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Neutrino Experiments

Neutrino Experiments. Kevin McFarland University of Rochester Weak Interactions and Neutrinos Delfoi , 6 June 2005. Neutrinos: View from the Center of the Earth. Today we’ll choose a broad overview rather than a focused study in depth

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Neutrino Experiments

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  1. Neutrino Experiments Kevin McFarlandUniversity of Rochester Weak Interactions and NeutrinosDelfoi, 6 June 2005

  2. Neutrinos: View from theCenter of the Earth • Today we’ll choose a broad overview • rather than a focused study in depth • neutrino people: this is for the energy frontier folks.please be patient! you’ll get your turn later in the week Kevin McFarland, Neutrinos (Expt'l) clever photos courtesy Symmetry magazine

  3. n n The Broadest Goals • Understand mixing of neutrinos • a non-mixing? CP violation? • Understand neutrino mass • absolute scale and hierarchy • Understand n interactions • new physics? new properties? • Use neutrinos as probes • nucleon, earth,sun*, supernovae* * fascinating topics, but outside the scope of this talk. See Dave Wark… Kevin McFarland, Neutrinos (Expt'l)

  4. Neutrino Mass Eigenstates • The building blocks of what we know • #ns with weak couplings: • W+: 3 observed (DONUT) • Z0: exactly 3 (LEP, SLD) • Solar neutrino oscillation: …, SNO, KAMLAND • Atmospheric neutrinos: …, Super-K, K2K • Puzzles and null results: LSND, CHOOZ • LSND “puzzle” is requirement of more neutrinos • CHOOZ/Palo Verde suggest one small mixing Kevin McFarland, Neutrinos (Expt'l)

  5. Qualitative Questions • The questions facing us now are fundamental, and not simply a matter of “measuring oscillations better” • Examples: • Are there more than three neutrinos? • What is the hierarchy of masses? • Can neutrinos contribute significantly to the mass of the universe? • Is there CP violation in neutrino mixings? Kevin McFarland, Neutrinos (Expt'l)

  6. n n The Broadest Goals • Understand mixing of neutrinos • a non-mixing? CP violation? • Understand neutrino mass • absolute scale and hierarchy • Understand n interactions • new physics? new properties? • Use neutrinos as probes • nucleon, earth, etc. Kevin McFarland, Neutrinos (Expt'l)

  7. What We Hope to Learn From Neutrino Oscillations • Near future • validation of three generation picture • confirm or disprove LSND oscillations • precision tests of “atmospheric” mixing at accelerators • Farther Future • neutrino mass hierarchy, CP violation? • Precision at reactors • sub  multi MegaWatt sources • 10  100  1000 kTon detectors Kevin McFarland, Neutrinos (Expt'l)

  8. Minimal Oscillation Formalism • If neutrino mass eigenstates: n1, n2, n3, etc. • … are not flavor eigenstates: ne, nm, nt • … then one has, e.g., take only two generations for now! different masses alter time evolution time Kevin McFarland, Neutrinos (Expt'l)

  9. e- density Oscillation Formalism (cont’d) • So, still for two generations… • Oscillations require mass differences • Oscillation parameters are mass-squared differences, dm2, and mixing angles, q. • One correction to this is matter… changes q, L dep. appropriate units give the usual numerical factor1.27 GeV/km-eV2 Wolfenstein, PRD (1978) Kevin McFarland, Neutrinos (Expt'l)

  10. SAGE - The Russian-AmericanGallium Experiment Solar Neutrinos • There is a glorious historyof solar neutrino physics • original goals: demonstratefusion in the sun • first evidence of oscillations Kevin McFarland, Neutrinos (Expt'l)

  11. Culmination: SNO • D2O target uniquely observes: • charged-current • neutral-current • The former is onlyobserved for ne(lepton mass) • The latter for all types • Solar flux is consistentwith models • but not all ne at earth Kevin McFarland, Neutrinos (Expt'l)

  12. KAMLAND • Sources areJapanesereactors • 150-200 kmfor most offlux. Rate uncertainty ~6% • 1 kTon scint. detector inold Kamiokande cavern • overwhelming confirmationthat neutrinos change flavorin the sun via mattereffects Kevin McFarland, Neutrinos (Expt'l)

  13. Solar Observations vs. KAMLAND • Solar neutrino observations are best measurement of the mixing angle • KAMLAND does better on dm212 + KAMLAND = Kevin McFarland, Neutrinos (Expt'l)

  14. Atmospheric Neutrinos • Neutrino energy: few 100 MeV – few GeV • Flavor ratio robustly predicted • Distance in flight: ~20km (down) to 12700 km (up) Kevin McFarland, Neutrinos (Expt'l)

  15. Super-Kamiokande • Super-Kdetector hasexcellent e/mseparation • Up / down difference! 2004 Super-K analysis old, but good data! Kevin McFarland, Neutrinos (Expt'l)

  16. Neutrino Beam from KEK to Super-K K2K figures courtesy T. Nakaya • Experiment has completeddata-taking • confirms atmosphericneutrino oscillation parameters with controlled beam • constraint on dm223 (limited statistics) Kevin McFarland, Neutrinos (Expt'l)

  17. Enough For Three Generations figures courtesy B. Kayser • Oscillations have told us the splittings in m2, but nothing about the hierarchy • The electron neutrino potential (matter effects) can resolve this in oscillations, however. dmsol2 dm122≈8x10-5eV2dmatm2 dm232≈2.5x10-3eV2 Kevin McFarland, Neutrinos (Expt'l)

  18. Three Generation Mixing slide courtesy D. Harris • Note the new mixing in middle, and the phase, d Kevin McFarland, Neutrinos (Expt'l)

  19. But CHOOZ… • Like KAMLAND, CHOOZ and Palo Verde expt’s looked at anti-ne from areactor • compare expected to observed rate, s~4% • If electron neutrinos don’t disappear, they don’t transform to muon neutrinos • limits nm->ne flavor transitions at and therefore |Ue3| is “small” dm223 Kevin McFarland, Neutrinos (Expt'l)

  20. Optimism has been Rewarded • By which he meant…had not Eatm n/Rearth < dmatm2 <Eatm n/hatmand had not solar density profileand dmsol2 beenwell-matched… • We might not be discussingn oscillations! “We live in the best of all possible worlds” – Alvaro deRujula, Neutrino 2000 Kevin McFarland, Neutrinos (Expt'l)

  21. Are Two Paths Open to Us? • If “CHOOZ” mixing, q13, is small, but not too small, there is an interesting possibility • At atmospheric L/E, dm232, q13 ne nm dm122, q12 LARGE SMALL LARGE SMALL Kevin McFarland, Neutrinos (Expt'l)

  22. Implication of two paths • Two amplitudes • If both small,but not too small,both can contribute ~ equally • Relative phase, d, between them can lead toCP violation (neutrinos and anti-neutrinos differ) in oscillations! dm232, q13 ne nm dm122, q12 Kevin McFarland, Neutrinos (Expt'l)

  23. Leptons Have Rediscovered the Wonders of Three Generations! • CP violation and matter effects lead to a complicated mix… • CP violation gives ellipsebut matter effects shiftthe ellipse in along-baseline acceleratorexperiment… Minakata & Nunokawa JHEP 2001 Kevin McFarland, Neutrinos (Expt'l)

  24. But LSND… figures courtesy S. Brice • LSND anti-ne excess • 87.9±22.4±6.0 events • statistically overwhelming;however… LSND dm2 ~ 0.1-1.0 eV2 Atmos. dm2 ≈ 2.5x10-3 eV2 Solar dm2 ≈ 8.0x10-5 eV2 cannot be accommodated with only three neutrinos Kevin McFarland, Neutrinos (Expt'l)

  25. SignalMis-IDBeam MiniBooNE figures courtesy S. Brice • A very challenging experiment! • Have ~0.5E21protons on tape • First neappearanceresults inlate 2005 Kevin McFarland, Neutrinos (Expt'l)

  26. Next Steps(Brazenly Assuming Three Neutrinos) • MINOS and CNGS • Reactors • T2K and NOvA • Mating Megatons and Superbeams • Beta (ne) beams andneutrino factories (mne and nm) graphical witcourtesy A. deRujula Kevin McFarland, Neutrinos (Expt'l)

  27. Isn’t all of this overkill? • Disentangling the physics from the measurements is complicated (S. Parke) • The short version of the story is that different measurements have different sensitivity to matter effects, CP violation • Matter effects amplified for long L, large En • CP violation cannot be seen in disappearance (reactor) measurement nene Kevin McFarland, Neutrinos (Expt'l)

  28. NuMI-Based Long Baseline Experiments • 0.25 MWatt  0.4 MWatt proton source • Two generations: • MINOS (running) • NOvA (future)15mrad Off Axis Kevin McFarland, Neutrinos (Expt'l)

  29. MINOS Goal: precise nmdisappearance measurement Gives dm223 735km baseline 5.4kton Far Det. 1 kton Near Det. Running since early 2005 Kevin McFarland, Neutrinos (Expt'l)

  30. t n 1 mm Pb Emulsion layers 1.8kTon fiugres courtesy A. Bueno figures courtesy D. Autiero CNGS • Goal: ntappearance • 0.15 MWatt source • high energy nmbeam • 732 km baseline • handfuls of events/yr e-, 9.5 GeV, pT=0.47 GeV/c  interaction, E=19 GeV 3kton Kevin McFarland, Neutrinos (Expt'l)

  31. Back to Reactors • Recall thatKAMLANDsaw anti-nedisappearanceat solar L/E • Have not seendisappearance atatmospheric L/E Kevin McFarland, Neutrinos (Expt'l)

  32. Why Reactors? • CHOOZ (reactor) has left us without evidence of anti-ne disappearance indicating |Ue3|>0 • reactors are still the most sensitive probe! • CHOOZ used a single detector • therefore, dead-reckoning used to estimate neutrino flux from the reactor • could improve with a near/far technique • KAMLAND has improved knowledge of how to reject backgrounds significantly(remember, their reactors are ~200 km away!) Kevin McFarland, Neutrinos (Expt'l)

  33. not an engineering drawing How Reactors? • To get from ~4% uncertainties to ~1% uncertainties, need a near detector to monitor neutrino flux • For example, Double-CHOOZ proposes to add a secondnear detector and compare rates • new detectors with 10 ton mass • total error budget on rate ~2% • low statistics 10t limit spectraldistortion, 1 km baseline likelyshorter than optimum • Optimization beyond Double-CHOOZ… • ~100 ton detector mass • optimize baseline for dm223 • background reduction with active or passive shielding Kevin McFarland, Neutrinos (Expt'l)

  34. Where Reactors? • A series of proposals with different technical choices • All challenging experiments to limit systematics Kevin McFarland, Neutrinos (Expt'l)

  35. Megawatt Class Beams • J-PARC • initially 0.7 MWatts  4 MWatts • FNAL Main Injector • current goal 0.25 MWatts  0.4 MWatts • future proton driver upgrades? • Others? Kevin McFarland, Neutrinos (Expt'l)

  36. J-PARC Facility Kevin McFarland, Neutrinos (Expt'l)

  37. A Digression: Off-axis • First Suggested by Brookhaven (BNL 889) • Take advantage of Lorentz Boost and 2-body kinematics • Concentrate nm fluxat one energy • Backgrounds lower: • NC or other feed-downfrom highlow energy • ne (3-body decays) figure courtesy D. Harris Kevin McFarland, Neutrinos (Expt'l)

  38. T2K • Tunable off-axis beam from J-PARC to Super-K detector • beam and nm backgrounds are kept below 1% for ne signal • ~2200 nm events/yr (w/o osc.) d=0, no matter effects Kevin McFarland, Neutrinos (Expt'l) figures courtesy T. Kobayashi

  39. NuMI-Based Long Baseline Experiments • 0.25 MWatt  0.4 MWatt proton source • Two generations: • MINOS (running) • NOvA (future)15mrad Off Axis Kevin McFarland, Neutrinos (Expt'l)

  40. NOnA figure courtesy M. Messier • Use Existing NuMI beamline • Build new 30kTon Scintillator Detector • 820km baseline--compromise between reach in q13 and matter effects Goal: neappearance In nmbeam Assuming Dm2=2.5x10-3eV2 figures courtesy J. Cooper ne+A→p p+p- e- Kevin McFarland, Neutrinos (Expt'l)

  41. Future Steps after T2K, NOvA • Beam upgrades (2x – 5x) • Megaton detectors (10x – 20x) • BUT, it’s hard to make such steps without encountering significantTECHNICAL DIFFICULTIES • hereafter “T.D.” Kevin McFarland, Neutrinos (Expt'l)

  42. TD: More Beam Power, Cap’nExample: Fermilab Proton Driver Neutrino “Super- Beams” SY-120 Fixed-Target NUMI Off- Axis 8 GeV neutrino 8 GeV Linac ~ 700m Active Length Main Injector @2 MW Parallel Physics and Machine Studies … main justification Is to serve as source for new Long baseline neutrino experiments Kevin McFarland, Neutrinos (Expt'l) figure courtesy G.W. Foster

  43. TDs: Beamlines pictures courtesy D. Harris • Handling Many MWatts of proton power and turning it into neutrinos is not trivial! NuMI Horn 2. Note conductors and alignment fixtures NuMI tunnel boring machine. 3.5yr civil construction NuMI Target shielding. More mass than far detector! NuMI downstream absorber. Note elaborate cooling. “Cost more than NuTeV beamline…” – R. Bernstein Kevin McFarland, Neutrinos (Expt'l)

  44. TDs: Detector Volume • Scaling detector volume is notso trivial • At 30kt NOvA is about the same mass as BaBar, CDF, Dzero, CMS and ATLAS combined… • want monolithic, manufacturabile structures • seek scaling as surface rather than volume if possible figure courtesy G. Rameika Kevin McFarland, Neutrinos (Expt'l)

  45. Consider the Temple of the Olympian Zeus… 17m tall, just like NOvA! a bit over ½ the length It took 700 years to complete delayed for lack of funding for a few hundred years Fortunately construction technology has improved has the funding situation? 17m For Perspective… your speaker Kevin McFarland, Neutrinos (Expt'l)

  46. 120m long, 10% less than NOvA roughly the same height and width It was rebuilt over a mere four years Funded byJohn D. Rockfeller Morals: grand endeavors! know who holds your checkbook… 120m Perspective (cont’d)… • Consider theStoa toy Attaloy … your speaker Kevin McFarland, Neutrinos (Expt'l)

  47. 60m 60m Span 40% photocathode 10% photocathode Depth (below surface) UNO. ~1Mton. (20x Super-K) UNO: 60m span1500m depth TDs: Detector Volume (cont’d) • For megatons, housing a detector is difficult! • Sensor R&D: focus on reducing cost • in case of UNO,large photocathode PMTs • goal: automated production,1.5k$/unit figures courtesy C.-K. Jung Field Map, Burle 20” PMT Kevin McFarland, Neutrinos (Expt'l)

  48. n–p0 nn+ TDs: Neutrino Interactions figures courtesy D. Casper, G. Zeller • At 1-few GeV neutrino energy (of interest for osc. expt’s) • Experimental errors on total cross-sections are large • almost no data on A-dependence • Understanding of backgrounds needsdifferential cross-sections on target • Theoretically, this region is a mess…transition from elastic to DIS Kevin McFarland, Neutrinos (Expt'l)

  49. Great experimental benefits to new beam technology, but beams are very challenging! And costly… Conventional Beam Beta Beam Neutrino Factory Futuristic Accelerator Beams figures courtesy D. Harris Detector Needs Kevin McFarland, Neutrinos (Expt'l)

  50. More to learn from the sky? • Sign-separated atmospheric neutrinos • MINOS detector is first with this capability • determine chargefrom bend • Why study neutrino vs. anti-neutrino oscillations? • possibility to test CPT violation scenarios if suggested by MiniBooNE and LSND results Time vs Y Time vs Z y x z Y vs X Strip vs Plane ~1 yr MINOS Y vs Z figures courtesy M. Bishai, H. Gallagher Kevin McFarland, Neutrinos (Expt'l)

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