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Neutrino Oscillation Experiment between JHF – Super-Kamiokande

Overview of JHF-SK experiment measuring neutrino oscillation parameters with various beam options. Detailed construction, operation, and physics sensitivities discussed.

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Neutrino Oscillation Experiment between JHF – Super-Kamiokande

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  1. Neutrino Oscillation Experiment betweenJHF – Super-Kamiokande Yoshihisa OBAYASHI (Kamioka Observatory, ICRR) Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  2. 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) http://neutrino.kek.jp/jhfnu Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  3. Overview of JHF – SK • nm→nx disappearance: • Precise measurement of oscillation parameters: d(Dm232)~ 2x10-4eV2, d(sin22qmx)~ 1% • nm→ne appearance: • Explore down to sin22qme ~ 5x10-3 (sin22q13 ~ 1x10-2) • Oscillation Max @ En=0.5~1.2GeV • P=sin22q・sin2(1.27Dm232L/En) • Dm232=2~5x10-3eV2, L=295km Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  4. JHF (Japan Hadrons Facility) JAERI @ Tokai-mura Construction: 2001 ~ 2006 N 50GeV PS 3GeV PS Neutrino Beam Line 600MeV Linac Front Detector(s) To Super-Kamiokande 1021p.o.t./1year(130day) Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  5. Far Detector • Super-Kamiokande @ Kamioka • Operation Start: 1996 • 295 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-m separation is performed by ring pattern likelihood Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  6. 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 Dm2 • Next 5 years: • Precise Analysis with (one of) NBB • Measurement of q23,q13 Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  7. Wide Band Beam • High Intensity • Wide sensitivity in Dm2 • Established technique • Backgrounds from HE tail • Spectra diff. btw near&far • Systematic error • Needs Heavy shielding • decay pipe must be short • ~ 4200 nm int./22.5kt/yr • (ne:0.8%) Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  8. Narrow Band Beam • Less systematic error • Less BG from HE tail • Easy to tune En • Less shielding • Low intensity • ~ 830 nm int./22.5kt/yr • (ne:0.3%@peak) Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  9. Off Axis Beam: Another option of NBB q • WBB with intentionally misaligned from detector axis En 10 20 Ep • Quasi Monochromatic Beam Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  10. Off Axis Beam • More intense than NBB • More HE tail than NBB • Hard to tune En • Needs heavy shielding • Not established technique • Beam monitor • Near/Far ratio, … • ~ 2200 nm int./22.5kt/yr • (ne:0.2%@peak) Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  11. Physics Sensitivity Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  12. nm Disappearance • Ratio after BG subtraction: • Fit with 1-sin22q・sin2(1.27Dm2L/E) Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  13. nm Disappearance • Possible systematic errors: • inelastic cross section: 20% • Spectrum @FD: 4%・E • Spectrum diff.(Near/Far): 10% • Energy measurement: 3% • d(sin22q23)~0.01 in 5 years • d(Dm223) ~ 2x10-4eV2 Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  14. nm → ne Appearance m32 Dm2atm m22 Dm2sol m12 • Three flavor oscillation framework: • Dm212 <<Dm223~Dm213≡Dm2 • Dm223= Dm2atm>10-3eV2 • Dm212= Dm2sol<10-4eV2 • Oscillation Probability P : • Present limit: sin22qme < 5x10-2 • sin22qme= sin22q13・ sin2q23 • sin22q13 <0.1(CHOOZ) • sin2q23 ~ 0.5 (Atmospheric n) • Goal: sin22qme ~ 5x10-3 Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  15. Signal & Backgrounds • Signal: ne C.C. interaction • BG 1: nm C.C. interaction • Single fuzzy ring • Cherenkov angle ~ 42deg. ne e+- shower • Sharp ring edge • Cherenkov angle < 42deg. nm m • easy to reject Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  16. Backgrounds (continued) • BG 2: N.C. p0 production n n 2 showers p0→2g • 2 fuzzy rings → hard to separate • Not reproduce En • need effort to reject Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  17. ne Selection by SK Official Cuts • S/N ~ 1/3 (@sin22qme=0.05) • Main Background come from p0 sin22qme=0.05, Dm2=3x10-3eV2 Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  18. p0 rejection • Force to find 2ndg ring • Cut with follow quantities: • Shower direction w.r.t. n (cosqne) • Energy fraction of second g R(g2)=E(g2)/(E(g1)+E(g2)) • Pattern likelihood difference • Invariant mass of 2 g Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  19. p0 cut efficiency PRELIMINARY WBB 1year NBB 1year Off Axis 1year sin22qme=0.05, Dm2=3x10-3eV2 Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  20. nm → ne Oscillation Sensitivity • sin22qme~5(3)x10-3@90%CL by 5year run of NBB(off axis beam) PRELIMINARY 10% systematic in BG rate is considered Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  21. nm → ne Oscillation Sensitivity 10% systematic in BG rate is considered PRELIMINARY Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  22. Comparison to MINOS • JHF neutrino is more sensitive especially in Atmospheric Dm2 region MINOS Ph2he,me,le 2yr exposure (hep-ph0005012) Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  23. nm→ nt? nsterile? • NC p0 production: • n + N → n + N + p0 • In the case of nm→ nsterile oscillation, • Number of p0 also decrease • nt ⇔ nsterile discrimination Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  24. Summary • JHF neutrino experiment • Expected to start in 2006 • Far Detector: Super-K • By 5 years of run: • nm disappearance search • d(Dm223) ~ 2x10-4eV2 • d(sin22q23) ~ 1% • ne appearance search • sin22q13 ~ 10-2 @90%CL • nm⇔nt or nm⇔nsterile • Can be tested Yoshihisa OBAYASHI, Oct. 2000 @Seoul

  25. Test of CP Violation • If sin22q13 ~ 0.01, sin22q12,Dm212~LMA • 1MW(2deg. off axis) → SK : • 2 nm → ne / year • Too few to see CP • 4MW → Mton : • 300 nm → ne / year • 100 nm → ne / year • 1year n + 3year n • 600 total events with asym: 150xsind • d=30deg.(3s), 12deg.(90% CL) Yoshihisa OBAYASHI, Oct. 2000 @Seoul

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