverse shock  m 13 2 resonance  m 12 2 resonance A.Dighe NNN05 R.Tomas et al., astro-ph/0407132

32. Mton is large: The detectors can see extragalactic SNe Nearby SN rate SK HK Detection probability S.Ando NNN05

33. Supernova relic neutrinos (SRN) SRN prediction SK result e +anti- e Invisible   e SNR limit 90%CL 90%CL limit: 1.2 /cm 2 /sec (E >19MeV) (which is just above the most recent prediction 1.1/cm 2 /sec)  get information on galaxy evolution and cosmic star formation rate With a Mton detector, it must be possible to see SRN signal S.Ando, M.Nakahata NNN05

34. Mton detector with Gd loaded water GADZOOKS! M.Vagins NNN05 B.G. reduction by neutron tagging No neutron tagging Statistically 4.6  excess (E vis > 15 MeV) Simulation: M.Nakahta NNN05 (0.2% GdCl 3 ) M.Vagins, J.Beacom hep-ph/0309300 Invisible   e

35. End

36. 45 systematic error terms (0, Free parameter) Flux, Nu-int, Fit; absolute normalization (1) Flux; (nu_mu + anti-nu_mu) / (nu_e + anti-nu_e) ratio ( E_nu < 5GeV ) (2) Flux; (nu_mu + anti-nu_mu) / (nu_e + anti-nu_e) ratio ( E_nu > 5GeV ) (3) Flux; anti-nu_e / nu_e ratio ( E_nu < 10GeV ) (4) Flux; anti-nu_e / nu_e ratio ( E_nu > 10GeV ) (5) Flux; anti-nu_mu / nu_mu ratio ( E_nu < 10GeV ) (6) Flux; anti-nu_mu / nu_mu ratio ( E_nu > 10GeV ) (7) Flux; up/down ratio (8) Flux; horizontal/vertical ratio (9) Flux; K/pi ratio (10) flight length of neutrinos (11) spectral index of primary cosmic ray above 100GeV (12) sample-by-sample relative normalization ( FC Multi-GeV ) (13) sample-by-sample relative normalization ( PC + Up-stop mu ) (14) M A in QE and single-  (15) QE models (Fermi-gas vs. Oset's) (16) QE cross-section (17) Single-meson cross-section (18) DIS models (GRV vs. Bodek's model) (19) DIS cross-section (20) Coherent-  cross-section (21) NC/CC ratio (22) nuclear effect in 16 O (23) pion spectrum (24) CC   cross-section (25) Reduction for FC (26) Reduction for PC (27) Reduction for upward-going muon (28) FC/PC separation (29) Hadron simulation (contamination of NC in 1-ring  -like) (30) Non- BG ( flasher for e-like ) (31) Non- BG ( cosmic ray muon for mu-like ) (32) Upward stopping/through-going mu separation (33) Ring separation (34) Particle identification for 1-ring samples (35) Particle identification for multi-ring samples (36) Energy calibration (37) Energy cut for upward stopping muon (38) Up/down symmetry of energy calibration (39) BG subtraction of up through  (40) BG subtraction of up stop  (41) Non- e contamination for multi-GeV 1-ring electron (42) Non- e contamination for multi-GeV multi-ring electron (43) Normalization of multi-GeV multi-ring electron (44) PC stop/through separation Flux (13) interaction (11) Detector, reduction and reconstruction (20) Detector, reduction and reconstruction (20)

37. sub-GeV  -like zenith angle sub-GeV  -like (P  : 200 ~ 1330 MeV)  m 2 12 = 8.3 x 10 -5 eV 2  m 2 23 = 2.5 x 10 -3 eV 2 sin 2 2  12 = 0.82 sin 2  23 = 0.4 sin 2  23 = 0.5 sin 2  23 = 0.6 2 flavor (sin 2 2  23 = 0.96) X : zenith angle Y : N_  (3 flavor) / N_  (2 flavor full-mixing) (P  : 200 ~ 400 MeV)(P  : 400 ~ 1330 MeV)

38. Discrimination between  23 >  /4 and  /4 and <  /4 with the (12) and (13) terms s 2  23 =0.40 ~ 0.60 s 2  13 =0.00~0.04  cp=45 o Discrimination between  23 >  /4 and <  /4 is possible for all  13. 1.8Mtonyr = SK 80 yrs = 3.3 HK yrs Discrimination between  23 >  /4 and 0.04. sin 2  23 sin 2  13 sin 2 2  23 =0.96sin 2 2  23 =0.99 90%CL Test point Fit result