Experimental Aspect of Neutrino Physics

Transcription

1 Experimental Aspect of Neutrino Physics K. Nishikawa Kyoto University Third International Conference on Flavor Physics National Central University Oct. 8, 005

2 1. Evidences for massive neutrinos and 3 generation frame-work. Questions to be answered by on-going experiments 3. Next generation experiments Oscillation measurments double beta decay direct measurments 4. Next to next generation (if no surprise in ~10 years) 5. Summary

3 Evidences for massive neutrinos Rate reduction L/E dependence New flavor appearance

4 Rate reductions for various Eth

5 Events/(0.05) Day Salt Phase Flux Results in SNO Fit Result AV bkg PMT+HO bkgd. External neutrons Data Neutrons CC ES R=550 cm ρ (c) Φ cc (ν e ) = 1.68 (stat.) (syst.) 10 6 cm s Φ es (ν x ) =.35 (stat.) (syst.) 10 6 cm s Φ nc (ν x ) = 4.94 (stat.) (syst.) 10 6 cm s BS05(OP) Standard Solar Model Flux Calculation: (5.69 ± 0.91) 10 6 cm s 1 Events/(0.0) Data Fit result Neutrons CC ES External neutrons cos θ (b) = ± 0.03 Appearance of non-νe components in solar neutrinos φ φ CC NC Events/(0.0107) 160 Data Fit result 140 Neutrons CC 10 ES External neutrons (a) β 14

6 Kamland L/E plot (759 days, 5m fiducial) low energy window best fit reactor + geo-neutrino model prediction Oscillation pattern with real reactor distribution Lo = 180 km is used for KamLAND There is clear Oscillatory behavior (peak and dip) oscillation parameter is determined.

7 KamLAND best-fit (rate + shape) Solar region KamLAND + Solar assuming CPT invariance m = ev tan θ = 0.46 m = ev tan θ =

8 Atmospheric neutrinos SK-I Zenith angle distributions 1R e SK-I Atmospheric ν Full Paper hep-ex/ Y. Suzuki LP005 1R µ MR µ up-µ Number of events <400MeV 1R e >400MeV 1R e <400MeV 1R µ >400MeV 1R µ sub-g MR µ multi-g up-µ cosθ data stopping through multi-g cosθ up multi-g cosθ down PC cosθ no oscillation w/ oscillation

9 Result of L/E analysis in atmospheric ν Data/Prediction Oscillation days FC+PC Decoherence Decay L/E (km/gev) 3.4 σ to decay 3.8 σ to decoherence Events with E,L determined The first dip has been observed at ~500km/GeV This provide a strong confirmation of neutrino oscillation The first dip observed cannot be explained by other hypotheses χ Resolution Cuts vs χ (%)

10 m [ev ] m [ev ] Reduction of rate and Spectrum distortion in KK KK-I & KK-II events/0.[gev] N SK obs =108 N SK exp = 151 Entries 56 Best Fit KS prob.=5% % 90% 99% sin (θ) sin θ Eν rec [GeV] Eν rec [GeV]

11 Atmospheric neutrinos 10 - Fit for the 180 θ ν zenith and momentum bins 180 N i obs i 1 N i exp 1 i 39 j 1 N i exp i f j j N i 0 P 39 Systematic error parameters 39 j j j m Best fit (Physical Region) sin θ =1.00 m =.1x10-3 ev χ min =174.8/177dof χ =303.9 (for no oscillation) 10-3 sin θ x10-3 ev < m < 3.4x10-3 ev sin θ > 0.9 (@90%C.L.)

12 CHOOZ θ 13 Only upper limit from a reactor experiment. ν e disappearance were searched with L~1km. sin θ 13 m 3 =.0E-3eV

13 Physical quantities in 3-generation neutrinos = 3 1 CP U MNS V M ν ν ν ν ν ν τ µ e ν e ν µ ν τ Weak eigenstates m 1 m m 3 mass eigenstates = U PMNS c s s c c e s e s c c s s c i i δ δ c ij = cosθ ij, s ij =sinθ ij = e e V 1 i i CP M α α If Majorana Oscillation Only appear in L non conserv. θ 1, θ 3, θ 13 m 1, m 3, m 13

14 What we know now CHOOZ ( ) upper limit At least non-zero mass neutrino states Two of the mixing angles are large One small OR Possibility of Sterile ν depending on the validity of the LSND result

15 . On-going efforts,.

16 MiniBooNE Sensitivity to a Signal Signal Mis-ID Intrinsic ν e Δm = 1 ev Δm = 0.4 ev The LSND question will soon be resolved

17 Projected Coverage Here we see the projected limits for a null result with pot Even with pot we should still cover the entire 90% CL region from LSND at 3σ3 This sensitivity depends on understanding the background from intrinsic ν e to 10% and the background from mis-id π 0 to 5%

18 II. NuMI/MINOS Outline Physics Status Precise determination of - ν µ oscillation parameters - resolve non-maximal θ 3 mixing Search for ν e appearance Discriminate various models May 000; NuMI construction started. Dec. 004; Commissioning started Jan. 005; First event detected in ND. March 005; First event detected in FD. Now accumulating data.

19 II. NuMI/MINOS Expected Sensitivity courtesy of S.Kopp, U Texas ν µ Disappearance Resolving power of Non-Maximal Mixing Search for ν µ ν e Appearance For m = ev, sin θ 3 = % and 99% CL allowed regions compared with SK. 90%C.L. allowed; δ( m ) = ev m (ev ) Region where sin θ can be resolved as <1.0 at 90% CL. sin (θ 3 ) SK allowed (90%C.L.) sin (θ 13 ) Discoverable at 3σ CHOOZ ( m = ev ) MINOS ( m = ev ) NOvA or JHF (009+5yrs) Protons on Target ( 10 0 )

20 II. NuMI/MINOS Outlook courtesy of S.Kopp, U Texas Expect 10 0 protons delivered to the NuMI target by early December, 005. Use this data for coarse m measurement (establish LE/ME/HE beam tune). Continue running until 8 week FNAL shutdown (planned for March 06) In 006, expect significant increase in data set, precision measurements on m.

21 II.3 CNGS/OPERA Expected Sensitivity courtesy of Y. Declais, IPN Lyon Expected number of ν τ appearance events = 1.8 events at m =.4 x 10-3 ev while expected B.G. = 0.8 events Upper limit for ν τ appearance 90%C.L. sin θ 13 sensitivity sin θ 13 CHOOZ 5 years nominal 0.06 systematics Assuming: θ 3 =π/4, m 3 =.5x10-3 ev Pot(x10 19 )

22 II.3 CNGS/OPERA Status and Outlook courtesy of Y. Declais, IPN Lyon RPC; Cosmic ray test running partially Full commissioning in Jan.06. HPT; Partially installed. Full installation by the end of '06. Brick;Half completed in Oct.05 Full completion in June 06. TT; Cosmic ray test running partially Full commissioning in June 06. Unambiguous evidence for ν µ ν τ - OPERA should see ν τ within a few years. Search for ν e appearance - have enough sensitivity for study : sin θ 13 =0.06 Final count down toward May 06.

23 Summary of expectations from on-going experiments MiniBooNE 3 generation ν Mini-BooNE collaboration will report first result this year Need understanding the background from intrinsic νe e to 10% and the background from mis-id π0 0 to 5% Numi-Minos has started Non-maximal -3 3 mixing to 90%CL for certain value of θ3 ~30% measurement of m 3 sin θ 13 to 0.06 CNGS/OPERA τ appearance sin θ 13 to 0.06

24 -. Neutrino mass scale

25 Direct measurement of m νe (Weinheimer LP005) Cryo-Bolometer experiments with 187 Re m ν <15 ev (90%CL) m =- 11±07±90 ev M.Sisti et.al. NIMA50 (004)15 Mainz phase result (spectrometer) m ν <.3eV (95%CL) m = -0.6 ±.±.1eV C.Kraus et.al. Eur. Phys. J C40(005)447 Troitsk neutrino mass exp. (spectrometer) m ν <.05 ev(95%cl) m =-.3 ±.5±.0 ev

26 008 Commissioning of full setup/start of taking data

27 From Cosmology Steen Hannestad(LP005) A SELECTION OF RECENT RESULTS ON Σm ν WMAP ONLY 13 95% WMAP SPERGEL ET AL. (WMAP) % WMAP, CMB, df, σ 8, H 0 STH % WMAP, CMB, df, H 0 ALLEN, SMITH, BRIDLE % WMAP, CMB, df, σ 8, H TEGMARK ET AL % WMAP, SDSS BARGER ET AL % WMAP, CMB, df, SDSS, H 0 CROTTY ET AL % WMAP, CMB, df, SDSS, H 0 STH % WMAP, SDSS, SNI-A, H 0

28 Neutrino-less double beta decay Majorana neutrinos L non-conserving process <m ν >= U ei m i

29 Cremonesi LP005

30

31 0νββ is a unique tool to specify Absolute mass scale Majorana/Dirac Lepton number violation CP violation Majorana phase Large nuclear matrix element uncertainty One claimed evidence for 76 Ge 1-10 kg ongoing expt (NEMO&CUORICINO) GERDA Intermediate goal <0.1eV -3 00kg expt approved Ultimate ~0.01eV many proposal with various techniques (Cryogenic, material,..)

32 Other neutrino properties

33 dσ dt ( νe) = πα 1 1 E µ µ m ν e T ν Search of µ ν at low energy high signal rate & robustness: µ ν >>SM [ decouple irreducible bkg unknown sources ] T << E ν dσ/dt depends on total φ ν flux but NOT spectral shape [ flux well known : ~6 fission-ν ~1. 38U capture-ν per fission ]

34 3. Next generation oscillation experiments

35 νµ νe with m ~ ev and CP violation ν ν ν = ν ν ν τ τ τ µ µ µ τ µ ) (m ) (m ) (m U U U U U U U U U e3 e e1 e νµ νe * * * Interference CP violation supressed by small m small U e3

36 P( νµ νe ) = 4C + 8C 8C + 4S 8C S C C S ν oscillation probability S C 13 3 ( C S S 13 S S S 3 ( C S C 1 13 S 3 3 (1 S sin C cosδ S 3 1 sinδ sinφ + S Φ δ -δ, a -a for ν µ ν e S S 3 13 S al ) cosφ 4E 13 3 S 3 sinφ C 1 31 sinφ ij )cosφ C sinφ S S sinφ 1 3 S 13 L / 4E, L : flight length, m = m Many ambiguities by various terms Φ a = ij m ij i m j ρ.6 [ g / cm sinφ 1 cosδ )sin sign( m 13), m i Φ 1 S ij =sinθ ij, C ij =cosθ ij E : neutrino energy, : mass eigenvalues E ] [ GeV ] CP conserving θ 13 CP solar ν matter effect [ev ]

37 θ13 by reactor experiments

38

39 Accelerator Experiments

40 Physics Precise determination of - ν µ oscillation parameters - resolve non-maximal θ 3 mixing θ 13 measurement CP violating δ mass hierarchy determination Off-Axis smaller energy spread higher flux at osc.max. less background Status Apr. 004; ν-facility construction started. May 008; Main Ring commissioning will start May 009; ν-line commissioning will start TK/SK Outline

41 Main features of TK 1. Proper neutrino energy QE dominant Event-by event Eν reconstruction Small high energy tail small BKG in νe search and Eν reconstruction. Proper coverage of near detector(s) Minimum effects from cross section ambiguity 3. Far water Cherenkov detector has accumulated close to twenty years of experience KK has demonstrated BG rejection in νe search

42 Narrow intense beam: Off-axis beam First Application (ref.: BNL-E889 Proposal) Super-K. m =3x10-3 ev Decay Pipe TargetHorns π decay Kinematics θ ν µ flux OA OA0 Eν (GeV) OA.5 OA p π (GeV/c) Quasi Monochromatic Beam x ~3 intense than NBB Tuned at oscillation maximum Statistics at SK (OAB.5 deg, 1 yr,.5 kt) ~ 00 ν µ tot ~ 1600 ν µ CC ν e ~0.4% at ν µ peak

43 ν µ ν e oscillation probability in sub-gev neutrinos sin θ 13 =0.01 total θ 13 CP CP solar matter

44 II.4 TK/SK Expected Sensitivity Precision measurement of ν µ disappearance parameters Stat. only (OA.5 ) --68%CL ( ln L=0.5) --90%CL ( ln L=1.36) --99%CL ( ln L=3.3) Goal; δ(sin θ 3 ) ~ 0.01 δ( m 3 ) ~ % C.L.

45 II.4 TK/SK Expected Sensitivity θ 13 sensitivity m 13 [ev ] CP phase δ (degrees) δ (degree) m 13 =.5x10-3 ev m 13 = 1.9x10-3 ev m 13 = 3.0x10-3 ev sin θ 3 = 1 m 1 = 8.x10-5 ev tan θ 1 = sin θ KASKA 90% (NuFact04) CHOOZ 90% sin θ sin θ 13 >10 times improvement from CHOOZ for almost any m or δ

46 Sensitivity v.s. exposure 10% syst. err assumed on BG subtraction sin θ 13 sensitivity (90%) sintht13 sensitivity %CL Sensitivity w/ LINAC upgrade Default x Np x Np x1.5 rep x Np x rep JFY Japanese Fiscal Year (Apr-Mar)

47 II.4 NuMI/NOνA Outline Physics Precise determination of - ν µ oscillation parameters - resolve non-maximal θ 3 mixing θ 13 measurement CP violating δ mass hierarchy determination CPT test via ν µ ν µ and ν µ ν µ Super-Nova Off-Axis Schedule Apr. 005; Stage-I approval by FNAL Oct. 006; Construction be started Oct. 009; 1st 1kt-module be operational July 011; full 30kt be operational

48 II.4 NuMI/NOνA Proton and Neutrino Beams Proton Beam; NuMI upgraded 0.65MW, 6.5 x 10 0 POT/year NuMI + Proton Driver MW, 5 x 10 0 POT/year Neutrino Beam; Use existing NuMI with ME tune. 14mrad off-axis Eν ~.3GeV - 30% higher than oscillation max. - Has sensitivity to cosδ ~1% ν e contamination

49 II.4 NuMI/NOνA Detectors (NuMI tunnel) Each section is an 8-plane block (Ash River) - 1km-off-axis (14mrad) - Totally active - Fine-grained (tracking) - 30kt liquid scintillator - read out via WLS+APD 13 m 15.7m FD was on surface, but now has 3m-overburden. 15.7m 3-plane block

50 II.4 NuMI/NOνA Expected Sensitivity m 3 Precise determination of sin θ 3. 5years run w/pd achieves 0.00 near maximal mixing. sin θ 3 ν e appearance; sin θ 13 ~0.01 Mass Hierarchy δ [π] Feldman, NuSAG05 sin θ 13 sin θ 13

51 II.4 NuMI/NOνA Outlook 95% C.L. mass hierarchy ID with nd off-axis detector. Mass hierarchy solved for all δ for sin θ 13 > Many questions charged by FNAL PAC. - Answers being replied. Project team being created. Plan to start data taking (partially) in 009 May build another off-axis detector at the nd oscillation maximum. sin θ 13 Feldman, NuSAG05

52 III Summary power FD mass Baseline δsin θ3 δ( m 3) θ13 MW kton km 90%CL 90%CL KK x NuMI/MINOS x (3σ) CNGS/OPERA (90%CL) TK/SK x (3σ) NuMI/NOvA x (3σ) NuMI+PD/NOvA (3σ) TK-II/HK (3σ)

53 three ambiguities Okamura δm 13 sign of δm 13 fold ambiguity ( ) θ 13,δ MNS unobserved parameters fold ambiguity sin θ 3 value of θ 3 (octant) fold ambiguity best fit is θ 3 =45 : no octant ambiguity

54 4. Next to next if no surprise

55 Technological devlopment needed for high intensity 3.3E14 ppp w/ 5µs pulse When this beam hits an iron block, radio activity > 1000Sv/h cm 1100 o (cf. melting point 1536 o ) Material heavier than iron would melt. Thermal shock stress Eα T 3GPa (cf. stress limit ~300 MPa) Material heavier than Ti might be destroyed. Cooling power and radiation shield

56 Beta Beams Small divergence νe anti-νebeam The goal of beta beams is to produce a pure beam of either ν e s or ν e s (proposed by Zucchelli). The required steps are: Produce a Radioactive Ion with a short betadecay lifetime 1. Produce radioactive ions with lifetime ~ 1 sec. Accelerate the ions to high energy 3. Store. Accelerate the ions the in ion a storage in a conventional ring with way straight (PS) sections to 4. Detect high the energy decay ν s 3. Store the ion in a decay ring with straight sections. Since the two kinds of ν s are run separately, no magnetic field is needed in the detector. Water Cherenkov might be used. 4. It will decay. ν e (ν e ) will be produced.

57 Possible realization 1. Use 18 Ne as source of neutrinos, 6 He as source of antineutrinos. Use SPS for acceleration to high energy (γ 00) ~00 MeV ν s No π 0 BKG 3. Construct storage ring with 5T magnetic field; straight section of 36% of total length 4. The putative detector is a 600 kt water Cherenkov detector in the Frejus tunnel, 130 km away

58 Neutrino Factory The goal of a neutrino factory is to provide a source of neutrino and anti-neutrino beams that are intense, energetic, and well understood. The specific idea is to construct a muon storage ring with long straight sections and use ν s from µ decays.. There are many technical challenges. Some of the most important ones are: 1. Design of target for high power beams (few Mw). Cooling of muons (initial P T ~ 300 MeV) 3. Rapid acceleration of muons (from ~100 MeV to tens of GeV) 4. Construction of steep beam lines (tens of degrees)

59 Golden Signature The transition ν e -> ν µ is detected by observation of the wrong sign muon. Should be relatively background free. Need a detector with magnetic field.

60 CP and mass hierarchy

61 TK-II/HK upgrade enables TK/SK x TK-II; 4MW proton beam - HK; 1Mton water-cerenkov II.4 TK/SK Outlook: TK-II/HK challenge sin θ 13 ~ 10-3 down to sinδ ~ 0.3 systematic error of BG should be a few % Matter effect with ν=y, ν=6.8 y JHF-HK CPV Sensitivity sin θ 13 sin θ no BG.Ssignal stat only CHOOZ excluded stat+%syst. stat+5%syst. (signal+bg) stat only stat+10%syst sinδ sinδ TK 90% 3σ sensitivity: δ >0 o for sin θ 13 >0.01 with % syst. Or detector in Korea?

62 Proton decay limit from SK Inputs from LHC?.9x10 30 yr ( minimal SUSY SU(5) )

63 solar, reactors, accelerator θ1 θ3 θ13 CPV Mass hierarchy Direct measurement <me> > 0. ev mass scale Cosmology m ν 0νββ Majorana <me> > 0.1eV mass scale Surprise? (Charged) LFV LHC SUSY or.. Proton decay Direct evidence of GUTs