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Neutrino Oscillation Experiments with Accelerator Produced Neutrino Beams

Neutrino Oscillation Experiments with Accelerator Produced Neutrino Beams. Outline Framework and Current Situation Accelerator and Reactor Osc. Experiments Probing: Solar Neutrino (Very brief) Atmospheric Neutrino K2K MINOS CNGS LSND n m n e Region MiniBooNE. M. Shaevitz

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Neutrino Oscillation Experiments with Accelerator Produced Neutrino Beams

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  1. Neutrino Oscillation Experiments with Accelerator Produced Neutrino Beams • Outline • Framework and Current Situation • Accelerator and Reactor Osc. Experiments Probing: • Solar Neutrino (Very brief) • Atmospheric Neutrino • K2K • MINOS • CNGS • LSND nmne Region • MiniBooNE M. Shaevitz Aspen 2000 Talk Jan. 22, 2000

  2. nmne at the same Dm2 as nmnt CKM-like Mixing Matrix for Leptons Neutrino Oscillation Formalism • Most analyses assume 2-generation mixing • But we have 3-generations: ne , nm, and nt (and maybe even more ….. the sterile neutrino ns’s ) (In this 3-generation model, there are 3 Dm2’s but only two are independent.) • At each Dm2, there can be oscillations between all the neutrino flavors with different mixing angle combinations. For example:(3 sets of 3 equations like these)

  3. CP Violation in Neutrino Oscillations • Disappearance measurements cannot see CP violation effect • Very, very hard to see CP violation effects in exclusive (appearance) measurements. (From B. Kayser) • Only can see CP violation effects if an experiment is sensitive to oscillations involving at least three types of neutrinos. • All the terms (s12, s13, s23) must not be <<1 or effectively becomes only two component oscillation • For example, if s12 0 then s13 -s23  s12 + s31 + s23 0  To see CP violation must be sensitive to solar neutrino Dm2 10-4 - 10-10 eV2

  4. Phenomenological Guidance Chorus and Nomad Exps. at CERN Chorus Final

  5. Three Indications of Neutrino Oscillations • Questions: • Are all three indications really neutrino oscillations? (If so then need fourth ns) • Need to see oscillatory behavior in En or L • Need 4s measurements not 90% CL • Determine which flavors are oscillating • Which solar solution if any is correct? • Measure oscillation parameters Dm2, sin22q • Measure full lepton flavor mixing matrix

  6. Solar Neutrino Studies Future Studies: • Super-Kamiodande • Increased statistics • Lower Threshold to 4.5MeV • SNO • CC(9ev/day)/NC(3ev/day) • Flux Indep. or e  s • CC: E spectrum and D/N • Borexino • Good statistics measurement of 7Be ’s (55ev/day) • Seasonal variation if Vac. Osc. • KamLAND (Reactor Exp.) • LMA region (700 events/yr) 0.550.06 0.330.03 0.540.07

  7. KamLAND (Kamioka Liquid scintillator Anti-Neutrino Detector) • First attempt to study the solar neutrino puzzle“in the laboratory” • Start Data in 2001 • Neutrino Source: • Japan’s 51 nuclear power reactors • Distance/Energy: • ~150-200 km / ~1 MeV Dm2  10-5 eV2 • Detector: • 13m-diameter spherical balloon filled with liquid scintillator and PMT’s

  8. KamLAND Expected Sensitivity • Expected rate: • 700 antineutrinos detected per year with no oscillations.

  9. Atmospheric Neutrino Oscillation Sensitivity L = 20 km, Oscillations if Dm2 >10-2eV2 SuperK n En ~ 300 MeV - 2 GeV Earth L = 104 km, Oscillations if Dm2 > few x 10-5 eV2 10-5 10-4 10-3 10-2 10-1 Dm2 Multi-GeV Sub-GeV No oscillationsZenith angle dependenceOscillations for all angles R = 1.00.5 < R < 1.0R = 0.5 if sin22q = 1

  10. Recent Super-K Results (848 days = 52 kton-yrs) SuperK Best Fit:Dm2 = 3.510-3 eV2sin22q = 1.0a = 0.06 No Osc. nmnt

  11. Reactor Experiments Limit Atmospheric nm ne Possibilities • CHOOZ, Bugey, and Palo Verde Reactor Experiments • <En> ~ 3 MeV and L ~ 1 km  Dm2  310-3eV2 CHOOZ 99

  12. What flavors are oscillating? • Dominant nm  ne: • Ruled out by CHOOZ reactor n experiment • Sub-dominant osc. possible at the sin22q < 0.10 levelCould SuperK be seeing mixture of nm  ne at 10-4 eV2and nm  ntat 10-1 eV2 • Dominant nm  nt: • Try to isolate the ntevents? • Super-K (Soudan) has ~ 47 (4) CC nt’s in their samplebut these are hard to isolate from NC events • Dominant nm  nsterile : • nsterile has no coupling to Z0 Look for n N  n N p0 (Not easy) • Super-K p0 - like (~NC/CC) double ratio (Data/MC)Current value is 1.11  0.06  0.26(expect 1.00 for nt and ~0.8 for nsterile). • nsterile will have matter effects at cosq = -1(Dm2 dependent)

  13. Matter Effect Analysis in SuperK • Interactions with matter in earth effect nm  nsterile oscillations since nsterile has no NC interactions with quarks.

  14. KEK to SuperK (K2K) Experiment • Low energy, E>=1.4 GeV, beam sent from KEK to SuperK (250 km) • Several front detectors at 100m and beam monitors

  15. K2K Expectations and Status • Expected Event Rates for 3yrs (~1020pot): Fine-Grained Near1 kt H2O NearSuper-K nm CC 126,700 408,000 345 • nm NC 44,900 144,000 120 single p0 9,200 29,500 25 • ne CC 1,250 4,000 4 • Current Status: • Ran for 20 days in Su, 99 • Rate in front detectors close to expectation (10% low) • Observed four events in SuperK within 1ms (One in fid.vol. with low energy) • Expected five events in fid. vol. with no oscillations • Nov. 99: 1 month runFeb - Jun, 2000: 5 month run 2001-2 2003-4 • Only 90% CL regions  Need 4s to 5s

  16. The MINOS Beamline Two Detector Neutrino Oscillation Experiment (Start 2003) • Far Detector (5.4 ktons) : - 8m diameter by 1” steel plates - 4cm wide solid scintillator strips - Steel magnetized at 1.5 T Det. 2 Det. 1

  17. NuMI Beam Options • CC Events Rates in Minos 5kt detector: • High 10,000/yr • Medium 5,000/yr • Low 700/yr Rates are for 3.71020protons on target per year~ (3.51013ppp/1.9sec)2107sec

  18. MINOS Far Detector

  19. Possible MINOS Physics Measurements • Obtain firm evidence for oscillations:(Near/Far comparison reduces systematic uncertainties) • CC interaction rate and energy distribution • NC/CC rate ratio and energy distribution • Measurement of oscillation parameters, Dm2, sin22q • CC energy distribution • Determination of the oscillation mode(s) • NC/CC rate measurements • Identification of ne by topological criteria • Identification of nt by its exclusive decay modes (works best if Dm2 is relatively high)

  20. Schedule MINOS Steel Plane Prototype • Detector Hall construction in Minnesota (now - 2001) • Beam Tunnel construction at Fermilab (2000 - 2002) • Far Detector construction (2001 - 2003) • Start data run (2003) Undergroundbreaking at Soudan; July 20, 1999

  21. MINOS Dm2 Sensitivity 90% CL 3.5s

  22. 90% CL Contours Dm2(eV2) 0.005 0.003 0.002 MINOS Measurement Capability

  23. 4s Separation Region MINOS Oscillation Mode Sensitivity( Discriminate nm vs. nmsterile ) • Use CC/NC Ratio to distinguish between oscillations to ntor nsterile • For nm , CC production of t’s will look like NC ~80% of the time CC/NC  down • For nmsterile , both CC and NC will be suppressed. CC/NC stays ~ constant

  24. Is the Next Step a nt Appearance Experiments? • Will MINOS and/or SuperK decisively determine oscillation mode corresponding to the atmospheric deficit? • If not, then may need to observe nt directly • Need fine grained detector to see indications of t decay • Challenge: Need to reach large fiducial mass of order 1 kton • Emulsion (combined with scintillator or chambers) • Problem: Finding and scanning events difficult • Fine-grained calorimeters, i.e. Liquid-Argon • Indirect missing energy/ptrans signals difficult to isolate. • These new detectors may also be able to probe nmeat low Dm2 and low sin22q • Sensitive to other elements of the lepton mixing matrix

  25. CERN to Gran Sasso n Osc. Program (CNGS) • CERN has approved a program for a neutrino beam from CERN to Gran Sasso • Beam similar to Minos with nt rate factor of two lower • Unlikely that a near detector hall would be built • Emphasis on appearance experiments with ntand ne identification • Opera Experiment: Emulsion detector • ICANOE Experiment: Liquid argon plus fine grain calorimetry

  26. CERN to Gran Sasso Beam • Uses 400 GeV protons on target: • <En>  17 GeV • Distance  750 km • ~ 4.5  1019 protons on target/yr • Event rate at Gran Sasso: • nm CC: 2450 events/kton/yr • nm NC: 823 events/kton/yr • ne’s (0.8%) : 21 events/kton/yr  Similar to MINOS beam (x2 Less nt CC production rate.)

  27. LiqAr LiqAr LiqAr LiqAr Solid Solid Solid Solid Solid ICANOE (ICARUS-NOE) Experiment • Merging of liquid argon calorimeter with magnetized fine grain solid calorimeter • Liq Ar: 4 @ 1250 = 5000 tons • Solid: 4 @ 625 = 2500 tons • Detect and identify all neutrino species

  28. Only 90% CL Limits ICANOE Oscillation Sensitivity • CERN-NGS neutrinos • nt appearance search • Fine grain detector • Kinematical selection • ne appearance search • Good electron ID • Bkgnd from beam ne and nm nt  t  e • Atmospheric neutrinos • Isotropic detector • Good angular and energy resolution for investigating osc. effects • Can reach Solar LMA region for low En and cosqZ= -1

  29. OPERA Hybrid Emulsion Experiment(Oscillation Project with Emulsion-tRacking Apparatus) • Emulsion bricks interspersed with electronics trackers • Trackers determine bricks with neutrino events • Use automated scanning to find and measure events in emulsion • Look for indications of t-decay kink • Goal: 1.5 kton hybrid target • ~ 3,600 nm CC events/yr efficiency • ~ 45 ntevents/yr  efficiency @ Dm2=3.510-3 eV2 • efficiency: ~10 % ?

  30. OPERA Sensitivity • Very low background • Can confirm oscillations with few events • For five year exposure (2.251020 pot) • ~ 20 nm ntosc. events @ Dm2=3.510-3 eV2 • ~ 0.5 events background

  31. LSND Experiment at LANL • Neutrino source from stopped p+s in the proton beam stop. • 1mA, 800 MeV protons • Cerenkov detector: 167 tons @ 30 m • p+ decay chain gives no <En>  40 MeV • Look for (1993-1998)

  32. Distributions of Excess ne Events • Spatial distribution in detector is consistent with ne 12C  e- Ng.s. events • Excess ne events have much higher energy than backgrounds

  33. Restrictions from Other Experiments • CCFR and Nomad rule out high Dm2 region • Bugey Reactor experiment rules out high sin22q and requires Dm2 > 0.2 eV2 • Karmen experiment : - Similar to LSND stopped p+ beam (200 ma) but closer distance (18m) - Sees no indication of oscillation but is not incompatible: • Expected 8 events • Observed 7.8  0.5 events Nomad Sensitivity Need decisive experiment to check LSND result and measure parameters if oscillations MiniBooNE

  34. MiniBooNE (nme)Experiment at Fermilab • Use protons from the 8 GeV booster Neutrino Beam <En>~ 1 GeV • Detector • 12 m sphere filled with mineral oil and PMTs • Located at 500m from neutrino source. • ~1000 event signal if LSND is verified • Expected significance 15 - 44 s • If signal observed, add second detector at appropriate distance(MiniBooNE  BooNE Exp.) Status: Detector construction going on Beam/Target Station design being completed with bid out Sp, 00  Beam and Detector complete end of 2001 Data Run starts end of 2001

  35. MiniBooNE Construction Status Jan. 12, 2000 • Detector enclosure about 30% complete. Picture shows the concrete for the lower half of the wall being finished

  36. MiniBooNE Rates and Sensitivity • Expected events/yr • 500,000 nm CC quasi-elastic • 1275 ne from m decays • 425 ne from K decays • Decisive investigation of LSND region • LSND  >5s signal in MiniBooNE • Osc. signal has different energy than intrinsic ne • Experimental determinations of all backgrounds.

  37. MiniBooNE: Oscillation Parameter Measurements Two signal examples:

  38. MiniBooNE BooNE MINOS CNGS? K2K SuperK SNO Summary • Much more information in next five years LSND: Atmospheric: Year: 2000 01 02 03 04 05 06 07 Solar: KamLand Borexino

  39. Possible Next Step:Muon Storage Ring n-Factory • Muon storage ring could provide a super intense neutrino beamat wide range of energies. • High intensity, mixed beam allows investigation of all mixings • Flavor composition/energy selectable and well understood: • Highly collimated beam • Very long baseline experiments possible Fermilab to California Fermilab to Cern

  40. More Detailed Muon Storage Ring Design

  41. Advantages of Muon Storage Ring • Both ne and nm species in beam: • Only way to get well understood, high-intensity source of ne’snent or nenm • Map out different flavor oscillations • High intensity allows: • Probe small mixing angles • See ntevents in emulsion detector • Long distances • Start to see earth matter effects for oscillations involving ne’s • Reach solar neutrino region with accelerator beams

  42. Comparison with Conventional n Beam

  43. n-events/GeV for various m-beam energies 50 GeV 35 GeV 20 GeV n - Factory Beam and Detector Parameters • High Rate Beam: • 1020 - 1021 muon decays /yr • n rates higher than conventional beams for Estorage > ~20 GeV • Rate in detector  E3 High storage ring energy ~ 50 GeV • Detector: • Large:  10 kton • Need at least midentification (with beam flavor constraints) • Better to also have e and tidentification

  44. Low Dm2 Sensitivity of n-Beams Event rates/yr in 10kt detector Em = 50 GeV Fermilab to Minnesota (730km) SuperK region Sensitivity to Solar LMA

  45. ntAppearance Rates in a n-Factory Beam ntAppearance Rates Em = 50 GeV Fermilab to Minnesota (730km) SuperK region • 1kton emulsion detector at 730km for 1 yr. (Perfect efficiency) • Assuming nm  nt oscillations with sin22q = 1.0

  46. Neutrino Factory Status and Plans • US collaboration working on muon collider R&D for last three years Many ideas and studies applicable to muon storage ring • “Strawman” conceptual designs being done at Fermilab, BNL, CERN • Define physics reach and opportunities • Identify critical R&D needs • Provide a crude cost estimate  Is this a possible project for the next decade? • NSF Physics Division interested in supporting project jointly with DOE • Muon storage ring could be a first step towards a 5-10 TeV collider

  47. Conclusions • Over next 5-10 years will check present hints of neutrino oscillations • If oscillations are confirmed, muon storage ring could provide the means to fill in the neutrino mixing matrix.

  48. Where Do We Stand? Scorecard Are all the positive signals really n oscillations?

  49. Double Kink Event Found: Ds+ t+  m+ Chorus nm ntExperiment • ntappearance experiment: • 800 kg emulsion target to observe t-decay. • Mean decay length ~1.5 mm • Distance/Energy: • 620 m / 26 GeV Dm2 42 eV2 • Rate: • 840,000 nmevents ~ 24,000 effective events for nm nt search • Checks • Found charm-decay events • Ds t event

  50. NOMAD nm ntExperiment • ntappearance experiment in same beam as Chorus: • Drift chambers are target and detector • 2.7 tons (r 0.1 g/cm3) • TRD’s for electron ID • Indirect t-identification through kinematic cuts on t- decay products • Missing transverse energy from outgoing nt in t-decay • Blind analysis using Monte Carlo simulations of signal and background • Many checks on agreement of data and Monte Carlo Likelihood analysis to separate t events from background

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