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n e appearance search

n e appearance search. Yoshihisa OBAYASHI (KEK - IPNS). n m to n e oscillation search. Three Active Neutrino & Mass Degeneration Scenario : D m 2 12 << D m 2 13 ~ D m 2 23 Present Limit: sin 2 2 q 13 <10 -1 @ D m 2 ~3x10 -3 eV 2 Obtained by CHOOZ (PALO VERDE) experiment

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n e appearance search

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  1. JHF-SK neutrino workshop ne appearance search Yoshihisa OBAYASHI (KEK - IPNS)

  2. nm to ne oscillation search • Three Active Neutrino & Mass Degeneration Scenario : Dm212<<Dm213~Dm223 • Present Limit: sin22q13<10-1@Dm2~3x10-3eV2 • Obtained by CHOOZ (PALO VERDE) experiment • Neutrino Beam is Essentially Pure nm • (nm : ne~100:0.2@peak) • ne appearance search = small q13 search ~0.5 from SK Atm. n JHF-SK neutrino workshop @ KEK

  3. Appearance Signal • ne C.C. interaction • Single Fussy Ring • Cherenkov Angle ~ 42o ne e+- shower JHF-SK neutrino workshop @ KEK

  4. BG(1): nm C.C. interaction • Sharp Ring Edge • Cherenkov Angle < 42o • easy to reject nm m JHF-SK neutrino workshop @ KEK

  5. BG(2): N.C. p0 production • p0→2g : 2 Shower Rings • 2 rings overlap • A ring is too weak • Not Reproduce En Single Ring n n p0→2g 2 showers JHF-SK neutrino workshop @ KEK

  6. p0 production • Sudden raise from En~500MeV s(w/p0)/s(total) En(GeV) JHF-SK neutrino workshop @ KEK

  7. ne selection • SK Atmn official selection (single-ring e-like): • Fully Contained (No Anti-counter Activity) • Only one ring is reconstructed • PID likelihood is e-like (Showering) • No Muon Decay Electron • Evis > 100MeV Dm2=3x10-3eV2, sin22qme=0.05 Too Much! JHF-SK neutrino workshop @ KEK

  8. Tight e/p0 separation • p0 BG tend to have a forward peak • cosqne: Large for BG • 2nd ring for the signal is fake • E(g2)/E(g1+g2): Large for BG • Likelihood diff. between 1-ring and 2-rings • Invariant mass JHF-SK neutrino workshop @ KEK

  9. e/p0 separation efficiency Dm2=3x10-3eV2, sin22qme=0.05 JHF-SK neutrino workshop @ KEK

  10. p0 contamination • Black: Single-ring e-like ~2% • Green: Standard p0 rejection ~0.2% • Red: More tight p0 rejection ~0.1% Eff. Identified as ne En(GeV) JHF-SK neutrino workshop @ KEK

  11. BG(3): nt C.C. • nmnt+N t e could be a source of BG • Energy threshold > 3 GeV • Negligibly small JHF-SK neutrino workshop @ KEK

  12. Expected Signal & BG distribution • Reconstruct En as Quasi-Elastic interaction • Apply Energy Cut • 0.4GeV< E <1.2GeV (OAB2o) OAB2o 5year JHF-SK neutrino workshop @ KEK

  13. Sensitivity for Mixing Angle sin22qme sensitivity JHF-SK neutrino workshop @ KEK

  14. Sensitivities • Sensitive down to sin22qme>3x10-3@Dm2=3x10-3eV2 • By tuning En, sensitive down to sin22qme>5x10-3 in all allowed Dm2atm • sin22q13>1x10-2 JHF-SK neutrino workshop @ KEK

  15. Sensitivities (2) JHF-SK neutrino workshop @ KEK

  16. Comparison to Other Projects • MINOS: • Too high En • ntCC→t→e may be a serious BG • OPERA(,ICARUS) • Target physics is different (nt app.) • Much more high En • Small Far Detector JHF-SK neutrino workshop @ KEK

  17. Summary • ~1 GeV neutrino beam + SK(Water Cherenkov) seems to be a best solution to search: 0.01 < sin22q13 < 0.1 @ Dm2atm. • Expected sensitivity: sin22q13~ 0.01 @ 90%C.L. • JHFnu-SK has much higher sensitivity for ne appearancesearch than MINOS and OPERA. JHF-SK neutrino workshop @ KEK

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