The Neutrino Physics at Accelerators: the High Intensity Frontier

Transcription

1 Feb. 23, 2005 Neutrino Telescopes 2005 at Venice The Neutrino Physics at Accelerators: the High Intensity Frontier T. Nakaya (Kyoto Univ.) 1

2 1. Introduction ±Δm 23(13) 2 θ 13 Proton Decay CP 2

3 High Intensity Proton Accelerators Power (MW) Energy (GeV) Intensity (10 12 ppp) Rep. rate (Hz) KEK-PS AGS FNAL-MI SPS J-PARC Super-AGS FNAL-PD SCRF linac SPL J-PARC Upgrade 4 50 Not the construction stage yet, but R&D stage. 3

4 High Intensity Neutrino Beams <Eν> (GeV) L (km) #CC ν/kt/yr L/L osci.* f(ν e K2K ~1% NuMi-MINOS % CNGS % T2K-I ~ % NuMi-NOνA ~ % Super AGS-VLBL % T2K-II ~ % SPL % β beam** π 2 E υ (*) L osci. 2 = w/ Δm 232 = ev Δm 23 (**) γ=150, 6 He ( ν e ) Higher γ option is under consideration. 4

5 Detectors for neutrino experiments Water Cherenkov Detector T2K Super-K( Hyper-K ) BNL-VLBL (Very Long BaseLine) UNO SPL-Frejus UNO β-beam (low γ option) Lq. Ar TPC or other magnetized detector ν-factory β-beam (high γ option) Full Active Scintillator Detector NOνA 5

6 2. T2K Experiment -II Kamioka Construction started in 2004 The experiment will start in km <Eν>~0.7GeV Tokai Super-Kamiokande ~1Mton Hyper-Kamiokande (201x?) J-PARC Upgrade to 4MW 6

7 T2K Measurements ν μ ν e ν τ ν 3 Oscillation Probabilities when θ 23 : ν μ disappearance P νμ ν x θ 13 : ν e appearance 2 P sin θ sin νμ ν e 1 cos 4 ~1 ~0.5 θ sin 2 2 2θ 2θ Δm sin sin << Δm23 Δm ( Δ m L / E ) 23 ( Δ m L / E ) 23 ν 2 ν 1 ν common ν Δm 2 atm Δm 2 sun δ : CP violation (T2K-II) A CP = P( ν P( ν μ μ ν ) e ν ) + e P( ν P( ν μ μ ν e) ν e) ~0.18 Δm [ ev (sin] L 2 [ 2θ km 13 ] =0.1) sin 2θ ~0.58 E[ GeV (sin ] 2 2θ 13 =0.01) sinθ sinδ 7

8 T2K Strategy Intense ν beam J-PARC High Quality ν beam T2K Off-axis ν beam Gigantic ν detector Super-K (Hyper-K) 8

9 J-PARC Neutrino Facility J-PARC Construction 2001 ~ 2007 ν beam construction 2004 ~ GeV Transport line (Super-cond. Mag.) Target station 8 bunches/~5μs 3.3x10 14 proton/pulse 3.64 sec cycle 1yr POT (130 days) Decay volume Near detectors (280m) 9

10 J-PARC Construction Under Construction ν beam-line decay volume 10

11 Off-axis ν beam Super-K. Tuned at oscillation maximum TargetHorns Decay Pipe θ OA2 OA0 Decay Kinematics OA2.5 OA3 Quasi Monochromatic Beam Statistics at SK (OAB 2.5 deg, 1 yr, 22.5 kt, 40 GeV protons) ~ 2200 ν μ tot ~ 1600 ν μ CC ν e ~0.4% at ν μ peak 11

12 Measurement of θ 23, Δm 23 2 Use 1 ring μ-like events (= Quasi-Elastic enhanced sample) to reconstruct neutrino energy. ν ν μ +n μ + p θ μ p μ - (E μ, p μ ) 5 years No oscillation ~ OA 2.5 deg. ~ Δm 2 = 2.5 x10-3 ev 2 Δm 2 = 2.0 x10-3 ev 2 non-qe rec. Eν (GeV) rec. Eν (GeV) rec. Eν (GeV) (assuming sin 2 2θ 23 =1.0) 12

13 (/50MeV/22.5kt/5yr) Oscillation parameter fit Input: sin 2 2θ 23 =1.00 Δm 2 = 2.7 x10-3 ev 2 ALLCHAN Non-QE Eν rec (GeV) ratio Δm 2 (x10-3 ev 2 ) Ratio of E ν to non-oscillation Eν rec (GeV) sensitivity (1.0, ) sin2 2θ 1σ 90% CL 99% CL 13

14 T2K-I sensitivity with systematic errors normalization non-qe/qe ratio E scale Spectrum shape Spectrum width ( 5%) ( 5%) ( 2%) (20%) ( 5%) δ(δm 2 23 ) < ev 2 δ(sin 2 2θ 23 )~0.01 Current knowledge: δ(δm 2 23)~1x10-3 ev 2 Current knowledge: δ(sin 2 2θ 23 )~0.1 True Δm 232 (10-3 ev 2 ) True Δm 232 (10-3 ev 2 ) 14

15 θ 13 measurement (ν e appearance search) sin 2 2θ 23 =1and δ=0 are assumed. Signal: 1ring e-like event (CC QE sample) Background: beam ν e contamination (0.4% of ν μ ) mis-reconstructed π 0 event e x0.4% ν μ ν e π 0 15

16 #events (/22.5kt/5year) Background Suppression (Δm 2 =2.5x10-3 ev 2,sin 2 2θ 13 =0.1) ν μ BG ν e BG ν e signal 1. FCFV, E vis. >100MeV 2. single ring 3. e-like PID 4. no decay-electron <E ν rec <0.85GeV 6. cosθ νe < M π0 <100MeV/c 2 (π 0 fitter) 8. ΔL<80(π 0 fitter) ν e signal ν e +ν μ backgrond (ν μ backgrond) Event Selection E ν rec (GeV) 16

17 θ 13 Sensitivity (w/ δbg sys =10%) Δm 2 (ev 2 ) %C.L. sensitivity x20 CHOOZ excluded sin 2 2θ Sensitivity versus time δbg=20% δbg=10% δbg= 5% T2K-I T2K-II sin 2 2θ Year 17

18 CP violation search (T2K-II) (Note: Old study with 2 off-axis) Flux ν μ -15%@peak CC interaction cross section difference ν μ ν μ Sign flip by change of horn polarity POT/yr (1st phase) Wrong sign BG ν μ 18

19 Expected signal and Background ν μ :2yr, ν μ :6.8yr 4MW (J-PARC upgrade) 0.54Mt (Hyper-K) signal Δm 212 =6.9x10-5 ev 2 Δm 322 =2.8x10-3 ev 2 θ 12 =0.594 θ 23 =π/4 θ 13 =0.05 (sin 2 2θ 13 =0.01) background δ=0 δ=π/2 total ν μ ν μ ν e ν e ν μ ν e ν μ ν e

20 CP sensitivity (3σ) JHF-HK CPV Sensitivity sin 2 2θ CHOOZ excluded sin 2 2θ 13 <0.12@Δm 312 ~3x10-3 ev no BG 0.04 signal stat only 0.02 stat+2%syst. stat+5%syst. (signal+bg) stat only JHF 3σ discovery stat+10%syst sinδ 3σ CP sensitivity : δ >20 o for sin 2 2θ 13 >0.01 with 2% syst. 20

21 T2K Strategy Update Study ν beam property Study ν interactions Intense ν beam J-PARC High Quality ν beam T2K Off-axis ν beam Gigantic ν detector Super-K (Hyper-K) 21

22 New near neutrino detector for T2K UA1 Magnet is proposed by Euopean collaborators. (Italian group takes a responsibility.) Muon range detector EM calorimeter π0 detector FGD FGD TPC The detector is under DESIGN. FGD: Fine-Grained Detector 22

23 T2K collaboration Canada: TRIUMF, U. Alberta, York U., U. Toronto,U. Victoria, U. Regina China: IHEP(Inst. Of High Energy Phys.) France: CEA Saclay Italy: U. Roma, U. Bari, U. Napoli, U. Padova Japan: ICRR, U. Tokyo, KEK, Tohoku U., Hiroshima U., Kyoto U., Kobe U., Osaka City U., U. Tokyo, Miyagi U. of Education Korea: Seoul National U., Chonnam National U., Dongshin U., Kangwon U., Kyungpook National U., KyungSang National U., SungKyunKwan U., Yonsei U. Poland: Warsaw U. Russia: INR Spain: U. Barcelona, U. Valencia Switzerland: U. Geneva UK: RAL, Imperial College London, Queen Mary Westfield College London, U. Liverpool USA: UCI, SUNY-SB, U. Rochester, U. Pennsylvania, Boston U., CSU, Duke, Dominguez Hills, BNL, UCB/LBL, U. Hawaii, ANL, MIT, LSU, LANL, U. Washington 12 countries, 53 institutions ~150 collaborators (not incl. students) 23

24 Flux (a.u.) 0.1 Near Detector measurements SK ND280m Flux (a.u.) 0.1 SK ND280m Flux (a.u.) 0.1 SK ND280m 0.05 center-50cm 0.05 center 0.05 center+50cm Eν (GeV) OA ND =1.9 CC-QE: ν + n μ+ p CC-1π: ν + n(p) μ+ n(p) + π + NC-1π 0 : ν + n(p) ν+ n(p) + π Eν (GeV) OA ND = Eν (GeV) OA ND =2.1 ν e + many other channels. With ~5% precision 24

25 Far/Near ratio uncertainty is not large! p π ν OA 2 deg. ND SK 280m 295km 2.5 MARS FLUKA = [Far/near ratio] From MC simulation The Difference of Far/near ratio is ~1.9±0.4% (Energy range:0.4~1.2[gev]) E ν [GeV] Double ratio (FLUKA/MARS) Thanks to off-axis Narrow Band axis Narrow Band ν Beam Eν[GeV] 25

26 Improve our knowledge of ν interaction. A Near Neutrino detector provides essential information for long-baseline experiments. K2K-SciBar Extruded scintillator Some results are expected from K2K before T2K. ν 3m 3m CHORUS EM calorimeter provided by Italy/Rome group ν γ γ π 0 p NCπ 0 e CCQE nonqe 1.7m e e ν e 26

27 2km Intermediate Detector p π ν off-axis on-axis 0m 140m 280m 2 km 295 km Though it is not approved yet, it will be essential to search for CP violation with the systematic precision of 2%. 27

28 The experiments sensitive to the sign of Δm 2. Largest asymmetry for normal vs inverted Mass hierarchy at larger angles NOνA Duty cycle is tiny (10μsec/1.8sec) So detector can be at surface of Earth Site that maximizes matter effects is Not optimal for θ 13 but Mass Hierarchy Determination is unique to NOνA D. Harris (FNAL) at NuFact04 28

29 BNL very long baseline Homestake 2767 km Henderson Soudan 2540 km 1712 km BNL S. Kahn (BNL) at NuFact04 29

30 5. Summary Accelerator neutrino experiments including K2K and MINOS provide essential information for neutrino mixing and mass. The next generation experiments with a high intensity accelerator are sensitive to δsin 2 2θ 23 ~1%; δδm 2 < ev 2 sin 2 2θ 13 < 0.01 With a gigantic (100k~1Mtons) detector, the experiment has the sensitivity to the CP violation. δ<20 for sin 2 2θ 13 >0.01 The experiments sensitive to the sign of Δm 2 is also studied (not T2K). We are also looking forward an expected phenomena in the experiments. 30