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J-PARC Neutrino Experiment ( T2K )

ICEPP Sympo. @ Hakuba Feb 15-18, 2004. J-PARC Neutrino Experiment ( T2K ). T.Nakaya Kyoto University. January 2004. LOI to the J-PARC office (Jan, 2003) Japan: 45, US:38, Canada: 19, Europe: 31, other Asia: 14. 1. Introduction.

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J-PARC Neutrino Experiment ( T2K )

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  1. ICEPP Sympo. @ Hakuba Feb 15-18, 2004 J-PARCNeutrino Experiment (T2K) T.Nakaya Kyoto University

  2. January 2004 LOI to the J-PARC office (Jan, 2003) Japan: 45, US:38, Canada: 19, Europe: 31, other Asia: 14

  3. 1. Introduction • A next goal of neutrino experiments is to explore the neutrino oscillation phenomena beyond the discovery phase. • Three generation Matrix (NMS matrix) • CP Violation,matter effect, the sign of Dm232 • Unexpected physics behind the oscillation phenomena. • More complete studies with high statistics by J-PACR neutrino experiment: • more precision • q23, Dm223, oscillation curve, non-oscillation scenario • more sensitivity to a rare process • q13 (nmne), CP Violation, unexpected phenomena.

  4. J-PARC Neutrino Experiment (hep-ex/0106019) Start at the beginning of 2009 Kamioka ~1GeV n beam JAERI (Tokai) Super-K: 22.5 kt 0.75MW 50 GeV PS ( conventional n beam) J-PARC 0.75MW + Super-Kamiokande ( Future: Super-JPARC 4MW + Hyper-K ~ J-PARC+SK 200 )

  5. Strategy • High statistics by a high intense n beam • Tune En at the oscillation maximum • Narrow band beam to reduce BG • Sub-GeV n beam for Water Cherenkov 0.75MW JHF 50GeV-PS (4MW Super JHF) Super-Kamiokande (Hyper-Kamiokande) Off-Axis n beam

  6. News • Dec.20,2003 • Neutrino project on the draft budget from MOF • 5 years project from JFY2004 ~ JFY2008 • Start the experiment at the end of JFY2008. J-PARC neutrino facility approved!

  7. J-PARC(Japan Proton Accelerator Research Complex) Construction started in 2001 Nuclear and Particle Experimental Facility Materials and Life Science Experimental Facility Nuclear Transmutation Neutrino experimental hall 3 GeV Synchrotron (25 Hz, 1MW) 50 GeV Synchrotron (0.75 MW) Linac (350m) J-PARC = Japan Proton Accelerator Research Complex

  8. December, 2003 n to Kamioka December, 2003

  9. World’s Proton Accelerators

  10. J-PARC Neutrino Facility J-PARC Construction 2001～2007 Transport line (Super-cond. Mag.) (0.77MW) Target station Decay volume • 8 bunches/~5ms • 3.3x1014proton/pulse • 3.94 (3.64) sec cycle • 1ｙｒ≡1021POT (130 days) Near detectors (280m,2km)

  11. Special Features Superconducting magnets Off-axis beam Components Primary proton beam line Normal conducting magnets Superconducting arc Proton beam monitors Target/Horn system Decay pipe (130m) cross w/ 3NBT Cover Off-Axis angle 2~3 deg. Beam dump muon monitors Near neutrino detectors Proton beam transport Target Station 3NBT 130m decay pipe 280m m-pit Near detector

  12. Development of Superconducting magnets • Arc Section(R=105m) • Superconductingcombined functionmagnets • First application in the world • Reduce cost (4028mags). • Larger acceptance Cryo.Sci.C. KEK Test winding of a coil

  13. Off Axis Beam (2 - 3 ) Far Det. (ref.: BNL-E889 proposal: http://minos.phy.bnl.gov/nwg/papers/E889) Decay Pipe q Horns Osc. Prob.=sin2(1.27Dm2L/En) Target WBB w/ intentionally misaligned beam line from det. axis Dm2=3x10-3eV2 L=295km Decay Kinematics osc.max. nm q=0 En OA1° q=1.0 OA2° OA3° 1 q=2.0 q=3.0 0 5 Ep ～3000 CC int./22.5kt/yr ne: 1.0% (0.2% @ peak); En

  14. nm nm/nm flux for CP violation search (2nd phase?) CC interaction Flux nm cross section difference nm -15%@peak Sign flip by change of horn polarity nm Wrong sign BG 1021POT/yr (1st phase)

  15. Detectors p p n • Muon monitors @ ~140m • Fast (spill-by-spill) monitoring of beam direction/intensity • First Front detector@280m • Neutrino Fluxdirection • Study neutrino interactions. • Second Front Detector @ ~2km • Almost same En spectrum as for SK • Water Cherenkov can work • Far detector @ 295km • Super-Kamiokande (50kt) 0m 140m 280m 2 km 295 km Neutrino spectra at diff. dist 1.5km 295km 0.28km dominant syst. in K2K

  16. Far detectorSuper-Kamiokande ４１．４ｍ ４０ｍ （since Apr 1９９６） 50,000 tonwater Cherenkov detector (22.5 kton fiducial volume)

  17. Far detector SK is back ! Full water 10-Dec.-2002 w/ half coverage (20%) Jan.-2003, fully contained event Back to full coverage (40%) Scheduled in winter of 2005 Acrylic + FRP vessel Sep.-2002, before water filling

  18. nm + n → m + p (Em, pm) n s=80MeV En(reconstruct) – En (True) (MeV) En reconstruction in Water Cherenkov Assume CC Quasi Elastic (QE) reaction m p 1R-FCm cc-inelastic ccQE beam energy

  19. Physics Goal at the 1st phase ★Precise measurement of neutrino mixing matrix Accuracy: sin22θ23・・・・・・1% Δm223・・・・・・・・・・a few % (< 1×10-4 eV2) ★Discovery and measurement of non-zero θ13 sin22θ13・・・・・・> 0.006 1st Evidence of 3-flavor mixing ! 1st step to a CP measurement

  20. ne n3 nt nm Dm2atm n2 n1 Dm2sun Oscillation Probabilities when • q23: nm disappearance • q13: ne appearance common 3-flavor Oscillation ~1 ~0.5

  21. m e p0 ne appearance in T2K (phase 1) 1RFC w/ p0 cut 22.5kt FV • Back ground for ne appearance search • Intrinsic ne component in initial beam • Merged p0 ring from nm Requirement 10% uncertainty for BG estimation

  22. Tight e/p0 separation • Shower direction from the beam axis • cosqne: g from coherent p0 tends to have a forward peak • Force to find 2nd ring and… • E(g2)/E(g1+g2): The second ring energy is larger for BG • Likelihood diff. between 1-ring and 2-rings • Invariant mass: Small for ne nmBG  cosqne E(g2)/E(g1+g2) Likelihood Mgg ne cosqne E(g2)/E(g1+g2) Likelihood Mgg

  23. sin22q13 from ne appearance (5 years running) at Off axis 2 deg, 5 years CHOOZ excluded Dm2 Off axis 2 deg, 5 years eff. =42% (66% for QE) Sin22q13>0.006 0.5 sin22q13 (*) will be improved

  24. (log) Dm2=3×10-3 sin22q=1.0 sin22q ~3% Dm2 nm disappearance 1ring FC m-like dsin22q Oscillation with Dm2=3×10-3 sin22q=1.0 d(sin22q) OAB-2degree Non-QE 0.01 310-3 True Dm2 Reconstructed En (MeV) dsin22q23 ~ 0.01 dDm232< 1×10-4eV2

  25. nm →nt confirmation w/ NC interaction • NC p0 interaction(n + N →n + N + p0) • nmne CC + NC(~0.5CC) ~0 (sin22q13~0) 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 CC nt t #p0 + #e-like D=390±44 nt NC nt nmns p0 3.510-3 Dm232

  26. CP d -d, a -a fornmne T2K n oscillation probability(Consider the difference from a reactor measurement) q13 CP conserving solar n matter effect Sij=sinqij, Cij=cosqij [eV2]

  27. sin22q13=0.01 total q13 CP CP solar nmne oscillation probability in T2K matter

  28. Summary • Precision study of neutrino oscillation • Next step after the discovery • We may find a hint for next break-through. • J-PARC neutrino experiment (2008~) • J-PARC 50GeV-PS+Off Axis beam+Super-K • Narrow band beam at the oscillation maximum (~ 1GeV) • ne appearance, discovery of q13 (sin q13>0.006,90%CL)

  29. Supplement

  30. ne contamination in the beam Off-Axis Beam ~1/500 ne from m + K from K Intrinsic background: ne /nm (peak)~ 0.002

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