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Experiments to detect q 13

Experiments to detect q 13. M.Apollonio Universita’ di Trieste e INFN. Layout of the talk. q 13 and motivations to its measurement Chooz limit Appearance and disappearance experiments Accelerators (A) Nuclear Reactors (R) (A) Approved projects (Phase I) Phase II Phase III (R)

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Experiments to detect q 13

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  1. Experiments to detect q13 M.Apollonio Universita’ di Trieste e INFN IFAE 2004, Torino

  2. Layout of the talk • q13 and motivations to its measurement • Chooz limit • Appearance and disappearance experiments • Accelerators (A) • Nuclear Reactors (R) • (A) • Approved projects (Phase I) • Phase II • Phase III • (R) • Double-Chooz and similar IFAE 2004, Torino

  3. q13 • Scenario: MiniBoone disfavouring LSND • “standard picture” • 2 Dm2ij (Dm212, Dm223) indipendent • 3 mixing angles (q12, q23, q13) • 1 CP phase • Mixing Matrix PMNS • 1-2 solar mixing • 2-3 atmospheric mixing • 1-3 o e3 mixing: q13 describes oscillations ne at the atmospheric frequency • dCP introduces CP violation effects Current experimental results: • Dm223 ~ 2x10-3 eV2 • Dm212 ~ 7x10-5 eV2 • Dm223 >>Dm212 • q12~35o • q23~45o IFAE 2004, Torino

  4. Why measuring q13? • The least known among the parameters in PMNS • Coupled to eid (Ue3) • q13>0would allow to access d • CP violation in the lepton sector IFAE 2004, Torino

  5. What do we know about q13 today? • q13 must be small (maybe null) • The best limit up to date comes from the reactor experiment CHOOZ: • q13 < 10o-17o • (1.3x10-3<Dm232<3x10-3) [J.Bouchez, NO-VE 2003] [CHOOZ coll., Eur.Phys.J.C27(2003),331-374] IFAE 2004, Torino

  6. 3 families scenario:appearance experiments Accelerators NB: P sensitive to d (correlated with q13) • a should be considered • sign(Dm213) is present in A [P.Migliozzi, F.Terranova arXiv:hep-ph/0302274] IFAE 2004, Torino

  7. Accelerators • general concept: conventional beam • Broad band (BBB) • Narrow band (NBB) • Super Beam (SB) • Off-Axis Beam (OA) • b-Beam (bB) • Neutrino Factory (NF) IFAE 2004, Torino

  8. Main backgrounds: • Initial ne contamination in the beam • p0 production (NC) • Near/Far detection (A) General concept Production & focusing oscillation decay (had+m stop) target detection (m,e,t) p nm ne p,K nm m- e- CC nm(>99%) ne nm e- m- ne(<1%) IFAE 2004, Torino

  9. (A)-SB • It is a conventional proton beam whose power is of the order of MW • Produces nm (nm) • Proton-driver: technically feasible • PB: target • Sol.: R&D Proposed rotating tantalum target ring IFAE 2004, Torino

  10. q Decay Pipe Horns Target (A)-OA • Detector laying out of the main beam axis • Kinematics  n beam energy almost independent from Ep • Monochromatic  suppresses the high energy tails • You pay it in terms of flux • Examples: En at 2 different energy scales for Ep at several OA angles IFAE 2004, Torino

  11. (A)b-Beams[P.Zucchelli, Phys.Lett. B532:166,2002] • Original solution: radioactive ions with short lifetime • acceleration • storage • decay • Es.: b- (6He) ne, b+ (18Ne)  ne IFAE 2004, Torino

  12. (A)-NF IFAE 2004, Torino

  13. Experiment Power (MW) E (GeV) L (km) detector Sens to q13 Starting date MINOS 0.4 3 730 Calorimeter 5o 2005 Phase I: use an existing facility and approved projects (q13>5o) OPERA 0.17 20 732 Emulsion 7o 2006 Phase I ICARUS 0.17 20 732 L-Ar 5o 2006 NuMI-OA 0.4 2 700/900 Fine grained calorimeter[20kT] 2.5o 2008 ? Phase II: go for 1st generation of Super-Beams (q13>2.5o) Phase II T2K (OA) 0.8 0.7 295 WC (SuperK) [20kT] 2.3o 2009 T2K-II (OA) 4.0 0.7 295 WC (HyperK) [500kT] 1o 2020 ? Phase III: 2nd generation of Super-Beams (q13>1o) [Phase IV: Neutrino Factories see relevant talk] Phase III SPL-SB 4.0 0.27 130 WC/L-Ar [500kT] 1o ~2015 b-Beam 0.2 0.3-0.6 130 WC/L-Ar [500kT] 0.5o 2018 ? (A) Experiments[J.Bouchez, NO-VE 2003] IFAE 2004, Torino

  14. (A) Experiments (cont’d) • Requirements for Super-Beams (nmne appearance case) • Beam side: • Low ne contamination • Good knowledge of ne/nm • Good understanding of the beam (near to far) • Detector side: • Good e- efficiency • Good p0 rejection • Good understanding of bkg IFAE 2004, Torino

  15. ~1 Which energy? • Low or high? • Focalisation of neutrinos ~g2~E2 • Solid angle factor @ L ~1/g2~1/E2 • s(n) ~g~E • p flux ~1/g~1/E • The 0th order approximation cannot help that much in the choice • Other considerations mandatory IFAE 2004, Torino

  16. WC technique gives a good p0 (NC) vs e- separation (2-ring vs 1-ring) Less ne (below K threshold) Fermi momentum  poor E resolution No matter effects Better use fine grained detectors or L-Ar TPC Need good p0 rejection More ne bkg Better resolution in E Matter effects can arise  sign(Dm213) Low (E<1GeV) or High (E>1GeV) ?[choice related to bkg considered] intrinsic ne contamination and p0 mimicking e- caveat: stay below t threshold IFAE 2004, Torino

  17. Underground or not? • In principle not: just a matter of choosing the right (low) duty cycle [phase II, 20 kton] • BUT it is a must if your detector is “multi-purpose” (e.g. searching for other effects like proton decay) [phase III, 500 kton] IFAE 2004, Torino

  18. Near/Far • Best way to determine ne bkg: measure it at a near location (before oscillation) • Try to ensure equality of conditions between near and far detectors: i.e. same beam, same target nuclei (cross sections and p0 production do depend on nuclei) • Near detector sufficiently far from the source  point-like assumption (~ 2 km) • If you go closer then the source is not point-like anymore • Near detector able to understand the different n interactions (QE/non-QE) • Ideally TWO near detectors (~300 m, ~2 km): • One giving a clear clue about n interactions • The other as much as identical to the FAR detector IFAE 2004, Torino

  19. Beam Near(~2km) Far(700km) N F Beam V-Near(300m) Near(~2km) Far(700km) N1 VN F N2 Near/Far (cont’d): strategies for beam understanding • Cheap solution: • N sees a point-like source • F and N use the same detection technique (1/L2 law) • Good for discovery though it does not allow a precise measurement of q13 • “Pricey” solution: • VN N1: similar detection techniques allowing beam understanding • N1  N2: different in s(n) and detector performances  can be compared • F and N2 using the same detection technique • Should be optimal for high statistics phase III where you want to reduce systematics (less dramatic for phase II) IFAE 2004, Torino

  20. 800 CC νμ　/ year Eπ vs. Eν 2200 CC νμ　/ year OA1° 50 kton Water Cherenkov 0.0゜ OA2° 1.0゜ OA3° 1.5゜ 2.0゜ 3.0゜ 5.0゜ Max. osc. energy for 3×10-3eV2 T2K [I/II] • OA: q~2o, JHF-PS(50 GeV p) SK[I]  HK[II] • Maximize the potential discovery (on-peak)  d,q13,sign(Dm132) • L~295 km, <E>~0.76GeV  on peak • |A|~5x10-2 matter effects negligible • Phase I: use SK detector (20 kton) • Phase II: go for a more ambitious device  HK (500 kton) IFAE 2004, Torino

  21. p p Muon detector n Water Cherenkov detector Fine grained scintillater detector 8m 0m 140m 280m 2 km 295 km ν μ ν ν beam 8m 15.2m 5m Total mass : 1000ton Fid. Mass : 100ton IFAE 2004, Torino

  22. OAB (2degree) nm Signal for non-zero θ13 in JHF-SK (νμ→νe) BG (NC π0 ….) 0.2% m-decay ne SK-90%CL allowed K-decay SuperKamiokande • Water Cerenkov detector • Sub-GeV  good p0/el. separation • q13: 2.5o sensitivity after 5 yrs of data taking T. Kajita, Fermilab – May 2003 IFAE 2004, Torino

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