March 6 th 2005 XLth Rencontres de Moriond

March 6 th, 2005 @XLth Rencontres de Moriond C. Mariani (INFN Rome) for K 2 K collaboration C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

K 2 K Collaboration 250 km JAPAN: High Energy Accelerator Research Organization (KEK) / Institute for Cosmic Ray Research (ICRR), Univ. of Tokyo / Kobe University / Kyoto University / Niigata University / Okayama University / Tokyo University of Science / Tohoku University KOREA: Chonnam National University / Dongshin University / Korea University / Seoul National University U. S. A. : Boston University / University of California, Irvine / University of Hawaii, Manoa / Massachusetts Institute of Technology / State University of New York at Stony Brook / University of Washington at Seattle POLAND: Warsaw University / Solton Institute Since 2002 JAPAN: Hiroshima University / Osaka University U. S. A. : Duke University CANADA: TRIUMF / University of British Columbia ITALY: Rome FRANCE: Saclay SPAIN: Barcelona / Valencia SWITZERLAND: Geneva RUSSIA: INR-Moscow C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

1. Introduction and history of K 2 K p p p 1995 n Proposed to study neutrino oscillation for atmospheric neutrinos anomaly. 1999 n Started taking data. 2000 n Detected smaller number of neutrinos than the expectation at a distance of 250 km. Disfavored null oscillation at the 2 s level. 2002 n Observed indications of neutrino oscillation. The probability of null oscillation is less than 1%. 2004 n Confirm neutrino oscillation with both a deficit of nm and the distortion of the En spectrum. C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

2. K 2 K experiment ~1 event/2 days ~1011 nm/2. 2 sec (/10 m 10 m) 12 Ge. V protons p+ ~106 nm/2. 2 sec nm (/40 m 40 m) SK nt m+ Target+Horn p monitor 200 m decay pipe m monitor 100 m ~250 km Near n detectors (ND) (monitor the beam center) Signal of n oscillation at K 2 K Reduction of nm events l Distortion of nm energy spectrum l C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Neutrino beam and the directional control ~1 Ge. V neutrino beam by a dual horn system with 250 k. A. < 1 mrad C. Mariani@XLth Rencontres de Moriond (6 th March 2005) ~5 years Y center ≤ 1 mrad X center The beam direction monitored by muons

Accumulated POT (Protons On Target) protons/pulse Accumulated POT (× 1018) (× 1012) 10. 5 x 1019 POT, 8. 9× 1019 POT for Analysis K 2 K-II Jan 03 C. Mariani@XLth Rencontres de Moriond (6 th March 2005) Oct-Nov 04

Neutrino spectrum and the far/near ratio n beam 250 km Far/Near Ratio nm energy spectrum @ K 2 K near detector beam MC w/ PION Monitor 10 -6 En (Ge. V) C. Mariani@XLth Rencontres de Moriond (6 th March 2005) 1. 0 2. 0 En (Ge. V)

GPS SK Events Tspill TOF=0. 83 msec SK TSK Decay electron cut. 500 msec 20 Me. V Deposited Energy No Activity in Outer Detector Event Vertex in Fiducial Volume More than 30 Me. V Deposited Energy 107 events 5 msec Analysis Time Window -0. 2<TSK-Tspill-TOF<1. 3 msec (BG: 1. 6 events within 500 ms 2. 4× 10 -3 events in 1. 5 ms) C. Mariani@XLth Rencontres de Moriond (6 th March 2005) TDIFF. (ms)

3. Analysis Overview KEK Observation #n, pm and qm Measurement F(En), n interaction MC Far/Near Ratio (beam MC with p mon. ) SK Observation #n and En rec. C. Mariani@XLth Rencontres de Moriond (6 th March 2005) (sin 22 q, Dm 2) Expectation #n and En rec.

NEUT: K 2 K Neutrino interaction MC p CC quasi elastic (CCQE) v CC (resonant) single p(CC 1 p) p p DIS NC s/E (10 -38 cm 2/Ge. V) Total (NC+CC) CC Total CC quasi-elastic DIS CC single p NC single p 0 En (Ge. V) C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

4. Near detector measurements p p p 1 KT Water Cherenkov Detector (1 KT) Scintillating-fiber/Water sandwich Detector (Sci. Fi) Lead Glass calorimeter (LG) before 2002 Scintillators Bar Detector (Sci. Bar) after 2003 Muon Range Detector (MRD) LG calorimeter Muon range detector C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

4. 1 1 KT Flux measurement p p The same detector technology as Super-K. Sensitive to low energy neutrinos. Far/Near Ratio (by MC)~1× 10 -6 M: Fiducial mass e: efficiency N exp SK MSK=22, 500 Kton, e. SK-I(II)=77. 0(78. 2)%, =150. 9 C. Mariani@XLth Rencontres de Moriond (6 th March 2005) +12 -10 N obs SK MKT=25 ton e. KT=74. 5% =107

4. 2 Sci. Bar neutrino interaction study p Full Active Fine-Grained detector (target: CH). n n Sensitive to a low momentum track. Identify CCQE events and other interactions (non-QE) separately. CCQE Candidate n CCQE p m 25 C. Mariani@XLth Rencontres de Moriond March 2005) non-QE DATA CC QE CC 1 p CC coherent-p CC multi-p Dqp =qobs -q. CCQE (6 th 2 track events Dqp (degree)

Neutrino energy reconstruction C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

A hint of K 2 K forward m deficit. K 2 K observed forward m deficit. n n A source is non-QE events. For CC-1 p, p Suppression of ~q 2/0. 1[Ge. V 2] at q 2<0. 1[Ge. V 2] may exist. (0. 1 Ge. V 2 value comes from fitting 2 track non. QE sample in Sci. Bar) n For CC-coherent p, p The coherent p may not exist. We do not identify which process causes the effect. The MC CC-1 p (coherent p) model is corrected phenomenologically. Oscillation analysis is insensitive to the choice. C. Mariani@XLth Rencontres de Moriond (6 th March 2005) q 2 rec Preliminary DATA CC 1 p CC coherent-p q 2 rec (Ge. V/c)2 (Data-MC)/MC Sci. Bar non-QE Events q 2 rec (Ge. V/c)2

4. 3 Near Detector Spectrum Measurements p 1 KT n p Sci. Bar n p Fully Contained 1 ring m (FC 1 Rm) sample. 1 track, 2 track QE (Dqp≤ 25 ), 2 track n. QE (Dqp>25 ) where one track is m. Sci. Fi n 1 track, 2 track QE (Dqp≤ 25 ), 2 track n. QE (Dqp>30 ) where one track is m. After applying the low q 2 suppression of n. QE observed in Sci. Bar, the angular distributions of all other samples are reasonably reproduced. C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

1 KT: m momentum and angular distributions. with measured spectrum flux measurement low q 2 corr. 800 0 1600 pm (Me. V/c) 1 Kt m-like sample Quasi elastic Single pion C. Mariani@XLth Rencontres de Moriond (6 th March 2005) 0 20 qm (deg. ) 90

4. 4 Near Detectors combined measurements (pm, qm) for 1 track, 2 track. QE and 2 track n. QE samples F(En), n. QE/QE p p Fitting parameters n F(En), n. QE/QE ratio n Detector uncertainties on the energy scale and the track counting efficiency. n The change of track counting efficiency by nuclear effect uncertainties; proton re-scattering and p interactions in a nucleus … Strategy ① Measure F(En) in the more relevant region of qm 20 for 1 KT and qm 10 for Sci. Fi and Sci. Bar. ② Apply a low q 2 correction factor to the CC-1 p model (or coherent p). ③ Measure n. QE/QE ratio for the entire qm range. C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

qm (Me. V/c) En KT data 0 -0. 5 Ge. V 0. 5 -0. 75 Ge. V 0. 75 -1. 0 Ge. V Pm (Me. V/c) • n flux FKEK(En) (8 bins) • n interaction (n. QE/QE) C. Mariani@XLth Rencontres de Moriond (6 th March 2005) 1. 0 -1. 5 Ge. V QE (MC) n. QE(MC) MC templates

Flux measurements c 2=638. 1 for 609 d. o. f n n n n n F 1 ( En < 500) = 0. 78 0. 36 F 2 ( 500 En < 750) = 1. 01 0. 09 F 3 ( 750 En <1000) = 1. 12 0. 07 F 4 (1000 En <1500) = 1. 00 F 5 (1500 En <2000) = 0. 90 0. 04 F 6 (2000 En <2500) = 1. 07 0. 06 F 7 (2500 En <3000) = 1. 33 0. 17 F 8 (3000 En ) = 1. 04 0. 18 n. QE/QE = 1. 02 0. 10 The n. QE/QE error of 10% is assigned based on the sensitivity of the fitted non. QE/QE value by varying the fit criteria. p q>10 (20 ) cut: n. QE/QE=0. 95 0. 04 p standard(CC-1 p low q 2 corr. ): n. QE/QE=1. 02 0. 03 p No coherent: p=n. QE/QE=1. 06 0. 03 C. Mariani@XLth Rencontres de Moriond (6 th March 2005) F(En) at KEK preliminary En

Sci. Fi (K 2 K-IIa with measured spectrum) qm 1 trk Pm 1 trk flux measurement 0 C. Mariani@XLth Rencontres de Moriond (6 th March 2005) Pm 2 trk QE qm 2 trk QE Pm 2 trk non-QE qm 2 trk non-QE 2 (Ge. V/c) 0 10 40 (degree)

Sci. Bar (with measured flux) qm 1 trk Pm 1 trk flux measurement Pm 2 trk QE qm 2 trk n. QE Pm 2 trk n. QE C. Mariani@XLth Rencontres de Moriond (6 th March 2005) 10

5. Super-K oscillation analysis p p p Total Number of events Enrec spectrum shape of FC-1 ring-m events Systematic error term f x : Systematic error parameters Normalization, Flux, and n. QE/QE ratio are in fx Near Detector measurements, Pion Monitor constraint, beam MC estimation, and Super. K systematic uncertainties. C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

K 2 K-SK events K 2 K-all (K 2 K-I, K 2 K-II) FC 22. 5 k. T DATA (K 2 K-I, K 2 K-II) 107 (55, 52) 1 ring 67 (33, 34) m-like 57 (56) (30, 27) for Enrec e-like 10 (3, 7) Multi Ring 40 (22, 18) *Updated C. Mariani@XLth Rencontres de Moriond (6 th March 2005) MC (K 2 K-I, K 2 K-II) 150. 9 (79. 1*, 71. 8) 93. 7 (48. 6, 45. 1 ) 84. 8 (44. 3, 40. 5) 8. 8 (4. 3, 4. 5) 57. 2 (30. 5, 26. 7) from the previous analysis

KS probability=0. 08% #SK Events Toy MC Expected shape (No Oscillation) CC-QE assumption 107 Enrec[Ge. V] 150. 9 C. Mariani@XLth Rencontres de Moriond (6 th March 2005) V: Nuclear potential

6. Results p Dm 2 p Best fit values. n sin 22 q = 1. 51 n Dm 2 [e. V 2] = 2. 19 10 -3 Best fit values in the physical region. n sin 22 q = 1. 00 A toy MC n Dm 2 [e. V 2] = 2. 79 10 -3 Dlog. L=0. 75 2. 79 sin 22 q=1. 51 can occur due to a a statistical fluctuation with 12. 6%. C. Mariani@XLth Rencontres de Moriond (6 th March 2005) 12. 6% 1. 00 1. 51 sin 22 q

Data are consistent with the oscillation. Dm 2[e. V 2] p preliminary p NSKobs=107 NSKexp (best fit)=150. 9 Best Fit KS prob. =36% sin 22 q Based on Dln. L C. Mariani@XLth Rencontres de Moriond (6 th March 2005) Enrec[Ge. V]

Log Likelihood difference from the minimum. Dln. L - 68% - 90% - 99% Dm 2[e. V 2] p C. Mariani@XLth Rencontres de Moriond (6 th March 2005) - 68% - 90% - 99% sin 22 q Dm 2<(1. 87~3. 58)× 10 -3 e. V 2 at sin 22 q=1. 0 (90% C. L. )

nm disappearance versus En shape distortion En shape Dm 2[e. V 2] NSK (#nm) sin 22 q Both disappearance of nm and the distortion of En spectrum have the consistent result. C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

K 2 K-I vs K 2 K-II C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Null oscillation probability The null oscillation probabilities are calculated based on Dln. L. K 2 K-I nm disappearance K 2 K-II K 2 K-all 2. 0% 3. 7% 0. 26%(3. 0 s) En spectrum distortion 19. 5% 5. 4% 0. 74% (2. 6 s) Combined 1. 3%* 0. 56% 0. 0050% (2. 5 s) (2. 8 s) (4. 0 s) *: The value is changed from the previous one. Disappearance of nm and distortion of the energy spectrum as expected in neutrino oscillation. K 2 K confirms neutrino oscillation discovered in Super-K atmospheric neutrinos. C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

8. Summary p With 8. 9 1019 POT, K 2 K has confirmed neutrino oscillations at 4. 0 s (hep-ex/0411038) n Disappearance of nm 3. 0 s n Distortion of En spectrum 2. 6 s Dm 2[e. V 2] 0. 006 K 2 K new results 0. 004 - 68% - 90% - 99% preliminary 0. 002 0. 0 0. 2 0. 4 0. 6 0. 8 1. 0 sin 22 q C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Backup slide C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Additional Error on non. QE p non. QE value depends on fitting condition. n n p Small angle cut: 0. 979 8% CC 1 p re-weighting: 1. 056 Official value No coherent p: 1. 093 3. 5% CC 1 p re-weighting factor +/– 0. 03 (1 s) (Sci. Bar only fit): +/– 4% In total, ~10% uncertainty exists. n Fitting error is ~5% add 10% to non. QE error. C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

7. Other Physics in K 2 K (K 2 K-I data only) nm +H 2 O NC 1 p 0 1 KT Mgg(Me. V) =0. 065 0. 001 0. 007 =0. 064 (our MC) C. Mariani@XLth Rencontres de Moriond (6 th March 2005) 90%CL limit Dm 2[e. V 2] not NC 1 p 0 nm ne search 90%CL sensitivity sin 22 qme PRL 93 (2004) 051801

NEUT: K 2 K Neutrino interaction MC p p p CC quasi elastic (CCQE) n Smith and Moniz with MA=1. 1 Ge. V CC (resonance) single p(CC-1 p) n Rein and Sehgal’s with MA=1. 1 Ge. V DIS n GRV 94 + JETSET with Bodek and Yang correction. CC coherent p n Rein&Sehgal with the cross section rescale by J. Marteau NC + Nuclear Effects C. Mariani@XLth Rencontres de Moriond (6 th March 2005) s/E (10 -38 cm 2/Ge. V) Total (NC+CC) CC Total CC quasi-elastic DIS CC single p NC single p 0 En (Ge. V)

Overall normalization error on Nsk for Nov 99~ Errors (Event) Central Value 76. 05 evts KT: dominated by FV error SK: also. Stat 0. 28 0. 37% KT 3. 32 4. 37% SK 2. 28 3. 00% Flux +2. 81 -2. 59 F/N +4. 26 -5. 55 NC/CC +0. 15 -0. 23 n. QE/QE +0. 38 -0. 61 CT Total C. Mariani@XLth Rencontres de Moriond (6 th March 2005) 0. 46 0. 60% +6. 53 -7. 37 Take errors not considered in matrix 5. 34%

Null oscillation Dln. L preliminary The null oscillation probabilities are calculated based on Dln. L. K 2 K-II K 2 K-all nm disappearance 2. 72 2. 18 4. 55 En spectrum distortion 1. 63 2. 91 4. 90 Combined 4. 33 5. 19 9. 90 *: The value is changed from the previous one. Disappearance of nm and distortion of the energy spectrum as expected in neutrino oscillation. K 2 K confirmed neutrino oscillation discovered in Super-K atmospheric neutrinos. C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

The change of NSKexp in K 2 K-I (Bugs) p The detector position n 295 m 294 m -1% 294 m 295 m p MC difference between KT and SK n n KT; MA(QE)=1. 1 SK; MA(QE)=1. 0 s (NCel)KT=1. 1×s(NCel)SK Efficiency change! -1% NSKexp Change ~2% C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

CC-1 p suppression versus coherent p C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Systematic Bias without the MC correction. ND (Sci. Bar) measurement DATA; MC w/ CC-1 p suppression MC template; Default MC Oscillation Results MC w/o low q 2 correction sin 22 q=1. 00 Dm 2=2. 65 × 10 -3 e. V 2 Prob. (null oscillation)=0. 0049% Toy MC Corrected MC for low q 2 sin 22 q=1. 00 Dm 2=2. 73× 10 -3 e. V 2 Prob. (null oscillation)=0. 011% systematic bias There is a small bias in n. QE/QE and the low energy flux C. Mariani@XLth Rencontres de Moriond (6 th March 2005) n. QE/QE

Oscillation result with a default MC Without low q 2 MC correction The result w/o low q 2 MC correction gives the better (biased) measurement due to the more low energy flux and the smaller n. QE/QE. C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

K 2 K-I vs K 2 K-II p Best fit values. n sin 22 q = 1. 08, 1. 51 n Dm 2 [e. V 2] = 2. 73 10 -3, 2. 19 10 -3 p Best fit values in the physical region. n sin 22 q = 1. 00, 1. 00 n Dm 2 [e. V 2] = 2. 86 10 -3 , 2. 79 10 -3 n Dlog. L=0. 02, 0. 75 n KSK 2 K-I & K 2 K-II =77% C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Enrec for K 2 K-I and K 2 K-II K 2 K-I C. Mariani@XLth Rencontres de Moriond (6 th March 2005) K 2 K-II

K 2 K-I vs K 2 K-II C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

1 KT sys error summary and the change. p Sci. Bar sys. error p… p C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

1 KT sys. error Systematic error l Fiducial: updated l Escale : updated l FADC (scale) updated l FADC(cut position) l Background l Multi-event l Event rate(New) l Profile (New) KT origin l SK efficiency l CT norm. l Far/Near C. Mariani@XLth Rencontres de Moriond (6 th March 2005) +-4. 0% (<- 4. 0%) : Smy’s analysis +-0. 3% +-0. 8% +-1. 5% (New) : Shaomin’s analysis +-0. 5% +-0. 7% +-2. 0% +-0. 3% +-4. 9% (Prev. 4. 4%) +-3. 0% +-0. 3 % for K 2 K-II ± 0. 6% for K 2 K-I +5. 6 -7. 3%

Sci. Bar Systematic Error (2 track/1 track) l Detector oriented Ø Vertex Matching Efficiency Ø Threshold Effect (+-15%) Ø Xtalk Effect (2%/4%/6%) Ø Finding Efficiency Ø Total (Detector) l Nuclear Effect Ø Proton Re-scattering Ø Pion Absorption Ø Pion inelastic scattering Ø Total (Nuclear) +2. 9% -2. 6% +1. 7% -1. 7% +2. 3% -2. 9% +4. 1% -4. 2% l Total +5. 1% C. Mariani@XLth Rencontres de Moriond (6 th March 2005) +2. 7% +0. 7% +1. 1% +0. 9% +3. 1% -1. 0% -1. 1% -4. 3% -4. 5% -6. 2%

Sci. Bar Systematic Error (2 track QE/2 track n. QE) l Detector oriented Ø Angle resolution Ø X-talk Effect Ø Momentum scale (+-2. 7%) Ø Total (Detector) l Nuclear Effect Ø Proton Re-scattering Ø Pion Absorption Ø Pion inelastic scattering Ø Total (Nuclear Effect) l Total C. Mariani@XLth Rencontres de Moriond (6 th March 2005) +1. 0% +2. 2% -2. 9% +1. 5% -4. 3% +2. 8% -5. 2% +2. 9% -2. 8% -5. 4% +0. 3% -4. 7% +2. 9% -7. 7% +4. 0% -9. 3%

Track finding Efficiency 2 nd Track Efficiency (MC) MC true 2 nd Track (NHITX/Y≧ 3 Hit) Finding Efficiency Detected! (= 1. Could Find 2 nd Track 2. Rec. track overlap with more than 1 true Hit) 1. 0 0. 8 0. 6 0. 4 0. 2 0 Overall Eff. 59. 0% >20 Hit 85. 3% >40 Hit 91. 1% (This can be improved!) 20 40 60 80 100 120 140 (NHIT) Evaluated DATA/MC w/ Eye scan. C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Eye scan Result ● Data (Eye) □ MC (Eye) Eye scanners (M. Hasegawa , K. Hiraide Y. Takubo, S. Yamamoto) Integrated bin (>40 Hits) 1. 35 0. 93 0. 97 1. 01 1. 00 0. 96 0. 98 C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Systematic error (Finding Eff. ) Compared DATA 2 Track/1 Track (default MC) vs 2 Track/1 Track (MC* ) MC Entry (each bin MC) DATA/ MC Total <5 0 0 0 5 -9 265 1. 35 0. 54 358 143 10 -14 2257 0. 93 0. 10 2108 226 15 -19 3824 0. 97 0. 06 3719 229 20 - 24 3976 1. 01 0. 05 4034 199 25 - 29 30 - 34 3654 3027 1. 00 0. 96 0. 04 0. 03 3659 3017 146 91 35 - 39 2406 0. 98 0. 03 2364 72 40 – 8009 27418 0. 98 0. 02 (stat. err) 7849 27034 160 475 2 track/1 track : 0. 5032 (27418/54106) 0. 496 +/- 0. 013 (27034/54490) Systematic Error (Track finding Eff. ) : + 0. 9% , -4. 3% C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Same as previous one except binning size is 125/2 nsec that is a half of intervals of two bunches. C. Mariani@XLth Rencontres de Moriond (6 March 2005) th

Residual of K 2 K-SK event timing relative to neutrino beam bunches. Timing correlation is clearly seen and a sigma is C. Mariani@XLth Rencontresobtained de Moriond (6 March 2005)as about 30 nsec. th

Number of observed events (F. C. in fid. vol. ) as a function of integrated CT C. Mariani@XLth Rencontres de Moriond (6 March 2005) th

Number of observed events (F. C. in all inner volume) as a(6 function of integrated CT C. Mariani@XLth Rencontres de Moriond March 2005) th

Results (without small angle) p p 1 kt q > 20 deg. , Sci. Fi and Sci. Bar q > 10 deg. In each En bin, fitted flux is consistent each other. C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

CC 1 p suppression factor tuning p p p By using Sci. Bar 2 track-non. QE and fitted flux, I looked for the best value of CC 1 p suppression. Suppression factor q 2/A (q 2>A) Scan A value and calculate c 2 of q distribution. 2 e t a Ca c l u lc A=0. 10 +/– 0. 03 C. Mariani@XLth Rencontres de Moriond (6 th March 2005) A qm Sci. Bar 2 track non. QE CC 1 p q 2/0. 10 (Data–MC)/MC Agree quite well

Results (CC 1 p re-weighted) p p p CC 1 p re-weighting factor : q 2/0. 10 (q 2<0. 10) Flux is fixed non. QE value : 0. 979(q cut) 1. 056(this result) (+8%) C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Results (no coherent p) for comparison p Coherent p production removed. p p Flux is fixed. non. QE value: 1. 093(this results) p (CC 1 p re-weighting : 1. 056 C. Mariani@XLth Rencontres de Moriond (6 th March 2005) 3. 5% difference)

Results (no cut, no re-weighting) for comparison p p p Flux is consistent with q cut results. non. QE is significantly small, and c 2 is bad. non. QE : 0. 856, c 2 / dof = 773. 8 / 595 = 1. 30 C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Flux v. s. fitting condition p Fitted flux from q cut, CC 1 p re-weighting and no coherent are consistent each other. For comparison Official flux For comparison C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Non. QE v. s. CC 1 p re-weighting factor (Sci. Bar only fit) p CC 1 p re-weighting factor +/– 0. 03 (1 s) non. QE +/– 4% Sci. Bar Only Fit C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Likelihood for Oscillation analysis f x : Systematic error parameters Poisson prob. for FC events : # of observed events : # of expected events Period n flux K 2 K-Ia Ihorn = 200 k. A K 2 K-Ib K 2 K-II C. Mariani@XLth Rencontres de Moriond (6 th March 2005) SK parameters SK-I Ihorn = 250 k. A SK-II

Likelihood for Normalization i: energy bin j: Interaction mode Data/MC for # of events in KT # of interaction in MC SK efficiency flux n. QE/QE Far/Near C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Likelihood for Spectrum Shape flux Far/Near n. QE/QE SK SK efficiency Energy Scale Nj (Erec, Etrue): Event fraction in MC N: Normalization factor C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Likelihood for Systematic parameters neutrino flux, n. QE/QE, NC Far/Near Ratio SK efficiency Overall Normalization SK Energy Scale Systematic parameters for n flux are common for SK-Ib and SK-II # of free parameter in fit: 25 33 C. Mariani@XLth Rencontres de Moriond (6 th March 2005) 34 (fn. QE f. CC-n. QE, f. NC)

Reconstructed vertex distribution for r 2 vs Z K 2 K-1 K 2 K-2 C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Visible energy distribution for F. C. events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 22 q=1. 0, Dm 2=2. 0× 10 -3 e. V 2 (dashed histogram), and oscillated with sin 2 2 q=1. 0, Dm 2 =3. 0× 1 0 - 3 e V 2 (dotted histogram). C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Visible energy distribution for F. C. events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 22 q=1. 0, Dm 2=2. 0× 10 -3 e. V 2 (dashed histogram), and oscillated with sin 2 2 q=1. 0, Dm 2 =3. 0× 1 0 - 3 e V 2 (dotted histogram). C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Visible energy distribution for F. C. events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 22 q=1. 0, Dm 2=2. 0× 10 -3 e. V 2 (dashed histogram), and oscillated with sin 2 2 q=1. 0, Dm 2 =3. 0× 1 0 - 3 e V 2 (dotted histogram). C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Reconstructed muon momentum distribution for F. C. 1 ring mu-like events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 22 q=1. 0, Dm 2=2. 0× 10 -3 e. V 2 (dashed histogram), and oscillated with sin 22 q=1. 0, Dm 2=3. 0× 10 -3 e. V 2 C. Mariani@XLth Rencontres ( ded. Moriond o(6 March 2005) t t e d h i s t o g r a m ). th

Reconstructed muon momentum distribution for F. C. 1 ring mu-like events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 22 q=1. 0, Dm 2=2. 0× 10 -3 e. V 2 (dashed histogram), and oscillated with sin 22 q=1. 0, Dm 2=3. 0× 10 -3 e. V 2 C. Mariani@XLth Rencontres ( ded. Moriond o(6 March 2005) t t e d h i s t o g r a m ). th

Reconstructed muon momentum distribution for F. C. 1 ring mu-like events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 22 q=1. 0, Dm 2=2. 0× 10 -3 e. V 2 (dashed histogram), and oscillated with sin 22 q=1. 0, Dm 2=3. 0× 10 -3 e. V 2 C. Mariani@XLth Rencontres ( ded. Moriond o(6 March 2005) t t e d h i s t o g r a m ). th

The distribution of the reconstructed direction of muons relative to the direction from KEK to SK for F. C. 1 ring mu-like events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 2 2 q=1. 0, Dm 2 =2. 0× 1 0 - 3 e V 2 (dashed histogram), and sin 2 2 q = 1. 0 , D m 2 = 3. 0× 1 0 - 3 e V 2 ( d o t t e d h i s t o g r a m ). C. Mariani@XLthoscillated Rencontres de Moriond (6 Marchwith 2005) th

The distribution of the reconstructed direction of muons relative to the direction from KEK to SK for F. C. 1 ring mu-like events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 2 2 q=1. 0, Dm 2 =2. 0× 1 0 - 3 e V 2 (dashed histogram), and sin 2 2 q = 1. 0 , D m 2 = 3. 0× 1 0 - 3 e V 2 ( d o t t e d h i s t o g r a m ). C. Mariani@XLthoscillated Rencontres de Moriond (6 Marchwith 2005) th

The distribution of the reconstructed direction of muons relative to the direction from KEK to SK for F. C. 1 ring mu-like events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 2 2 q=1. 0, Dm 2 =2. 0× 1 0 - 3 e V 2 (dashed histogram), and sin 2 2 q = 1. 0 , D m 2 = 3. 0× 1 0 - 3 e V 2 ( d o t t e d h i s t o g r a m ). C. Mariani@XLthoscillated Rencontres de Moriond (6 Marchwith 2005) th

Reconstructed neutrino energy distribution for F. C. 1 ring mu-like events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 2 2 q=1. 0, Dm 2 =2. 0× 1 0 - 3 e V 2 (dashed histogram), and oscillated with sin 22 q=1. 0, Dm 2=3. 0× 10 -3 e. V 2 (dotted histogram). C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Reconstructed neutrino energy distribution for F. C. 1 ring mu-like events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 2 2 q=1. 0, Dm 2 =2. 0× 1 0 - 3 e V 2 (dashed histogram), and oscillated with sin 22 q=1. 0, Dm 2=3. 0× 10 -3 e. V 2 (dotted histogram) C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Reconstructed neutrino energy distribution for F. C. 1 ring mu-like events in the fiducial volume in data (closed circle), M. C. expectation with no oscillation (solid histogram), oscillated with sin 2 2 q=1. 0, Dm 2 =2. 0× 1 0 - 3 e V 2 (dashed histogram), and oscillated with sin 22 q=1. 0, Dm 2=3. 0× 10 -3 e. V 2 (dotted histogram). C. Mariani@XLth Rencontres de Moriond (6 th March 2005)

Summary of SK-2 absolute energy calibration • Data agree with MC within +/-1. 9% • Time variation : +/-0. 9% C. Mariani@XLth Rencontres de Moriond (6 th March 2005) total uncertainty : +/- 2. 1%

Ring-counting likelihood for SK-2 m-like events sub-Ge. V P<400 Me. V/c C. Mariani@XLth Rencontres de Moriond (6 th March 2005) sub-Ge. V P>400 Me. V/c multi-Ge. V

PID distributions for SK-2 C. Mariani@XLth Rencontres de Moriond (6 th March 2005) sub-Ge. V multi-Ge. V (Evis<1330 Me. V) (Evis>1330 Me. V)

Systematic error on spectrum K 2 K-1 ring counting 0. -0. 5 1. 9% 0. 5 -1. 0 2. 1% 1. -1. 5 2. 5% 1. 5 -2. 0 5. 9% 2. 0 -2. 5 5. 9% 2. 55. 9% PID 1. 1% 0. 5% 0. 7% 0. 6% 0. 7% vertex 2. 0% ring counting 0. -0. 5 2. 6% 0. 5 -1. 0 2. 2% 1. -1. 5 7. 9% 1. 5 -2. 0 7. 5% 2. 0 -2. 5 7. 1% 2. 57. 1% PID 2. 5% 0. 9% 0. 6% 0. 5% vertex 2. 0% E scale 2. 7% K 2 K-2 E scale 2. 1% C. Mariani@XLth Rencontres de Moriond (6 th March 2005)