Neutrinos: Past, Present and Future

1. Neutrinos: Past, Present and Future Robert C. Webb Physics Department Texas A&M University

2. A Brief History of the Neutrino The Early Years…… • 1930 Pauli proposes a massless neutral particle. • 1932 Fermi names the “neutrino”. • 1956 The first observation of electron anti-neutrinos by Reines and Cowan. • 1957-62 Possibility that neutrinos oscillate proposed by Pontecorvo and Sakata. • 1961 The muon neutrino is observed at BNL. RCW PPC 2007

3. Discovering the Neutrino RCW PPC 2007

4. Neutrino Physics 1960-1990 • The observation of neutrinos by Reines and Cowan ushered in a new era of the study of these elusive “beasts” • Accelerator based measurements undertaken in the US and Europe. • Solar neutrino experiments begun underground. RCW PPC 2007

5. The triumph of the Electro-Weak Unification While experimentalists set out to study the neutrino, the theorist were busy trying to find a theory for the weak interactions of the neutrino that fit… Weinberg and Salam develop a possible candidate, but it requires a “neutral” weak current as the charged current already seen. RCW PPC 2007

6. Theory is working fine..but • The Solar Neutrino problem emerges. • Ray Davis and collaborators with encouragement from John Bachall search for neutrinos from the sun using a giant tank of “cleaning fluid”. (1968) • However, they “see” too few!! • What’s wrong, the theory or the experiment?? or both!! RCW PPC 2007

7. New experiments emerge to study this question. • All of these measurements found too few solar neutrinos!! • This question will get the ultimate answer in 2003 from the SNO Collaboration! RCW PPC 2007

8. It’s not just the solar neutrinos that are mis-behaving.. • There is an anomaly in the atmospheric neutrino flux as well. • SuperK along with several other undergound experiments see too few muon neutrinos!! RCW PPC 2007

9. Super K’s results (1998) • Things make sense if we allow for neutrinos to “oscillate”… RCW PPC 2007

10. Two neutrino mixing RCW PPC 2007

11. But neutrinos still aren’t cooperating • If there are only 3 neutrinos then there should only be two mass differences!! RCW PPC 2007

12. Neutrino mass and mixing RCW PPC 2007

13. “precision” experimentsto the rescue • NuMI/MINOS at Fermilab • K2K at KEK and in the future… T2K and NOVA RCW PPC 2007

14. MINOS overview • NUMI Beam Line • Near Detector • Far Detector • Beam running • Data Analysis RCW PPC 2007

15. protons The NuMI n beam : MI RCW PPC 2007

16. NuMI Beam Protons Delivered RCW PPC 2007

17. NuMI Beam Performance • Total Integrated POT as of now: >3 1020, have run at up to 310kW, and up to 4.0 1013 protons per pulse RCW PPC 2007

18. The 3 NuMI Beam Configurations RCW PPC 2007

19. MINOS Near Detector • 1 kton total mass • Same basic design steel, scintillator, etc • Some differences, e.g.: • Faster electronics • Partially instrumented: • 282 planes of steel • 153 planes of scintillator • (Rear part of detector • only used to track muons ) • +….. RCW PPC 2007

20. Typical Neutrino Beam Event RCW PPC 2007

21. Near Detector Events(showing multiple events in spill window) RCW PPC 2007

22. RCW PPC 2007

23. Near Detector CC events RCW PPC 2007

24. MINOS Far Detector Running since 2003!! RCW PPC 2007

25. The MINOS Far Detector • Currently have ~20 kt-yr of Cosmic Ray data. • Observing single and multiple muons. LOTS • Observed upward going muons (neutrino interaction below the detector). ~300 events in current sample. • First physics paper on beam neutrinos submitted to Phys. Rev. Lett. • In operation with >2 E 20 Protons on the NuMI target RCW PPC 2007

26. A beam neutrino event in the MINOS Far Detector RCW PPC 2007

27. RCW PPC 2007

28. RCW PPC 2007

29. RCW PPC 2007

30. Atmospheric neutrinos RCW PPC 2007

31. First results from MINOS RCW PPC 2007

32. MINOS data as a function of Energy RCW PPC 2007

33. MINOS Sensitivity RCW PPC 2007

34. The ultimate sensitivity RCW PPC 2007

35. Electron neutrino mixing..the next target • NOVA and T2K..using accelerator neutrinos. • Daya Bay and Double Chooz…using reactor neutrinos. RCW PPC 2007

36. The Off-Axis concept RCW PPC 2007

37. RCW PPC 2007

38. Beam Location and Far Detector Siting RCW PPC 2007

39. 15.7m 110m 15.7m NOvA Far Detector • 25 ktons • 1984 liquid scintillator planes, no additional absorber (~80% active) • Scintillator cells 3.8 x 6.0 x 1570 cm • Read out from one side per plane with APDs • Expected minimum signal 20pe RCW PPC 2007

40. nm + A -> p +m- ne+A→p p+p- e- n + A -> p + 3p± + p0 + n NOvA Event Simulations One unit is 4.9 cm (horizontal) 4.0 cm (vertical) Particle ID: particularly “fuzzy” e’s long track, not fuzzy (m) gaps in tracks ( po ?) large energy deposition (proton?) RCW PPC 2007

41. NOvA Near Detector • 126 tons of scintillator, 83 tons of steel • 23 ton fiducial mass • 186 liquid scintillator planes in target, 10 in muon ranger, 1m of steel • Same cell size, same minimum signal • Read out from one side per plane with APDs plus faster electronics than in far detector RCW PPC 2007

42. The Far Detector Site RCW PPC 2007

43. Upgrading Proton Source for NOvA • Proton Plan goal (present FNAL accelerator upgrade program) is 390kW (have achieved 310kW with MINOS) • Proton Plan 2 uses Recycler as a proton pre-injector • Post-collider era: Use Recycler to accumulate protons from Booster while MI is accelerating, saves time • Recycler momentum aperture is large enough to allow slip-stacking operation in Recycler for up to 12 Booster batches injected • Extracted to MI in a single turn and there re-captured and accelerated • Main Injector will run at its design acceleration rate of 240 GeV/s (1.333 s cycle time) • 4.3×1012 p/batch, 95% slip-stacking efficiency • 4.9×1013 ppp at 120 GeV every 1.333s  700 kW, or 6×1020protons per year Now part of NOvA Project! RCW PPC 2007

44. Neutrino Summary • MINOS data show nm disappearance at low energies at 6.2s (1.27x1020 Protons on Target) • The best fit oscillation parameters are (hep-ex 0607088) • Systematic uncertainties on Dm2 are ~40% of statistical • MINOS continues to take data—still to come: cross sections, ne appearance, sterile neutrino search RCW PPC 2007

45. NOvA Prospects • NOnA look for ne /nm transitions at Dm2atm • First hint of q13 being non-zero? • CP violation in absence of matter effects • Matter effects in absence of Dmsol2 RCW PPC 2007

46. Neutrino future outlookwhat might we expect to see 50 years hence? • New group of precision experiments b eing planned to study electron neutrino-muon neutrino mixing.. • Possibility that there is CP violation in the neutrino sector.. • Is the neutrino a Majorana particle or not?? • Large underground detectors will allow us to use neutrinos for the study of the earth, dark matter candidates, supernovae, and beyond… RCW PPC 2007