particle physics seminar

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particle physics seminar

  1. 1. Atmospheric neutrinos <ul><li> from decay of  , K and  produced by interactions of cosmic rays in the atmosphere </li></ul><ul><li>Up-down symmetric except for geomagnetic effects </li></ul><ul><li>Useful beam for neutrino oscillations? </li></ul>From D. Ayres, A.K. Mann et al., PR D84 (1984) 902 & Snowmass, 1982 <ul><li>References: </li></ul><ul><li>TKG & M. Honda, Ann. Revs. </li></ul><ul><li>Nucl. Part. Sci. 52 (2002) </li></ul><ul><li>TKG, Proc. Neutrino 2002 </li></ul>
  2. 2. Historical context <ul><li>Particle physics with cosmic rays: pre-1960 </li></ul><ul><li>Discovery of positron, muon, pion and kaon </li></ul><ul><li>Hadronic scaling (Heitler & Janossy, 1949) --  secondary (E) = Z ps  p (E) </li></ul><ul><li>Study of elementary particles by the photographic method </li></ul><ul><li>Powell, Fowler & Perkins, 1959 </li></ul><ul><li>Stability of matter: search for proton decay, 1980’s </li></ul><ul><li>IMB & Kamioka -- water Cherenkov detectors </li></ul><ul><li>KGF, NUSEX, Frejus, Soudan -- iron tracking calorimeters </li></ul><ul><li>Principal background is interactions of atmospheric neutrinos </li></ul><ul><li>Need to calculate flux of atmospheric neutrinos </li></ul><ul><li>Two methods: </li></ul><ul><li>From muons to parent pions infer neutrinos (Zatsepin & Kuz’min; Perkins) </li></ul><ul><li>From primaries to  , K and  to neutrinos (Cowsik, TKG & Stanev…) </li></ul><ul><li>Giles Barr 1986/87 </li></ul>e    e  p   
  3. 3. Historical context (cont’d) <ul><li>Atmospheric neutrino anomaly - 1986, 1988 … </li></ul><ul><li>IMB too few  decays (from interactions of   ) 1986 </li></ul><ul><li>Kamioka  -like / e-like ratio too small. </li></ul><ul><li>Neutrino oscillations first explicitly suggested in 1988 Kamioka paper </li></ul><ul><li>Discovery of neutrino oscillations </li></ul><ul><li>Super-K: “Evidence for neutrino oscillations” at Neutriino 98 </li></ul><ul><li>Subsequent increasingly detailed analyses from Super-K 1998… </li></ul><ul><li>Confirming evidence from MACRO and Soudan </li></ul><ul><li>SNO results on oscillations of solar neutrinos </li></ul><ul><li>Analyses based on ratios comparing to 1D calculations </li></ul><ul><li>Need for precise, complete, accurate, 3D calculations </li></ul><ul><li> ~ P T / E is large for sub-GeV neutrinos </li></ul><ul><li>Bending of muons in geomagnetic field important for  from  decay </li></ul><ul><li>Complicated angular/energy dependence of primaries (AMS measurement) </li></ul><ul><li>Use improved primary spectrum and hadroproduction information </li></ul>  e    e  p 
  4. 4. Outline of talk <ul><li>Overview of calculations </li></ul><ul><li>E  < 10 GeV (contained) </li></ul><ul><ul><li>Sources of uncertainty </li></ul></ul><ul><ul><ul><li>Primary spectrum </li></ul></ul></ul><ul><ul><ul><li>Hadronic interactions </li></ul></ul></ul><ul><ul><li>Comparison of calculations </li></ul></ul><ul><ul><li>Geomagnetic effects </li></ul></ul><ul><ul><li>3 D calculations </li></ul></ul><ul><li>High energy (     &  e ) </li></ul><ul><ul><li>Importance of kaons </li></ul></ul><ul><ul><li>Calibration of  - telescopes </li></ul></ul><ul><ul><li>Prompt background </li></ul></ul><ul><li>Summary </li></ul>Distribution of E  for 4 classes of events determines how oscillation effects appear P(     ) = 1 - sin 2 2  sin 2 [1.27  m 2 (eV 2 ) L km / E GeV ] for two-flavor mixing in vacuum
  5. 5. Overview of the calculation
  6. 6. Primary spectrum <ul><li>Largest source of overall uncertainty </li></ul><ul><ul><li>1995: experiments differ by 50% (see lines) </li></ul></ul><ul><ul><li>Present: AMS, BESS within 5% for protons </li></ul></ul><ul><ul><li>discrepancy for He larger, but He only 20% of nucleon flux </li></ul></ul><ul><ul><li>overall range (neglect highest and lowest): </li></ul></ul><ul><ul><ul><li>+/-15%, E < 100 GeV </li></ul></ul></ul><ul><ul><ul><li>+/- 30%, E ~ TeV </li></ul></ul></ul>Protons Helium
  7. 7. Comparison (using same event generator) <ul><li>sub-GeV flux increases slightly using new flux from AMS & BESS </li></ul>AMS/BESS Kamioka Soudan/SNO    e    e
  8. 8. Hadronic interactions <ul><li> - yields depend most on treatment of  production </li></ul><ul><li>Compare 3 calculations: </li></ul><ul><ul><li>Bartol (Target) </li></ul></ul><ul><ul><li>Honda et al. (1995: Fritiof; present: Dpmjet3) </li></ul></ul><ul><ul><li>Battistoni et al. (Fluka) </li></ul></ul><ul><li>Uncertainties from interactions ~ +/-15% </li></ul>
  9. 9. Comparison (using same flux) <ul><li>New calculations lower than old, e.g.: </li></ul><ul><ul><li>Target-2.1/ -1 </li></ul></ul><ul><ul><li>Dpmjet3 / HKKM </li></ul></ul><ul><ul><li>3 new calculations agree at Kamioka but not for Soudan/SNO </li></ul></ul><ul><li>Larger uncertainty at high geomagnetic  </li></ul><ul><ul><li>Interactions < 10 GeV are important </li></ul></ul>Kamioka Soudan/SNO    e    e
  10. 10. New hadro-production data <ul><li>Diagram: </li></ul><ul><ul><li>Lego plot shows phase space weighting for sub-GeV events </li></ul></ul><ul><ul><li>Bars show existing data </li></ul></ul><ul><li>New sources of data </li></ul><ul><ul><li>HARP </li></ul></ul><ul><ul><li>NA49 (P322) </li></ul></ul><ul><ul><li>E907 </li></ul></ul>HARP P322
  11. 11. Geomagnetic cutoffs & E-W effect as a consistency check <ul><li>Picture shows: </li></ul><ul><ul><li>20 GeV protons in geomagnetic equatorial plane </li></ul></ul><ul><ul><li>arrive from West and from near the vertical </li></ul></ul><ul><ul><li>but not from East </li></ul></ul><ul><li>Comparison to data: </li></ul><ul><ul><li>provides consistency test of data & analysis </li></ul></ul>From cover of “ Cosmic Rays ” by A.M. Hillas (1972) N
  12. 12. Response functions, sub-GeV  <ul><li>E primary ~ 10-20 x E  </li></ul><ul><li>Up/down ratio opposite at Kamioka vs Soudan/SNO </li></ul>
  13. 13. Cutoffs at Super-K <ul><li> flux, 0.4 < E  < 3 GeV </li></ul><ul><li>-0.5 < cos(  ) < 0.5 </li></ul><ul><li>measured by Super-K and compared to 3 calculations </li></ul>Measurement of East-West effect with atmospheric neutrinos--an important confirmation of analysis & interpretation of Super-K data as neutrino oscillations Lipari 3D Honda Bartol N E S W
  14. 14. 3-dimensional effects <ul><li>Characteristic 3D feature: </li></ul><ul><ul><li>excess of  near horizon </li></ul></ul><ul><ul><li>shown in top, left panel </li></ul></ul><ul><ul><li>lower panels show directions of  and e </li></ul></ul><ul><ul><li>cannot see 3D effect directly; however: </li></ul></ul><ul><li>Horizontal excess is associated with a change in path-length distribution </li></ul>From Battistoni et al., Astropart. Phys. 12 (2000) 315    
  15. 15. 3-D effects at Super-K <ul><li>3D--1D comparison (pink--blue/green) at Kamioka </li></ul><ul><li>Dip near horizon: </li></ul><ul><ul><li>due to high local horizontal cutoffs </li></ul></ul><ul><li>Size of effect: </li></ul><ul><ul><li>p T (  )/E  sets scale </li></ul></ul><ul><ul><li>~ 0.1 GeV / E  </li></ul></ul><ul><ul><li>therefore negligible for E  > 1 GeV </li></ul></ul>from M. Honda et al., Phys. Rev. D64 (2001) 053001
  16. 16. Path-length dependence <ul><li>Path length shorter near horizon on average in 3D case </li></ul><ul><ul><li>cos(  ) > 0 only, </li></ul></ul><ul><ul><li>phase space favors nearby interaction scattering to large angle </li></ul></ul><ul><ul><li>5-10% (E  ~0.3-1 GeV) </li></ul></ul><ul><li>Effect not yet included in Super-K analysis </li></ul>from M. Honda et al., Phys. Rev. D64 (2001) 053001 E  = 0.3 GeV E  = 1 GeV Soudan/SNO Kamioka <ul><ul><li> m 2 L/E …increase  m 2 1%? </li></ul></ul>
  17. 17. <ul><ul><li>Cosmic-ray albedo beautifully measured by AMS at 380 km </li></ul></ul><ul><ul><li>Biggest effect near geomagnetic equator (vertical cutoff ~ 10 GV) </li></ul></ul><ul><ul><li>Albedo: sub-cutoff protons from grazing interactions of cosmic rays > cutoff (S.B. Treiman, 1953) </li></ul></ul><ul><ul><li>trapped for several cycles </li></ul></ul><ul><ul><li>Re-entry rate is low (dashed line) </li></ul></ul>Is the second spectrum important for atmospheric  ? 10 GV P. Zuccon et al.
  18. 18. Technical aspects of 3D calculation <ul><li>Brute force </li></ul><ul><ul><li>Generate showers randomly all over globe </li></ul></ul><ul><ul><li> ~ A detector /A earth ~ 10 -10 </li></ul></ul><ul><ul><li>Use large A eff </li></ul></ul><ul><ul><ul><li>Lipari, Waltham </li></ul></ul></ul><ul><li>Neglect bending in geomagnetic field </li></ul><ul><ul><ul><li>Battistoni et al. </li></ul></ul></ul><ul><li>DST approach: two passes </li></ul><ul><ul><li>Giles Barr et al. </li></ul></ul><ul><ul><li>Equivalent to brute force but with higher efficiency,  ~ ? </li></ul></ul>
  19. 19. Higher energy atmospheric  <ul><li>Mean E  ~ 100 GeV for  -induced upward  </li></ul>
  20. 20. High energy ( e.g.      ) <ul><li>Importance of kaons </li></ul><ul><ul><li>main source of  > 100 GeV </li></ul></ul><ul><ul><li>p  K + +  important </li></ul></ul><ul><ul><li>Charmed analog important for prompt leptons </li></ul></ul>vertical 60 degrees
  21. 21. Calibration with atmospheric  <ul><li>MINOS, etc. </li></ul><ul><li>Neutrino telescopes </li></ul><ul><li>Example *** of   /  e </li></ul><ul><ul><li>flavor ratio </li></ul></ul><ul><ul><li>angular dependence </li></ul></ul>*** Note: this is maximal effect: horizontal = 85 - 90 deg in plots
  22. 22. MINOS:  + /  - discrimination 1 < E  < 70 GeV <ul><li>Events in 5 yr w / wo osc. </li></ul><ul><li>Contained + 400 / 260 </li></ul><ul><li>Contained - 620 / 440 </li></ul><ul><li>External + 160 / 120 </li></ul><ul><li>External - 400 / 280 </li></ul>TKG & Todor Stanev astr0-ph/0210512 a) No Oscillations b) Oscillations: full mixing,  m 2 = 0.0025eV 2   1 GeV contained 10 GeV, contained External (x 10 -4 ) Angular distribution of   
  23. 23. Vertically upward interactions inside detector E  E  E  Nine angular bins in  direction Problems:    smears effect; statistics too low in MINOS              so      - d   /dy ~ const, but d   /dy ~ (1-y) 2 , so      oscillates vs E   -
  24. 24. Global view of atmospheric  spectrum Uncertainty in level of charm a potential problem for finding diffuse neutrinos Prompt   e Solar    Plot shows sum of neutrinos + antineutrinos Slope = 3.7 Slope = 2.7 Possible E -2 diffuse astrophysical spectrum (WB bound)
  25. 25. Uncertainties & absolute normalization <ul><li>Primary spectrum </li></ul><ul><ul><li>+/- 10% up to 100 GeV (using AMS, BESS only) </li></ul></ul><ul><ul><li>+/- 20% below 100 GeV, +/- 30% ~TeV (all data) </li></ul></ul><ul><ul><li>Note lack of measurements in TeV range </li></ul></ul><ul><li>Hadronic interactions </li></ul><ul><ul><li>+/- 15% below 100 GeV </li></ul></ul><ul><ul><li>1D o.k. for comparing calculations and for tracking effects of uncertainties in input </li></ul></ul><ul><ul><li>Other sources at per cent level </li></ul></ul><ul><ul><ul><li>(local terrain, seasonal variations, anisotropy outside heliosphere) </li></ul></ul></ul><ul><ul><li>New measurements: HARP, E907, P322 </li></ul></ul><ul><li>Uncertainty in   </li></ul>
  26. 26. Summary (low energy) <ul><li>Evidence for  oscillation uses ratios: </li></ul><ul><ul><li>Contained events </li></ul></ul><ul><ul><ul><li>(     ) data / (  e /   ) calculated </li></ul></ul></ul><ul><ul><ul><li>upward / downward </li></ul></ul></ul><ul><ul><li>Neutrino-induced upward muons </li></ul></ul><ul><ul><ul><li>stopping / through-going </li></ul></ul></ul><ul><ul><ul><li>vertical / horizontal </li></ul></ul></ul><ul><ul><li>Broad response functions minimize dependence on slope of primary spectrum </li></ul></ul><ul><li>Uncertainties tend to cancel in comparison of ratios </li></ul><ul><li>Observation of geomagnetic effects confirms experiment & interpretation </li></ul>
  27. 27. Summary (high energy) <ul><li>Kaon decays  dominate atmospheric   ,  e above 100 GeV </li></ul><ul><li>Well-understood atmospheric   ,  e useful for calibration </li></ul><ul><li>Uncertainty in level of prompt neutrinos (from charm decay) will limit search for diffuse astrophysical neutrinos </li></ul>
  28. 28. What next? <ul><li>Use neutrino fluxes for calibration, etc. </li></ul><ul><ul><li>MINOS, SNO, Neutrino telescopes… </li></ul></ul><ul><ul><li>Learn about charmed analog of K  production </li></ul></ul><ul><li>Finish and use Giles’ 3D scheme </li></ul><ul><li>Incorporate new hadro-production results </li></ul><ul><ul><li>HARP below 15 GeV </li></ul></ul><ul><ul><li>NA 49, E907 ~ 100 GeV </li></ul></ul>
  29. 29. Comparison to muons <ul><ul><li> + ,  - vs atmospheric depth </li></ul></ul><ul><ul><li>newer measurements lower by 10-15% than earlier </li></ul></ul><ul><ul><li>comparison not completely internally consistent: </li></ul></ul><ul><ul><ul><li>ascent vs float </li></ul></ul></ul><ul><ul><ul><li>balloons rise rapidly </li></ul></ul></ul><ul><ul><ul><li>fraction detected is small compared to  decayed to  </li></ul></ul></ul>Data from CAPRICE, 3D calculation of Engel et al. (2001)
  30. 30. Solar modulation <ul><li>Neutron monitors </li></ul><ul><ul><li>well correlated with cosmic-ray flux </li></ul></ul><ul><ul><li>provide continuous monitor </li></ul></ul><ul><ul><li>response like sub-GeV neutrinos with no cutoff </li></ul></ul><ul><ul><li>SNO, Soudan: <20% variation </li></ul></ul><ul><ul><li>Kamioka: <5% (10 %) for downward (upward) </li></ul></ul>P. Lipari
  31. 31. a) No Oscillations b) Oscillations: full mixing  m 2 = 0.0025 eV 2   1 GeV contained 10 GeV, contained External (x 10 -4 ) Angular distribution of   
  32. 33. Soudan 5.9 kT yr Black lines: calculated, no oscillation Blue lines: fitted with oscillations M. Goodman, Neutrino 2002 Electrons Muons

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