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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. ne appearance search Yoshihisa OBAYASHI (KEK - IPNS) Yoshihisa OBAYASHI

  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) • Optimum neutrino energy: below 1GeV Yoshihisa OBAYASHI

  3. Appearance Signal • Q.E.ne C.C. interaction • No hadron • No recoiled proton ring • Single electron shower • Single Fussy Ring • Cherenkov Angle ~ 42o • En can be reconstructed e+- shower ne Yoshihisa OBAYASHI

  4. BG(1): nm C.C. interaction • Sharp Ring Edge • Cherenkov Angle < 42o • Good PID (atm. n study) • Easy to reject nm m Yoshihisa OBAYASHI

  5. BG(2): N.C. p0 production • p0→2g • If 2 rings overlap or A ring is too weak • single ring like • Not Reproduce En n n p0→2g 2 showers Yoshihisa OBAYASHI

  6. 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) • Evis > 100MeV • No Muon Decay Electron Dm2=3x10-3eV2, sin22qme=0.05 Number of events for JHF(0.77MW) 5yr exposure to Super-Kamiokande(22.5kt) • We need to reject more! Yoshihisa OBAYASHI

  7. Tight e/p0 separation • Shower direction w.r.t. beam • cosqne: g from p0 tend to have a forward peak • Force to find 2nd ring and… • E(g2)/E(g1+g2): Large for BG • Likelihood diff. between 1-ring and 2-rings • Invariant mass: Small for ne Yoshihisa OBAYASHI

  8. Expected Backgrounds & Signal Dm2=3x10-3eV2, sin22qme=0.05 Number of events for JHF(0.77MW) 5yr exposure to Super-Kamiokande(22.5kt) Yoshihisa OBAYASHI

  9. Expected Signal & BG distribution • Reconstruct En as Quasi-Elastic interaction • Apply Energy Cut • 0.4GeV< E <1.2GeV (OAB2o) OAB2o 5year Yoshihisa OBAYASHI

  10. Sensitivity for Mixing Angle sin22qme sensitivity Yoshihisa OBAYASHI

  11. 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 @90% C.L. Yoshihisa OBAYASHI

  12. Comparison to Other Projects • MINOS: • High En • ntCC→t→e may be a serious BG • OPERA(,ICARUS) • Tuned to find nt appearance • More high En • Small Far Detector • JHF neutrino has highest sensitivity in ne appearance search Yoshihisa OBAYASHI

  13. Summary • ~1 GeV neutrino beam + SK(Water Cherenkov) is a good solution to search: 0.01 < sin22q13 < 0.1 @ Dm2atm. • Expected sensitivity: sin22q13~ 0.01 @ 90%C.L. • ne appearance sensitivity of JHFnu+SK is higher than MINOS, OPERA. Yoshihisa OBAYASHI

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