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Looking for New Physics in Neutrino Experiments

Looking for New Physics in Neutrino Experiments. Morgan Wascko Imperial College London. The Open Questions of Neutrino Physics. What else can neutrinos reveal beyond the Standard Model? How does the mixing really work? What is the nature of neutrino mass?

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Looking for New Physics in Neutrino Experiments

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  1. Looking for New Physics in Neutrino Experiments Morgan Wascko Imperial College London

  2. The Open Questions of Neutrino Physics • What else can neutrinos reveal beyond the Standard Model? • How does the mixing really work? • What is the nature of neutrino mass? • What do neutrinos tell us about cosmology? (I won’t actually cover this today.) Morgan Wascko, Aspen 2007

  3. Comment on the open questions • The open questions I listed are all motivated by experimental results • You might say that some results are more compelling than others, but they’re all worth pursuing • Answering these questions will at least give us a more precise picture of neutrino masses and mixings • This is so far the only observation of physics beyond the Standard Model • If nature is kind, the next generation of neutrino experiments will tear the roof off of the Standard Model! Morgan Wascko, Aspen 2007

  4. Comment on the open questions • The open questions I listed are all motivated by experimental results • You might say that some results are more compelling than others, but they’re all worth pursuing • Answering these questions will at least give us a more precise picture of neutrino masses and mixings • This is so far the only observation of physics beyond the Standard Model • If nature is kind, the next generation of neutrino experiments will tear the roof off of the Standard Model! Morgan Wascko, Aspen 2007

  5. The Open Questions of Neutrino Physics • What else can neutrinos reveal beyond the Standard Model? • How many generations? • How does the mixing really work? • What is the nature of neutrino mass? Morgan Wascko, Aspen 2007

  6. Nu Oscillation HOWTO • Neutrinos oscillate their flavour with distance travelled (time) • Ideally, one measures neutrino flux at birth in a near detector • Then measure flux after ’s have time to oscillate • Can measure appearance and disappearance MINOS near detector data Morgan Wascko, Aspen 2007

  7. Nu Oscillation HOWTO • Neutrinos oscillate their flavour with distance travelled (time) • Ideally, one measures neutrino flux at birth in a near detector • Then measure flux after ’s have time to oscillate • Can measure appearance and disappearance MINOS far detector data Morgan Wascko, Aspen 2007

  8. Neutrino Oscillations Current Situation • Three oscillation signals • Allowed regions indicated • Note: The true answers are actually single points! • Only mass differences, not absolute scale • For 3 neutrinos, should find: Dm212 + Dm223 = Dm213 Reactor Limit LSND nmne Sorel Morgan Wascko, Aspen 2007

  9. Open Question 1 LSND Signal & MiniBooNE • LSND observed 3.8 excess •   e • Taken with atmospheric and solar oscillations, the oscillation hypothesis implies additional neutrino flavours • Sterile! • MiniBooNE is sensitive to the same parameter space • See J. Monroe’s MiniBooNE talk in today’s evening session Morgan Wascko, Aspen 2007

  10. Post MiniBooNE • If MiniBooNE sees a signal, build BooNE • Second detector • Precise measurement • Near term: ICARUS • LAr detector in Gran Sasso • Great /e PID • Longer Term: • OscSNS at Oak Ridge • T2K 2km detector • Future currently uncertain • NOvA near detector Morgan Wascko, Aspen 2007

  11. Post MiniBooNE • If MiniBooNE sees a signal, build BooNE • Second detector • Precise Measurement • Near term: ICARUS • LAr detector in Gran Sasso • Great /e PID • Longer Term: • OscSNS at Oak Ridge • T2K 2km detector • Future currently uncertain • NOvA near detector Morgan Wascko, Aspen 2007

  12. Sterile Neutrinos: Solar Hints • MSW model predicts upturn in spectrum at low energy • SNO and Super-K data do not show it! • Sterile neutrino mixing models give best global fits to data • Reducing threshold should resolve the question • SNO is doing just that with LETA Smirnov Morgan Wascko, Aspen 2007

  13. The Open Questions of Neutrino Physics • What else can neutrinos reveal beyond the Standard Model? • How many generations? (MiniBooNE) • How does the mixing really work? • Is 23 maximal? • What is the value of 13? • Mass hierarchy? • Do leptons violate CP? • What is the nature of neutrino mass? Accelerator neutrino beams And reactor neutrinos Morgan Wascko, Aspen 2007

  14. Neutrino Flavour Mixing Flavour Mass ATMOSPHERIC SK, K2K, MINOS 23 =~45 m223 = ~2.5E-3 eV2 CROSS MIXING CHOOZ, Bugey 13 <~12  is unknown SOLAR SNO, others, KamLAND 12 =~32 m212 = ~8E-5 eV2 Morgan Wascko, Aspen 2007

  15. Neutrino mixing matrix values are large! 0.70.7<0.12 0.5-0.50.7 -0.50.5 0.7 Neutrino Flavour Mixing Flavour Mass ATMOSPHERIC SK, K2K, MINOS 23 =~45 m223 = ~2.5E-3 eV2 SOLAR SNO, others, KamLAND 12 =~32 m212 = ~8E-5 eV2 But so are the uncertainties… Morgan Wascko, Aspen 2007

  16. Improving Precision for Oscillations: Off-Axis Beams • Use kinematics of pion decay to tune the neutrino energy • Flux peak at target energy for desired value of L/E • L is often constrained by geographic considerations… Morgan Wascko, Aspen 2007

  17. T2K:Tokai-to-Kamioka • Start with world’s largest detector: Super-Kamiokande • Super-K III (50kt) is running now • Build new neutrino beam • J-PARC facility in Tokai • Off-axis beam to Super-K • L = 295 km • E = 0.7 GeV • Near detector at 280m to constrain beam flux • Beam should be running in April 2009 • Expect 5E21 POT in 5 years Nishikawa Morgan Wascko, Aspen 2007

  18. T2K:Tokai-to-Kamioka • Start with world’s largest detector: Super-Kamiokande • Super-K III is running now • Build new neutrino beam • J-PARC facility in Tokai • Off-axis beam to Super-K • L = 295 km • E = 0.7 GeV • Near detector at 280m to constrain beam flux • Beam should be running in April 2009 • Expect 5E21 POT in 5 years Morgan Wascko, Aspen 2007

  19. T2K:Tokai-to-Kamioka • Start with world’s largest detector: Super-Kamiokande • Super-K III is running now • Build new neutrino beam • J-PARC facility in Tokai • Off-axis beam to Super-K • L = 295 km • E = 0.7 GeV • Near detector at 280m to constrain beam flux • Beam should be running in April 2009 • Expect 5E21 POT in 5 years Morgan Wascko, Aspen 2007

  20. NOA:(NuMI Off-axis e Appearance) • Start with world’s (current) most powerful  beam • NuMI facility at Fermilab • Build new detectors in off-axis locations • FNAL & Ash River, MN (810 km) • 25 kton far detector • Program of beam upgrades • Goal: 6E21POT • 50% , 50%  • NOvA turn-on as early as 2011 —NUMI-On-axis beam —14mrad off-axis beam (no oscillation) Mualem Morgan Wascko, Aspen 2007

  21. NOA:(NuMI Off-axis e Appearance) • Start with world’s (current) most powerful  beam • NuMI facility at Fermilab • Build new detectors in off-axis locations • FNAL & Ash River, MN (810 km) • 25 kton far detector • Program of beam upgrades • Goal: 6E21POT • 50% , 50%  • NOvA turn-on as early as 2011 Morgan Wascko, Aspen 2007

  22. NovA Open Question 3 Is 23 Maximal? •  disappearance • T2K and NOvA have same goal for 23 •  (sin2223) ~ 0.01 • Problem: Background estimate uncertainties due to neutrino cross section are large • Example: T2K uncertainties in atmospheric parameters • stat. Only • d(nQE/QE)= 5% • d(nQE/QE)=20% • Need better data for physics input! Mualem d(sin2 2q) d(Dm2) Hiraide Morgan Wascko, Aspen 2007

  23. n n (35%) Events K. Hiraide MINERvA design MINERvA detector protoyping Reducing Cross Section Uncertainties • Two FNAL experiments embarking on campaigns to bring  uncertainties down to needed levels • Both experiments will have high statistics data sets with fine-grained detectors • SciBooNE (E-954) • Near detector in Booster beam • Energy perfect for T2K • Antineutrino data! • Will be running this spring (07) • MINERA (E-938) • Near detector in NuMI beam • Wide range of energies • Different nuclear targets • Data in 2009 SciBooNE detector assembly Morgan Wascko, Aspen 2007

  24. Open Question 2 Measuring 13: Current Situation • Reminder: 13 is how CP violation enters the mixing matrices • We hope it’s large enough! • To measure 13, must observe e appearance • Want sensitivities to sin2213>0.01 • Most troublesome BG: mis-identified NC0 • SciBooNE and MINERvA data will solve that! • Accelerator experiments have ambiguities in measuring 13 Reactor Limit LSND nmne Sorel Morgan Wascko, Aspen 2007

  25. Measuring 13: Accelerators T2K Simulated e Appearance Signal • Reminder: 13 is how CP violation enters the mixing matrices • We hope it’s large enough! • To measure 13, must observe e appearance • Want sensitivities to sin2213>0.01 • Most troublesome BG: mis-identified NC0 • SciBooNE and MINERvA data will solve that! • Accelerator experiments have ambiguities in measuring 13 events/22.5kt/5yrs Mine Enrec Dm2=2.5x10-3eV2,sin22q13=0.1 Morgan Wascko, Aspen 2007

  26. Measuring 13: Accelerators T2K Simulated e Appearance Sensitivity • Reminder: 13 is how CP violation enters the mixing matrices • We hope it’s large enough! • To measure 13, must observe e appearance • Want sensitivities to sin2213>0.01 • Most troublesome BG: mis-identified NC0 • SciBooNE and MINERvA data will solve that! • Accelerator experiments have ambiguities in measuring 13 • Statistics only • d(BG) = 10% • d(BG) = 20% Mine Morgan Wascko, Aspen 2007

  27. Measuring 13: Accelerators • Reminder: 13 is how CP violation enters the mixing matrices • We hope it’s large enough! • To measure 13, must observe e appearance • Want sensitivities to sin2213>0.01 • Most troublesome BG: mis-identified NC0 • SciBooNE and MINERvA data will solve that! • Accelerator experiments have ambiguities in measuring 13 • Tied to atmospheric parameters • CP violation? Morgan Wascko, Aspen 2007

  28. Far Detector Reactor Near Detector ne? ne 2 Measuring 13: Reactors • Use near/far detectors to search for e disappearance • Use inverse  decay • Well know cross section • Great BG rejection 13 Morgan Wascko, Aspen 2007

  29. Measuring 13: Reactors Double CHOOZ (France) • Double CHOOZ • Build two detectors at CHOOZ site • First data in 2008 • Daya Bay • Two detectors at Daya Bay reactor site in China • First data in 2011 • Unambiguous sensitivity to sin2213 • DC: ~0.03 • DB: ~0.01 Daya Bay (China) Morgan Wascko, Aspen 2007

  30. Measuring 13: Reactors Double CHOOZ • Double CHOOZ • Build two detectors at CHOOZ site • First data in 2008 • Daya Bay • Two detectors at Daya Bay reactor site in China • First data in 2011 • Unambiguous sensitivity to sin2213 • DC: ~0.03 • DB: ~0.01 Tonazzo Daya Bay Wang Morgan Wascko, Aspen 2007

  31. e W e Open Question 2 Mass Hierarchy • Is m3>m2? • m2atm ~10-3 • m2sol ~10-5 • e and e scatter with different rates in matter • Raises effective mass of e • Lowers effective mass of e • Changes oscillation probabilities! • P(e) P (e) Diagram taken from Boris Kayser Morgan Wascko, Aspen 2007

  32. Mass Hierarchy • Matter effects change oscillation probabilities! • P(e) P (e) • If neutrinos oscillate more, it’s a normal hierarchy • If antineutrinos oscillate more, it’s an inverted hierarchy • Effect grows with energy • Two experiments at fixed L/E • R>1  Normal • R<1  Inverted • NOvA, with higher L and E, will see a much larger effect than T2K Where S = Sign(m223) Morgan Wascko, Aspen 2007

  33. Open Question 2 CP Violation via Oscillation Measurements • The Holy Grail of oscillations • Further ambiguities: • P(e) P (e) is also the signature for CP violation • Because of the need to know 13, and disentangle matter effects, observing CP violation requires a broad program of experiments • Want a reactor to measure 13 • Want an accelerator that will see matter effects • Want an accelerator that will NOT see matter effects • Need a lot of statistics in both neutrino and antineutrinos! Morgan Wascko, Aspen 2007

  34. The Open Questions of Neutrino Physics • What else can neutrinos reveal beyond the Standard Model? • How many generations? MiniBooNE • How does the mixing really work? • Is 23 maximal? • What is the value of 13? • Mass hierarchy? • Do leptons violate CP? • What is the nature of neutrinos? • What is the absolute scale? • Majorana or Dirac? • Are neutrino interactions different? Accelerator neutrino beams And reactor neutrinos Morgan Wascko, Aspen 2007

  35. Open Question 3 Absolute Mass Scale • Why so light? • Can use kinematics to determine the mass of neutrinos directly • e: m < ~2 eV ( decay) • : m < 0.19 MeV ( decay) • : m < 18.2 MeV ( decay (hadronic)) • Best limits come from tritium decay • 2 main experimental techniques • Spectrometers • Measure energy of emitted electron • Calorimeters • Measure heat increase due to emitted electron Morgan Wascko, Aspen 2007

  36. Tritium Decay Experiments Bornschein 3H3He  e • Measure tritium decay spectrum • Look at endpoint for evidence of neutrino mass • Detector resolution sets mass sensitivity Elliot Morgan Wascko, Aspen 2007

  37. Electron analyzer Electron counter Source T2 Troitsk Detector Mainz Detector Tritium Decay: Spectrometers • Best existing limits come from spectrometer experiments • “MAC-E filter” • Magnetic Adiabatic Collimation with Electrostatic Filter • Integrating high pass filter • Troitsk • m2(n) = -2.3 ± 2.5 ± 2.0 eV2 m(n)< 2.2 eV (95% C.L.) • Mainz • m2(n) = -0.6 ± 2.2 ± 2.1 eV2 m(n)< 2.3 eV (95% C.L.) Morgan Wascko, Aspen 2007

  38. Next Generation Tritium Decay: KATRIN • Combine best of Mainz and Troitsk techniques • Much larger experiment! • Aim: improve mass reach by one order of magnitude • sensitivity • m(n) < 0.2 eV (90% CL) • discovery potential • m(n) = 0.35 eV (5s) • Will observe Heidelberg-Moscow size mass neutrino if it exists! • Installation in progress… 70 m Morgan Wascko, Aspen 2007

  39. Morgan Wascko, Aspen 2007

  40. P e-2 P e-1 Left  C n n Left Open Question 3 Majorana Mass? • Use rare nuclear transitions that emit 2 s • “Line” detected at the endpoint energy indicates neutrinoless double  • Can only happen if neutrinos are Majorana particles • 2 primary experimental approaches: • Source = Detector (SED) • Tracker-Calorimeters (TC) • Search for decays; limits on half-life for decays yield limits on neutrino mass Gomez Cadenas Thomas Morgan Wascko, Aspen 2007

  41. Experimental Techniques 1: SED • Examples: • Ge detectors • Bolometers • Excellent energy resolution, efficiency • No pattern in signal, just energy deposit • Limited to single isotope per experiment • Dominant BG: External radioactivity • Current limits: • CUORICINO: • mn < (0.18-0.94) eV Cuoricino detector block Cuoricino data Bellini Morgan Wascko, Aspen 2007

  42. B(25 G) Side view Top view Experimental Techniques 2: TC Source foils + tracker+ calorimeter • Example: NEMO-3 • “Pattern” signature observed • Multiple sources in same detector • Modest energy resolution • Resolution of calorimeter • Energy loss in foils • Dominant BG: internal double  decays • 82Se: mn < 1.3 – 3.6 eV • 100Mo: mn < 0.7 – 1.2 eV • Expected Reach in 5 years after RadonPurification • 100Mo: mn < 0.2 – 0.35 eV • 82Se: mn < 0.65 – 1.8 eV 3 m 4 m Morgan Wascko, Aspen 2007

  43. 0: Possible Signal? • Heidelberg-Moscow experiment (Ge) has published a signal claim • Enriched 76Ge detector • Total mass 10.9 kg • m = 0.39 eV (95% CL) • Controversial • Needs confirmation! Morgan Wascko, Aspen 2007

  44. 0: Next Generation • Many next generation experiment proposals • 4 that are most on mass shell: • CUORE • EXO • MAJORANA • Super NEMO • Broad program using different isotopes • Will reach sensitivities sufficient to confirm or refute the Heidelberg-Moscow result Thomas Bellini Morgan Wascko, Aspen 2007

  45. Open Question 3 The NuTev Result • Measurement of sin2W differs by 3 from SM! • Find: sin2W=0.2277 0.00130.0009 • cf. sin2W=0.22270.0003 • Precise measurement uses Paschos-Wolfenstein relation • Clean  and  beams • SSQT • Recall LEP result favors N = 2.9841  0.0083 Morgan Wascko, Aspen 2007

  46. e e W Z e e Open Question 1 Addressing NuTeV • Reactor  elastic scattering can be used to measure weak angle • Total event rate is sensitive to sin2W • Normalize rate using inverse  decay • Cross section known to 0.2% • Address the mixing angle with neutrinos at low Q2 • Main BGs come from other  decays and neutron spallation Conrad Morgan Wascko, Aspen 2007

  47. e e W Z e e Addressing NuTeV • Reactor  elastic scattering can be used to measure weak angle • Total event rate is sensitive to sin2W • Normalize rate using inverse  decay • Cross section known to 0.2% • Address the mixing angle with neutrinos at low Q2 • Main BGs come from other  decays and neutron spallation Morgan Wascko, Aspen 2007

  48. Best Bets For New Physics “Soon”(N.B.: I bet on the USA to win the World Cup) • MiniBooNE • Could reveal new generations • Neutrinoless Double  Decay • Majorana neutrinos? • Absolute mass scale • Maybe not “NEW PHYSICS”, but it would set the scale for neutrino masses Morgan Wascko, Aspen 2007

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