Yoshihisa OBAYASHI, Oct. Neutrino Oscillation Experiment between JHF – Super-Kamiokande Yoshihisa OBAYASHI (Kamioka Observatory, ICRR)

Yoshihisa OBAYASHI, Oct. JHF Neutrino Working Group Y. Itow, Y. Obayashi, Y. Totsuka (ICRR) Y. Hayato, H. Ishino, T. Kobayashi, K. Nakamura, M. Sakuda (KEK) T. Hara (Kobe) T. Nakaya, K. Nishikawa (Kyoto) T. Hasegawa, K. Ishihara, A. Suzuki (Tohoku) A. Konaka (TRIUMF)

Yoshihisa OBAYASHI, Oct. Overview of JHF – SK  → x disappearance: Precise measurement of oscillation parameters:  (  m 23 2 )~ 2x10 -4 eV 2,  (sin 2 2   x )~ 1%  → e appearance: Explore down to sin 2 2   e ~ 5x10 -3 (sin 2 2  13 ~ 1x10 -2 ) Oscillation E =0.5~1.2GeV P=sin 2 2  ・ sin 2 (1.27  m 23 2 L/E )  m 23 2 =2~5x10 -3 eV 2, L=295km

Yoshihisa OBAYASHI, Oct. JHF (Japan Hadrons Facility) Tokai-mura 600MeV Linac 3GeV PS 50GeV PS N Front Detector(s) Neutrino Beam Line To Super-Kamiokande Construction: 2001 ~ 2006 J H FMINOSK 2 K E(GeV) Int.(10 12 ppp) Rate(Hz) Power(MW) p.o.t./1year(130day)

Yoshihisa OBAYASHI, Oct. Far Detector Kamioka Operation Start: km from JAERI 50.0kt Pure Water in the tank 22.5kt Fiducial Volume as a neutrino target Energy measurement by total amount of Cherenkov light e-  separation is performed by ring pattern likelihood

Yoshihisa OBAYASHI, Oct. Neutrino Beam at JHF Three Possible options: Wide Band Beam (WBB) 2 horns, almost same as K2K Narrow Band Beam (NBB) Horn(s) + Bending Off Axis Beam Another option of NBB Present Strategy: First 1(~2) year: High Statistics Run with WBB Pin down  m 2 Next 5 years: Precise Analysis with (one of) NBB Measurement of  23,  13

Yoshihisa OBAYASHI, Oct. Wide Band Beam High Intensity Wide sensitivity in  m 2 Established technique  Backgrounds from HE tail  Spectra diff. btw near&far Systematic error  Needs Heavy shielding decay pipe must be short ~ 4200  int./22.5kt/yr ( e:0.8%)

Yoshihisa OBAYASHI, Oct. Narrow Band Beam Less systematic error Less BG from HE tail Easy to tune E Less shielding  Low intensity ~ 830  int./22.5kt/yr (

Yoshihisa OBAYASHI, Oct. Off Axis Beam: Another option of NBB WBB with intentionally misaligned from detector axis   Quasi Monochromatic Beam EE E

Yoshihisa OBAYASHI, Oct. Off Axis Beam More intense than NBB  More HE tail than NBB  Hard to tune E  Needs heavy shielding  Not established technique Beam monitor Near/Far ratio, … ~ 2200  int./22.5kt/yr (

Yoshihisa OBAYASHI, Oct. Physics Sensitivity

Yoshihisa OBAYASHI, Oct.  Disappearance Ratio after BG subtraction: Fit with 1-sin 2 2  ・ sin 2 (1.27  m 2 L/E)

Yoshihisa OBAYASHI, Oct.  Disappearance Possible systematic errors: inelastic cross section:20% 4% ・ E Spectrum diff.(Near/Far):10% Energy measurement: 3%  (sin 2 2  23 )~0.01 in 5 years  (  m  23 ) ~ 2x10 -4 eV 2

Yoshihisa OBAYASHI, Oct.  → e Appearance Three flavor oscillation framework:  m 2 12 <<  m 2 23 ~  m 2 13 ≡  m 2  m 2 23 =  m 2 atm >10 -3 eV 2  m 2 12 =  m 2 sol <10 -4 eV 2 Oscillation Probability P : Present limit: sin 2 2   e < 5x10 -2 sin 2 2   e = sin 2 2   ・  sin 2   sin 2 2   <0.1(CHOOZ) sin 2   ~ 0.5 (Atmospheric ) Goal: sin 2 2   e ~ 5x10 -3 m22m22 m12m12 m32m32  m 2 atm  m 2 sol

Yoshihisa OBAYASHI, Oct. Signal & Backgrounds Signal: e C.C. interaction BG 1:  C.C. interaction Single fuzzy ring Cherenkov angle ~ 42deg. e e +- shower Sharp ring edge Cherenkov angle < 42deg.    easy to reject

Yoshihisa OBAYASHI, Oct. Backgrounds (continued) BG 2: N.C.  0 production   →  2 showers → 2 fuzzy rings → hard to separate Not reproduce E  need effort to reject

Yoshihisa OBAYASHI, Oct. e Selection by SK Official Cuts S/N ~ 1/3 2 2  e =0.05 ) Main Background come from  0  (w/  0 ) e Fid. Vol R e-like reduct.rate2.5%8.6%55.3% sin 2 2e=0.05, m 2 =3x10 -3 eV 2

Yoshihisa OBAYASHI, Oct.  0 rejection Force to find 2 nd  ring Cut with follow quantities: Shower direction w.r.t. (cos  e ) Energy fraction of second  R(  2 )=E(  2 )/(E(  1 )+E(  2 )) Pattern likelihood difference Invariant mass of 2 

Yoshihisa OBAYASHI, Oct. PRELIMINARY  0 cut efficiency WIDE  e Fid. Vol R e-like 92(2.5%)29.5(55.3%)  0 cut 4.0( 0.1% )9.8( 18.4% ) 2deg.  e Fid. Vol R e-like 37.4(2.1%)32.1(70.5%)  0 cut 3.8( 0.2% ) 24.3(53.4%) LE2  e Fid. Vol R e-like 13.2(1.8%)16.2(70.4%)  0 cut 1.8( 0.2% ) 11.6(50.4%) WBB 1year NBB 1year Off Axis 1year sin 2 2e=0.05, m 2 =3x10 -3 eV 2

Yoshihisa OBAYASHI, Oct.  → e Oscillation Sensitivity sin 2 2   e ~5(3)x10 by 5year run of NBB (off axis beam) PRELIMINARY 10% systematic in BG rate is considered

Yoshihisa OBAYASHI, Oct.  → e Oscillation Sensitivity PRELIMINARY 10% systematic in BG rate is considered

Yoshihisa OBAYASHI, Oct. Comparison to MINOS  JHF neutrino is more sensitive especially in Atmospheric  m 2 region MINOS Ph2he,me,le 2yr exposure (hep-ph )

Yoshihisa OBAYASHI, Oct.  →  ? sterile ? NC  0 production:  + N →  + N +  0 In the case of  → sterile oscillation, Number of  0 also decrease   ⇔ sterile discrimination CCNC  Yes  FewYes sterile No

Yoshihisa OBAYASHI, Oct. Summary JHF neutrino experiment Expected to start in 2006 Far Detector: Super-K By 5 years of run:  disappearance search  (  m 2 23 ) ~ 2x10 -4 eV 2  (sin 2 2  23 ) ~ 1% e appearance search sin 2 2  13 ~ 10  ⇔  or  ⇔ sterile Can be tested

Yoshihisa OBAYASHI, Oct. Test of CP Violation If sin 2 2  13 ~ 0.01, sin 2 2  12,  m 2 12 ~LMA 1MW(2deg. off axis) → SK : 2  → e / year  Too few to see CP 4MW → Mton : 300  → e / year 100  → e / year 1year + 3year 600 total events with asym: 150xsin    =30deg.(3  ), 12deg.(90% CL)