Introduction to the Neutrino Factory

Transcription

1 Introduction to the Neutrino Factory DPNC - Université de Genève CERN - AB/ABP Division

2 Neutrino oscillation Observation: ν into another ν of different flavour Results: NEUTRINOS HAVE MASS MASS STATES FLAVOUR STATES Parameters: 3 masses Two m 2 differences Three mixing angles One delta phase = ν ν ν ν ν ν δ δ τ µ c s s c c e s e s c c s s c i i e

3 Mixing described by Neutrino Oscillations ν α For 3-flavour eigenstates U is Maki-Nakagawa-Sakata (MNS): = i U αi ν i U = c23s s23s c c iδ 13s23c12e iδ s13c23c12e s c 23 s c c 12 c 13 s s 13 s 12 s c s s e 12 iδ e iδ s 13 c c e iδ s c parameters: 3 mixing angles - θ 23,θ 12 and θ 13 CP-violation angle - δ 2 mass differences - m 2 23 and m Transition probability: P( ν ν ) = e µ sin 2θ 13 sin θ23 sin 4Eν m 2 L

4 Three family oscillation Atmospheric Neutrinos Phase δ CP Solar Neutrinos ν e 1 ν = 0 ντ c c s 0 iδ µ c23 s c12 iδ s23 c23 s13e 0 c s e s 0 ν1 0 ν 2 1 ν 3 Super-K atm. P(ν µ ν µ ) Maximal mixing m ev 2 L/E = 1 GeV/500 km Limit from CHOOZ Goal of next generation of neutrino-beam If θ 13 is zero, IMPOSSIBLE to observe CP violation SNO P(ν e ν x ) Large Mixing (LMA) Kamland L/E MeV/ m

5 Two friends for Nufact SNO: D 2 O detector Non-ν e flux in solar neutrinos Kamland: ν e disappearance from Nuclear Reactor LMA solution for solar neutrinos

6 THE last results The LMA solution for solar neutrinos is confirmed The L/E oscillation pattern is confirmed G.Fogli et al., PR D66, ,(2002)

7 B.Kaiser

8 Road Map Experiments to look for θ 13 Look for ν µ ν e in ν µ beam (ICARUS, MINOS) Off-axis beam (JHF-SK, off axis NUMI) Low energy SuperBeams Experiments to look for CP/T violation or for θ 13 (if too small) Beta-beams (combined with SuperBeam) 6He 6Li+ ν + e 18 e Ne 18F + νe Neutrino Factory µ + e + + νe + ν µ + e+

9 Sensitivity of Nufact 5 o 0.1 o 1 o 2.5 o 13 o

10 JHF ready in 2007 (0.77MW) Construction 2001~2006 (approved) (60km N.E. of KEK) Super Conducting magnet for ν beam line POT(130day) 1 year Near ν 24 Aprile 2003 DPNC

11 Far Detectors 1 st Phase (2007~, 5yrs) Super-Kamiokande(22.5kt) 2 nd Phase (201x~?) Hyper-Kamiokande(~1Mt) 48m 50m 500m, Total mass = 1 Mton

12 Proposal for a CERN - Super Beam

13 Nufact CERN layout

14 Nufact FAQ Why neutrinos from stored muons: Pure ν µ, ν e beam Switching the helicity by switching the muon sign Hope for a muon collider (may be one day ) Why high energy? High cross section neutrino interaction Small E/L (50GeV/3500 km) Why so many neutrinos? Is there someone that can do better before? See the roadmap

15 Beam Composition Nufact Beam WANF Beam The scales are different!

16 Energy and flux specs Physics at far detector NuFact near detector µ decay/year ν CC evt ν CC evt. per kg-year Minos near detector pot/year ν CC evt ν CC evt. per ton-year

17 The Holy Grail: any leptonic CP violation? P( ν P( ν e e ν ) µ ν ) µ + P( ν P( ν e e ν ) µ ν ) µ = A CP 2 sinδ sin( m12l / 4E) sinθ sinθ + Solar terms CP is observable IF: sin 2 θ 12 and m 2 12 are large (LMA) and sin 2 θ 13 small (but not too small ) Appearance experiment: P(ν e ν µ ) P(ν e ν e ) is T invariant CP is conserved (CP not observable from solar or reactor neutrinos)

18 Physics at a Nufact Measure θ 13 via P(ν e ν µ ) with a precision of 10-3 or setting a limit to 10-6 Determine via MSW the sign of m 2 Discover and measure the CP violation in the leptonic sector (phase δ) P(ν e ν µ ) P(ν e ν µ ) Need of high energy ν e : µ + e + + ν e + ν µ

19 10 16 p/s µ + e + + ν µ +ν e µ/yr ν e /yr ν µ /yr ν µ µ + Oscillation ν µ µ Wrong Sign muons

20 2.2 GeV Superconducting Proton Linac High Power 4 MW Rep. Rate 50 Hz p/pulse spaced by 22.7 nsec (44 MHz) Accumulator ring to reduce the pulse length CERN interested at least in the low energy part for the LHC upgrade and the improvement of CNGS

21 Accumulator and Compressor Accumulator Macrobunch with internal 23 ns structure (44 MHz) MUON BUNCHES KEEP THIS STRUCTURE Macrobunch Rep. rate: 20 ms (50 Hz) Compressor Microbunch length reduction to from 3.5 ns to 1 ns Time spread due to Pion decay 1 ns

22 PDAC time scheme 44 MHz structure 50 Hz

23 Proposed site Old ISR tunnel, site of accumulator + bunch compressor Radius = 50 m 24 Aprile 2003 DPNC

24 Target: Target Nufact Mercury: Z = 80 short target Liquid easy to replace (v // 20 m/s) Dimensions: L 30 cm, R 1 cm 4 MW of proton into a pint of beer 4 MW = 40000

25 Target experiment Measurements of Hg explosion speed Speed of protons >> Speed of sound Maximum v 20 m/s v // 3 m/s 1 cm Protons

26 Jet test a BNL E-951 Event #11 25 th April 2001 Protons P-bunch: Hg- jet : ppb 100 ns t o = ~ 0.45 ms diameter 1.2 cm jet-velocity 2.5 m/s perp. velocity ~ 5 m/s K. Mc Donald, H. Kirk, A. Fabich Picture timing [ms] Aprile 2003 DPNC

27 The Harp experiment Hadron production cross section measurement

28 Protons 12 GeV Be target Front view Top view Side view 24 Aprile 2003 DPNC

29 Magnetic horn Current of 300 ka Protons Hg Target π B 1/R To decay channel B = 0

30 First piece of Nufact Merci à l atelier du CERN

31 Decay channel Geometry Solenoid B=1.8 T, L=30 m π Life Time 18 p=400 MeV/c Huge Energy spread Huge velocity spread LEP σ E /E 10-3 NF σ E /E 2 Debunching Beam type β 0.8 E-t correlation Energy (GeV) Energy spread reduction needed 30 m π µ Time (arb.)

32 Nufact CERN layout

33 What is a Phase Rotation? Aim: Reducing the energy spread of a non-relativistic beam How: series of RF cavities that - accelerates low-energy particles - decelerates high-energy particles

34 Phase rotation example 100 E 300 MeV MeV 300 E = 200 ± 50 MeV RF cavities: 2 MV/m 44 MHz L = 1 m B = 1.8 T time

35 88 MHz cavity prototype

36 Cooling: the problem (transverse phase space) Problem: µ Beam pipe radius of storage ring P or x and x reduction needed: COOLING Accelerator acceptance R 10 cm, x 0.05 rad Accelerato 200 MeV π and µ after focusing

37 Ionization Cooling : the principle Liquid H 2 : de/dx sol Beam H 2 sol rf RF restores only P // : E constant

38 Cooling : the channel 1) Cooling I : x reduction 3) Cooling II : x reduction 2) Focusing : a) Needed when x reduction comparable with multiple scattering b) same rotation center for the spiral motion. (Rematching) Cooling works best with high x 24 Aprile 2003 DPNC x' f - x' = i E E f i + ϑ ϑ = 13.6MeV x 0 βpc X 0 Heating term H 2 has X 0 = 8.9 m 0

39 Cooling: the results IN Results: phase space density increased by 16 (Cooling rate for MICE: 16%) OUT

40 Channel engineering design

41 MICE: Muon Ionisation Cooling Experiment Proposal to be submitted to RAL before end of the year

42 Accelerator and Particle physics together Example of cooling SciFi Tracker TPG Tracker

43 Mice roadmap (at RAL?) µ - STEP I: 2004 STEP II: summer 2005 STEP III: winter 2006 STEP IV: spring 2006 STEP V: fall 2006 STEP VI: 2007

44 Nufact CERN layout

45 Storage ring Two straight sections pointing to two detectors Two possible shapes triangle bow tie Lattice design for beam divergence x =1/10βγ ν beam divergence dominated by µ decay θ=1/βγ =m µ /p µ = 2mrad (@ 50 GeV) 25% useful decays per direction

46 Technical problems Could you imagine a screw driver falling down from here? 14

47 Nufact CERN layout

48 Around Europe... First possible location: Gran Sasso 732 km Second location: 3500 km away best Candidates: Svalbards (Norway) Gran Canaria (Spain)

49 Where do you prefer to take shifts?

50 Why two locations? Fit of θ 13 and δ a the same time No sensitivity at 732 km Better to combine with 2810 km From P. Hernandez 24 Aprile 2003 DPNC

51 But not too far: no CP sensitivity L = 7332 km From P. Hernandez

52 The world as playground

53 Iron calorimeter Magnetized Charge discrimination B = 1 T R = 10 m, L = 20 m Fiducial mass = 40 kt Far Detector Baseline 732 Km 3.5 x Km ν µ CC ν e CC ν µ signal 1.2 x x x x x 105 Events for 1 year

54 General Considerations The neutrino factory golden-measurement is the CP violation. Super-Beam+Beta-Beam are competitive in various ways, including T violation! (M. Mezzetto, NNN02) δ = 90 deg 99%C.L. Curves

55 Last question: about financing? For the time being our situation is not so good. BUT.. Some ideas are developing

56 Reserve

57 Total flux of 8 B neutrinos

58 SNO detector Aim: measuring non ν e neutrinos in a pure solar ν e beam How? Three possible neutrino reaction in heavy water: 1000 ton of D m diam PMTs

59 SNO: the Puzzle solution SNO Day and Night Energy Spectra Alone Combining All Experimental and Solar Model information LMA (Large Mixing Angle) is the preferred solution

60 Usual attitude for LSND

61 Summary of experimental results Good news: LMA solar solution still in good shape To be confirmed by KAMLAND SNO data taking going on Super-K rebuilt in short time

62 sin 2 2θ CHOOZ <0.14 <0.14 <0.14 <0.14 <0.14 <0.14 MINOS <0.085 <0.06 <0.049 <0.042 CNGS* <0.067 <0.047 <0.039 CNGSx1.5* <0.056 <0.039 <0.033 Low energy CNGS? <0.040 <0.028 JHF-SK <0.013 Indication of time-line P. Migliozzi *Designed for ν τ appearance

63 The BETA-BEAM 1. Produce a Radioactive Ion with a short beta-decay lifetime 2. Accelerate the ion in a conventional way (PS) to high energy 3. Store the ion in a decay ring with straight sections. 4. It will decay. ν e (ν e ) will be produced. Muons: Γ~500 E 0 ~34 MeV QF~15 - SINGLE flavour - Known spectrum - Known intensity - Focussed - Low energy - Better Beam of ν e (ν e ) 6 He Beta-: Γ~150 E 0 ~1.9 MeV QF~79 18 Ne Beta+: Γ~250 E 0 ~1.86 MeV QF~135 The quality factor QF=Γ/E 0 is bigger than in a conventional neutrino factory. In addition, ion production and collection is easier. Then, X more time to accelerate. 24 Aprile 2003 DPNC

64 The Acceleration principle ISOL Target and ECR Linac Cyclotron Storage Ring PS SPS Decay ring/buncher Bunch rotation is the crucial issue for atmospheric background control! Studies are made on EXISTING CERN machines. Why? Much more detailed knowledge exists, the best way to identify possible problems and limitations. R=300 m 2500 m

65 channel at neutrino factory A. Donini et al High energy neutrinos at NuFact allow observation of ν e ν τ (wrong sign muons with missing energy and P ). UNIQUE Liquid Argon or OPERA-like detector at 3000 km. Since the sinδ dependence has opposite sign with the wrong sign muons, this solves ambiguities that will invariably appear if only wrong sign muons are used. ambiguities with only wrong sign muons (3500 km) equal event number curves muon vs taus associating taus to muons (no efficencies, but only OPERA mass) studies on-going

66 Why so far? 2.50E-02 Earth diameter: Vertical storage ring? Vac. Oscill. Prob. 2.00E E E E-03 E = 1GeV E = 30 GeV 0.00E Distance L (km)

67 Degeneracies Degeneracy: 2 or more parameter sets fit the same data Three types, all of which can effect measurement of δ & θ 13 : (1) ( δ, θ ) ( δ ', θ ) 13 ' 13 (2) m m23 (3) θ 23 π θ 2 23, θ 23 π 4 (1) (, δ ') P ( θ δ ) P = ν ν ' 13, e θ µ 13 ν eν µ (, δ ') P ( θ δ ) P = ν ν ' 13, e θ µ 13 ν eν µ θ 13 =8 o, δ=-90 o, 0 o, 90 o, 180 o 24 Aprile 2003 DPNC

68 θ 13 large δ ' π δ, θ ' θ Degeneracies + cosδ cotθ sin θ12 NB depends on L/E possible solutions 2 2 m 13L m12l cot 4E 4E Two baselines and E-dependence at NF NF + SB combination Two off-axis detectors Mena Huber/Mena Whisnant ν e ν τ as well as ν e ν µ Meloni

69 Degeneracies Mena NuFact at 2810km + SB at 130KM large NuFact at 732km + SB at 130KM small 24 Aprile 2003 DPNC

70 ν e appearance in JHF-Kamioka (phase 1) µ e π 0 Backgrounds 1.8 events 9.3 events 11.1 events Signal sin 2 2θ13=0.1, m 2 = ev 2 (5 years running) 24 Aprile 2003 DPNC

71 Europe: SPL Frejus CERN Geneve 130km CERN 2.2GeV, 50Hz, 2.3x10 14 p/pulse 4MW Now under R&D phase 40kt 400kt Italy 24 Aprile 2003 DPNC

72 SPL neutrino beam

73 CP δ and θ kt Detector 400 kt Detector Running time: 10 y antineutrinos 2 y neutrinos