T2K experiment at J-PARC

1. T2K experiment at J-PARC • Neutrino oscillations • what remains to be measured • experimental approach • T2K goals, design • & construction • Current status For T2K Collaboration Danuta Kiełczewska Warsaw University & Sołtan Institute for Nuclear Studies D. Kiełczewska Epiphany 2010, Kraków

2. νμ νe ντ What we know and don’t know about neutrino masses 1 eV log m log m2 Δm212 = 7.6 x 10-5 eV2 10-1 eV |Δm223|=2.4 x 10-3 eV2 Δm223 >0 Δm223 <0 10-2 eV What is the hierarchy? D. Kiełczewska

3. What do we know about mixing? solar atmospheric 0νββ - is it maximal? which octant? <- more precisely We need to measure: D. Kiełczewska

4. Global analysis on the basis of the data at Nu2008 T. Schwetz et al. arXiv:0808.2016 SNO: arXiv:0910.2984 What is expected ? 0.04 <0.15 D. Kiełczewska

5. 63 models, arXiv:hep-ph/0608137 We would better measure it! D. Kiełczewska

6. Δm2atm Δm2solar νμ νe ντ How to measure • We need: • an experiment with L/E • corresponding to • transition to/from • good precision (a few %) • Reactor disappearance • Accelerator appearance mass hierarchy CP violation D. Kiełczewska

7. D. Kiełczewska

8. Accelerator experiments of second generation • Powerful neutrino sources • „off axis” beams T2K Nova site Japan USA beamsince 1/04/2009 NuMi (upgraded) Eν(peak) 0.76 GeV 2.22 GeV distance 295 km 812 km Far detector Super-Kamiokande to be built of mass (FV) 22.5 ktons 14 ktons Status Starts taking data Excavations started Owing to higher energy and larger distance, NOvA will be more sensitive to matter effects (mass hierarchy). Combining the NOvA and T2K results willfacilitate theseparation of CP from matter effects. D. Kiełczewska

9. T2K experiment(Tokai to Kamioka) D. Kiełczewska

10. T2K Collaboration SINS Warsaw NINP Krakow Warsaw Technical U 508 D. Kiełczewska

11. T2K Off Axis Beam Quasi monochromatic beam Kinematics of π decay 295 km • Tunable neutrino energy to oscillataion maximum • Reduced tail at high ν energies helps to reduce • backgrounddue to production Neutrino energy D. Kiełczewska

12. J-PARC accelerator laboratory in Tokai D. Kiełczewska

13. From Linac to 3 GeV From 3 GeV to Materials and Life 3 GeV Extraction Point Middle of Linac Tunnel Neutrino Tunnel 50 GeV Tunnel Upstream of Linac Tunnel JPARC Tunnel Tour D. Kiełczewska

14. (including all 3 horns) Near detector ND280 D. Kiełczewska

15. Beam commissioning (Apr- May 2009) Protons extracted from MR with superconducting magnets. Proton beam tuned within 3mm to the designed orbit D. Kiełczewska

16. Muon monitor Array of Si photodiodes and ionization chambers Focusing effect of a horn with 273 kA D. Kiełczewska

17. For precision measurements • We need: • precise beam determination in particular we need to know • Far/Near ratio with an accuracy of 2-3% NA61 /SHINE experiment talk by Magda Posiadała • cross –section measurements • νe component in the νμ beam near detectors D. Kiełczewska

18. Near Detector ND280 D. Kiełczewska

19. ND280 off-axis detector • UA1 magnet 0.2 T • inner volume 3.5x3.6x7 m3 • P0D – optimized for NC π0 production scintil. bars covered with lead & water layers SMRD counters in magnet slits • Tracker - optimized for neutrino • spectrum determination • FGD (to select CCQE events) • (scintil bars and water layers • TPC (e/μ sepeartion and • momentum measurement) • ECAL– elmgt calorimet. • SMRD – muon ranger SMRD talk by M. Ziembicki D. Kiełczewska

20. Installation of magnet and SMRD(2008-2009) D. Kiełczewska

21. ND280 components (now installed) TPC FGD To test the performance of the TPC, electrons, pions, muons, and protons were used in TRIUMF (momenta up to 400 MeV/c). INGRID D. Kiełczewska

22. First neutrino event in ND280 INGRID – on axis detector to determine beam’s direction and profile Consists of 14 modules (16 planned) Every module (1x1x1 m3) composed of 11 alternating planes of plastic scintillators (5x1x100 cm3) and iron plates (6.5 cm thick) D. Kiełczewska

23. Far detector: Super-Kamiokande IV • 50 kt of water, about 13 000 PMTs • Detector well tested during over 10 years of data taking • All front-end electronics and on-line systems renovated • ready for T2K. • GPS based system selects events correlated with T2K beam spills D. Kiełczewska

24. μ e π0 The signal searched for in Super-K: Background mainly from: Also from νe beam admixture - around 0.4% νμ Super-K allows to identify with good efficiency electrons, muons and low-energy π0 D. Kiełczewska

25. Neutrino energy reconstruction in SK • Protons below Cherenkov threshold • One ring events • Muons/electrons well identified and reconstructed D. Kiełczewska

26. Expected νe appearance signal after 5 years at full intensity (750 kW) – 8x1021 pot at 30 GeV D. Kiełczewska

27. Sensitivity to ϑ13 5 years D. Kiełczewska

28. Minos 3.36x1020 pot Sensitivity to ϑ23and Δm223 νμ disappearance (OA2.5) K2K – PRD74, 072003 (2006) SK – PRL 93, 101801 (2004) MINOS – PRL 101,13180 (2008) stat. only Stat. only --90%CL --99%CL D. Kiełczewska

29. Summary • T2K – the first oscillation experiment of the 2nd generation • has just started • Primary goals: • determination of ϑ13 • better precision of ϑ12 and Δm223 • First beam commissioning has been successful • Most of ND280 components installed and commissioned • first neutrino interactions recorded in INGRID • Super-K ready and waiting for beam events • Physics data taking starts > Jan. 20, 2010 essential for CPV studies in lepton sector stay tuned D. Kiełczewska