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Aspen 2002

Aspen 2002. Recent Results from Super-K (and K2K) Neutrino Oscillations Jordan Goodman University of Maryland. & Mechanical Chain Reactions. Super-Kamiokande. Detecting neutrinos. Cherenkov ring on the wall. Electron or muon track. The pattern tells us the energy and type of particle

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Aspen 2002

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  1. Aspen 2002 Recent Results from Super-K (and K2K) Neutrino Oscillations Jordan Goodman University of Maryland & Mechanical Chain Reactions

  2. Super-Kamiokande

  3. Detecting neutrinos Cherenkov ring on the wall Electron or muon track The pattern tells us the energy and type of particle We can easily tell muons from electrons

  4. A muon going through the detector

  5. A muon going through the detector

  6. A muon going through the detector

  7. A muon going through the detector

  8. A muon going through the detector

  9. A muon going through the detector

  10. Stopping Muon

  11. Stopping Muon – Decay Electron

  12. Neutrino Production Ratio predicted to ~ 5% Absolute Flux Predicted to ~20% :

  13. about 15 km about 13,000 km Atmospheric Oscillations We look for n transformations by looking at ns with different distances from production SK Neutrinos produced in the atmosphere

  14. n - e e + W n p Atmospheric Neutrino Interactions Reaction Thresholds Electron: ~1.5 MeV Muon: ~110 MeV Tau: ~3500 MeV Neutral Current Charged Current

  15. Telling particles apart Muon Electron

  16. Muon - Electron Identification PID Likelihood sub-GeV, Multi-GeV, 1-ring Monte Carlo (no oscillations) We expect about twiceas many nm as ne

  17. Super-K Atmospheric Data Set • 1289.4 days of data (22.5 kilotons fiducial volume) • Data Set is divided into: • Single and Multi Ring events • Electron-like and Muon-like • Energy Intervals • 1.4 GeV< Evis >1.4 GeV • Also Evis< 400MeV (little or no pointing) • Fully or partially contained muons (PC) • Upward going muons - stopping or through going • Data is compared to Atmospheric Monte Carlo • Angle (path length through earth) • Visible energy of the Lepton

  18. Low Energy Sample No Oscillations Oscillations (1.0, 2.4x10-3eV2)

  19. Moderate Energy Sample

  20. Multi-GeV Sample No Oscillations Oscillations (1.0, 2.4x10-3eV2) Down UP Down UP going

  21. Multi-Ring Events

  22. Upward Going Muons

  23. Summary of Atmospheric Results Compelling evidence for nm to nt atmospheric neutrino oscillations Best Fit for nmto nt Sin22q =1.0, DM2=2.4 x 10-3eV2 c2min=132.4/137 d.o.f. No Oscillations c2min=316/135 d.o.f. 99% C.L. 90% C.L. 68% C.L. Best Fit Now the most cited exp. HEP paper

  24. Tau vs Sterile Neutrino Analysis

  25. Tau’s require greater than 3 GeV in neutrino energy This eliminates most events Three correlated methods were used All look for enhanced upward going multi-ring events All show slight evidence for Tau appearance None are statistically significant Tau Appearance?

  26. The p0 sample • For nmto ns the rate of NC events is reduced as compared to nmto nt • The SK NC enriched sample is only about 1/3 from NC interactions. • The p0 sample is the cleanest NC signal • Until now the error in s(p0)(~1-2 Gev) has been as large as the effect!

  27. Original SK Systematic Errors • Systematic Error in rp0=(p0/Q.E.) • Cross section – 20% • Reconstruction – 7% • Nuclear Interaction – 7% • Flux – 3% • Total Systematic – 23%

  28. Original Results from p0s

  29. K2K Near Detector K2K beam is: ~1.3 GeV 98.2% nm 1.3% ne 0.5% nm

  30. p0Peaks

  31. Monte Carlo of p0 Production

  32. Use K2K to measure the Cross Section • A normalized p0 rate is defined as rp0=(p0/mfc) • Form double ratio of Rp0= rp0(data)/rp0(MC) to minimize flux uncertainties and nuclear effects • Simulate both K2K and SK flux and efficiencies • K2K finds Rp0 = 1.04 ± 0.02 ± 0.02 ± 0.09 Stat (data MC) Sys • Old SK Rp0 = 1.05 ± 0.05 ± 0.01 ± 0.23 • Both are consistent with Rp0 = 1 • Use K2K measurement to improve SK result

  33. New Systematic Errors in SK • Using K2K Result • Reconstruction – 7% • Flux – 3% • Spectral Diff between SK and K2K – 5% • Cross section/Nuclear effects – 12% (flux averaged) • Total Systematic – 14%

  34. New Results

  35. The Solar Neutrino Problem

  36. n e - e - W n - e e Charged Current n (electron ’s only) Solar Neutrinos in Super-K • The ratio of NC/CC cross section is ~1/6.5

  37. Solar Neutrinos in Super-K • Super-K measures: • The flux of 8B solar neutrinos (electron type) • Energy, Angles, Day / Night rates, Seasonal variations • Super-K Results: • We see the image of the sun from 1.6 km underground • We observe a lower than predicted flux of solar neutrinos (45%) Skip Solar

  38. Solar Neutrinos Toward Sun From Sun

  39. Energy Spectrum

  40. Day / Night - BP2000+New 8B SpectrumPreliminary

  41. Seasonal/Sunspot Variation

  42. 95% excluded by SK flux-independent zenith angle energy spectrum 95% C.L allowed. - SK flux constrained w/ zenith angle energy spectrum Enlarged View Combined Results netonm,t SK + Gallium + Chlorine - flux only allowed 95% C.L.

  43. Combined Results netonsterile SK + Gallium+ Chlorine - flux only allowed 95% C.L. 95% excluded by SK flux-independent zenith angle energy spectrum 95% C.L allowed. - SK flux constrained w/ zenith angle energy spectrum

  44. SNO measures just ne SK measures mostly ne but also other flavors (~1/6 strength) From the difference we see oscillations! This is from nm & nt neutral current } SNO Results - Summer 2001

  45. Combining SK and SNO • SNO measures just electron neutrinos and gets Fne= (35% ± 3%)Fssm • This implies that Fnm,t= ~65% Fssm (~2/3 have oscillated) • SK measures Fes =(Fne + (Fnm,t)/6.5) • Assuming osc. SNO predicts that SK will see Fes ~ (35%+ 65%/6.5) Fssm = 45% ± 3% Fssm • SK observes:

  46. Md Students at Super-K

  47. Super-K Disaster - Nov 12, 2001 • Chain reaction destroyed 7000 OD and 1000 ID Tubes • The cause is not completely understood, but it started with a lower pmt collapse. • There are plans to rebuild… • ½ density detector within 1 year • Eventually rebuild completely

  48. Disaster (Continued)

  49. Disaster (Continued)

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