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The JHF-Kamioka Neutrino experiment

Jan 16, 2002 @IIAS. The JHF-Kamioka Neutrino experiment. Tsuyoshi NAKAYA (Kyoto U.) for JHF-SK working group. Introduction Overview of the experiment Physics sensitivity in Phase-I Physics sensitivity in Phase-II Summary and Conclusion.

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The JHF-Kamioka Neutrino experiment

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  1. Jan 16, 2002 @IIAS The JHF-Kamioka Neutrino experiment Tsuyoshi NAKAYA (Kyoto U.) for JHF-SK working group • Introduction • Overview of the experiment • Physics sensitivity in Phase-I • Physics sensitivity in Phase-II • Summary and Conclusion JHF is an tentative name, and will be renamed soon.

  2. JHF-SK Neutrino Working Group ICRR/Tokyo-KEK-Kobe-Kyoto-Tohoku-TRIUMF Y. Itow, T. Kajita, K. Kaneyuki, M. Shiozawa, Y. Totsuka (ICRR/Tokyo) Y. Hayato, T. Ishida, T. Ishii, T. Kobayashi, T. Maruyama, K. Nakamura, Y. Obayashi, M. Sakuda (KEK) S. Aoki, T.Hara, A. Suzuki (Kobe) A. Ichikawa, T. Nakaya, K. Nishikawa (Kyoto) T. Hasegawa, K. Ishihara, A. Suzuki (Tohoku) A.Konaka (TRIUMF, CANADA) In addition to the above user group, the neutrino facility construction group is OFFICIALLY formed at KEK. 15,5

  3. 1.Introduction The experiment will start in 2007. Kamioka ~1GeV n beam JAERI (Tokaimura) Super-K: 22.5 kt Hyper-K: 1000 kt 0.77MW 50 GeV PS 4MW 50 GeV PS ( conventional n beam) Phase-I (0.77MW + Super-K) Phase-II (4MW+Hyper-K) ~ Phase-I  200

  4. Lepton Sector Mixing q12, q23, q13 + d Dm212, Dm223 MNS (Maki-Nakagawa-Sakata) matrix

  5. n oscillation at q23~p/4 and q13~0

  6. Targets of JHF-SK experiment • Confirmation of nmnt • Discovery of nmneat Dm2atm. • Precise measurement of neutrino oscillation. (observation of oscillation peak) • CP violation in neutrino oscillation. • Confirm or Reject LSND anomaly.

  7. 2. Overview of the experiment Super Conducting magnet for n beam line JAERI@Tokai-mura (60km N.E. of KEK) Construction 2001～2006 (approved) Near n detectors @280m and @~2km 1021POT(130day)≡ “1 year”

  8. m nm + n → m + p (Em, pm) n p n beam at JHF • Principle • Intense Narrow Band Beam • Beam energy is tuned to be at the oscillation maximum. • High sensitivity • Less background • ~1 GeV beam energy for Quasi-elastic interaction. Dm2=1.6~4x10-3eV2 En=0.4~1.0GeV s=80MeV En(reconstruct) – En (True) (MeV)

  9. Far Det. q Decay Pipe Horns Target En Off Axis Beam (ref.: BNL-E889 Proposal) WBB w/ intentionally misaligned beam line from det. axis Decay Kinematics ~2° ～3100 int./22.5kt/yr w/ 80m long decay volume ne: 1.0% (0.2% @ peak) (Present design; 130m  40% more n )

  10. Phase-I: Suker-K 22.5kt (50kt) n detectors at JHF Phase-II: Hyper-K 1Mton (fiducial) volume: Super-K 70m 40m Total Length 400m (8 Compartments) 1 Mton (fiducial) volume: Total Length 400m (8 Compartments) We are investigating the possible site at Kamioka.

  11. Near Detectors(Detectors at two locations are essential.) @280m (1~10 events/spill/100ton) Fine Grained w/ magnet. • Measure n direction and spectrum. • Measure wrong sign component (see CP section). • Will be used for n interaction study with NBB. • Non-oscillation n physics. @~2km (0.1 events/spill/100ton) Water Cherenkov + Fine Grained • Measure n spectrum and ne background since they are same as those at Kamioka. • Test LSND anomaly if Mini-Boone failed to test it or discovered the new physics.

  12. spectrum 1.5km At >1.5km, the n source is treated as a point source 295km 0.28km Far/Near Spectrum Ratio n p Low Ep High Ep

  13. 3. Physics sensitivity in Phase-I (w/ Super-K) 5years (51021POT) running  precise measurement of Dm232 , q23 and q13 • nmnm (Dm232 , q23 ) • nmne (q13 , open window for CP study) • nmnt w/ NC interactions. (confirmation) • stringent limit on the non-oscillation scenario and the existence of ns. Sensitivity (goal): dsin22q23 < 0.01 sin22q13 < 0.006 (90% CL) dDm232< 1×10-4eV2 at (sin22q=1.0, Dm2=3.2×10-3eV2)

  14. nm →nt confirmation w/ NC interaction • NC p0 interaction (n + N →n + N + p0) • nmne CC + NC(~0.5CC) ~0 (sin22qme~0) nm CC + NC(~0.5CC) ~0 (maximum oscillation)nt NC #p0 is sensitive to nt flux. Limit on ns (df(ns)~0.1) nmnt OAB CC nt t #p0 + #e-like D=390±44 nt NC nt nmns p0 Dm232 3.510-3

  15. m e p0 ne appearance

  16. 3 ×10-3 ne appearance Background rejection against NC p0 is improved. sin22qme=0.05 (sin22qme 0.5sin22q13) Dm2 CHOOZ ×20 improvement sin22qme

  17. Ratio after BG subtraction nm disappearance Fit with 1-sin22q・sin2(1.27Dm2L/E) 1ring FC m-like (linear) Dm2=3×10-3 sin22q=1.0 Oscillation with Dm2=3×10-3 sin22q=1.0 Non-QE (log) No oscillation sin22q ~3% Dm2 Reconstructed En (MeV) dsin22q23 ~ 0.01 dDm232< 1×10-4eV2

  18. 4. Physics sensitivity in Phase-II (w/ Hyper-K) 2 years (101021POT) for nm and 6 years (301021POT) for nm running  Search for CP violation in n oscillation. • standard: nmne vsnmne • non-standard: nmntvsnmntw/ NC  Search for nmne  Search for proton decays. Sensitivity (goal): sin22q13 < 1×10-3 (90% CL) |d| >20 (3s discovery) at (Dm122=5×10-5eV2 , Dm232=3×10-3eV2) tproton•B(pep0, nK) > 1035 years

  19. CP violation in n oscillation Acp L=295km : small matter effect En~1 GeV : large CP asymmetry

  20. nm -15%@peak nm 1021POT/yr (1st phase) nm/nm flux for CP violation search. CC interaction Flux nm cross section difference Sign flip by change of horn plarity nm Wrong sign BG

  21. CP Violation Study NO CP violation w/o matter effect. • Compare nmne withnmne N(e+) Dm122=5×10-5eV2 , Dm232=3×10-3eV2 sin22q13 = 0.01 q23 = p/4, q12 = p/8 |d|>20(3s discovery) N(e-)

  22. 5. Summary and Conclusion • The experiment is expected to start in 2007 at the same time of the completion of JHF 50 GeV PS. • The experiment is not approved yet, and we need your STRONG support to put the experiment on track. • The features of the experiment are: • MW class 50 GeV proton accelerator (0.77MW  4MW) • ~1GeV Narrow band neutrino beam at the oscillation maximum (L=295km). • Gigantic Water Cherenkov detectors with/ neutrino energy reconstruction by quasi-elastic interaction. (22.5kton  1000kton)

  23. Physics Reach (see hep-ex/0106019) • Phase-I (0.77MW + 22.5kt): NC interaction:Establish nmnt and limit on nmns nmnm :dsin22q23 < 0.01 nmne :sin22q13 < 0.006 (90% CL) nmnm :dDm232< 1×10-4eV2 at (sin22q=1.0, Dm2=3.2×10-3eV2) • Phase-II (4MW + 1000kt): nmne :sin22q13 < 1×10-3 (90% CL) nmne vs nmne : |d|>20 (3s discovery) at (Dm122=5×10-5eV2 , Dm232=3×10-3eV2) tproton•B(pep0, nK) > 1035 years

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