1.  in the context of of future oscillations projects Leslie Camilleri CERN, PH Lausanne, May 15, 2006

2. Plan of the talk A very brief theory of neutrino oscillations. The Past: The discovery of oscillations in Solar and Atmospheric neutrino experiments. The Present programmes: Double-  decay Reactors Accelerator long baseline experiments. NO A

4. Theory 2

5. Theory 3

6. The PAST Discovery of Oscillations

7. Solar spectrum

9. Real Time  Charged Current (CC) reactions on nucleons  e + n  p + e - At quark level e + d  u + e- Sensitive ONLY to  e  the flux of e  Neutral Current (NC) reactions on nucleons x + n  n + x Sensitive to flux from ALL flavours,  e, ,   CC and NC on nucleons: negligible in WATER due to Oxygen being very tightly bound (>15 MeV) Important in HEAVY WATER: deuterium binding energy only 2 MeV.  Elastic Scattering (ES) on electron: ES is large in WATER and HEAVY WATER Sensitive to  ( e ) only Sensitive to flux from ALL flavours,  ( e, ,  ) But rate smaller than W exch.

10. Super-Kamiokande The Detector 50000 tons ultra-pure water 1 km overburden = 2700 m.w.e. 22500 tons fiducial volume Sensitive to Elastic Scattering ONLY Mostly e ’s

11. Suppression relative to Standard Solar Model Suppression relative to Standard Solar Model is observed in all experiments. Is it due to a misunderstanding as to how the sun “works” ? Standard solar model. Or are the neutrinos “disappearing” ?

12. SNO (Heavy water):Sensitive to CC, NC, ES. Calculate flux from each. Flavor content of solar flux. e only e mostly e     Neutrinos DO NOT disappear. They just Change Flavour ! Driven by enhanced oscillations in the dense matter of the sun. Using ALL neutrinos Fully Consistent with Standard Solar Model NC ES SK ES CC SSM   ee

13. Confirmed by KAMLAND: Reactor antineutrinos to detector at Kamioka Solar Experiments KAMLAND KamLAND + Solar Completely consistent

14. Atmospheric Neutrinos: e and   Zenith angle  Baseline Produced by  and K decays in upper atmosphere

15.  /e identification: Super-Kamiokande  sharp ring e fuzzy ring due to many particles in shower Detect through neutrinos through their charged current interactions.   X   … e X  e + …

16. Suppression of  zenith angle and energy dependent Explained by oscillations Similar results from MACRO No oscillations Oscillations

17. Suppression of  in accelerator experiments: K2K, MINOS MINOS (NUMI beam) 732km They look for  disappearance to observe oscillatory pattern in energy spectrum. Measure  m 2 and  23 K2K 232 km KEK to SuperKamiokande Water Cerenkov Detector Fermilab to Soudan Mine Same beam as NO A. Will concentrate on MINOS

18. The MINOS/NO A Neutrino beam: NUMI. Move horn and target to change energy of Beam

19. MINOS detector

20. Near detector results The NUMI beam is well understood.

21. Far detector results II Suppression of events at low energy Ratio of Observed over Expected with no oscillations

22. New MINOS measurements ( Experiment ended)

23. 3-family oscillation matrix S = sine c = cosine   CP violation phase.    drives SOLAR oscillations: sin 2  12 = 0.314 +0.056 -0.047 (+- 16%)   23 drives ATMOSPHERIC oscillations: sin 2  23 = 0.44 +0.18 -0.10 (+44% -22%)   13 the MISSING link ! sin 2  13 < 0.03  Set by a reactor experiment: CHOOZ.

24. CHOOZ: A reactor experiment to measure  13  Excellent source of MeV antineutrinos.  If they oscillate to   or   they would NOT have enough energy to create  ’s or  ’s via CC interactions.  Cannot study oscillations through an “appearance” experiment.  Must study oscillations via e disappearance. P ee = 1 – sin 2 2  13 sin 2 [(  m 23 2 L)/(4E )] Same  m 2 as atmospheric.  With a detector at 1 km, L/E = 1km/1MeV ~ same as atmospheric ~ 1000km/1GeV.  Can probe same  m 2 Distortion of the e energy spectrum Oscillation effects are SMALL Must know e energy spectrum well to control SYSTEMATIC CHOOZ Systematic uncertainty: 2.7% Mostly from flux and  cross sections.

25. Technique Detectors : Liquid scintillator loaded with gadolinium: Neutron capture  photons p p e+e+  e-e- e+e+   511 keV n n p  2.2 MeV ~200 s e e + annihilates with e - of liquid: MeV n captured by Gadolinium: 8 MeV of photons emitted within 10’s of  sec. Delayed Coincidence of 2 signals Measured through inverse  decay: e + p = e + + n Did NOT find any distrortions. Set an upper limit: sin 2 2  13 < 0.12 or sin 2  13 < 0.03 for  m 2 atm = 2.5 x 10 -3 eV 2

26. Mass hierarchy Sign of  m 2 23 m2m1m2m1 m3m3 m2m1m2m1 m3m3  m 23 2 = 2.4 x 10 -3 eV 2  m 23 2 = 2.4 x 10 -3 eV 2  m 12 2 = 7.9 x 10 -5 eV 2 > 0.05 eV 2 Normal Hierarchy Inverted Hierarchy Oscillations only tell us about DIFFERENCES in masses Not the ABSOLUTE mass scale: Direct measurements or Double  decay Upper limit: Tritium  decay: mass ( e ) < 2.2 eV Lower limit: (2.4 x 10 -3 ) 1/2  > 0.05 eV  m 12 2 = 7.9 x 10 -5 eV 2 e  

27. Why are neutrino masses so low???? Other particles Fascinating to me !!!!!!

28. What’s needed next?  Determine  13.  Determine the mass hierarchy.  Any CP violation in the neutrino sector?

29. Correlations in Oscillation Probability From M. Lindner: Measuring P (  ~ e ) does NOT yield a UNIQUE value of  13. Because of correlations between  13,  CP and the mass hierarchy (sign of  m 2 31 ) CP violation: Difference between Neutrino and Antineutrino Oscillations Mass hierarchy accessible through Matter effects.

30. 8-fold degeneracies   13 -  ambiguity.  Mass hierarchy two-fold degeneragy A measure of P  e can yield a whole range of values of  13 Measuring with ’s as well reduces the correlations   23 degeneracy: For a value of sin 2 2  23, say 0.92, 2  23 is 67 o or 113 o and  23 is 33.5 o or 56.5  In addition if we just have a lower limit on sin 2 2  23, then all the values between these two are possible.

31. Matter Effects In vacuum and without CP violation: P(   e ) vac = sin 2  23 sin 2 2   sin 2  atm with  atm = 1.27  m 2 32 (L/E) For  m 2 32 = 2.5 x 10 -3 eV 2 and for maximum oscillation  We need:  atm =  /2  L(km)/E(GeV) = 495 For L = 800km E must be 1.64 GeV, and for L = 295km E = 0.6 GeV Introducing matter effects, at the first oscillation maximum: P(   e ) mat = [1 +- (2E/E R )] P(   e ) vac with E R = [12 GeV][  m 2 32 /(2.5x10 -3 )][2.8 gm.cm -3 /  ]~ 12 GeV +- depends on the mass hierarchy. Matter effects grow with energy and therefore with distance. 3 times larger (27%) at NO A (1.64 GeV) than at T2K (0.6 GeV)

32. The NEAR Future

33. Neutrinoless Double-  decay e-e- e-e- W-W- W-W- e-e- e-e- i W-W- W-W- N N´N´ N´N´ N Standard 2-neutrino double  decay Neutrinoless double  decay Can only happen if the neutrino is reabsorbed as an Antineutrino Helicity must flip  non-zero mass If the neutrino is its own Antiparticle: Majorana i i (A,Z)  (A,Z+2) + 2 e - (A,Z)  (A,Z+2) + 2 e - + 2

34. Detection arbitrary units (Q  ~ MeV) Look for a peak at the end point of the2-neutrino spectrum New experiments will use: 130 Te, 132 Xe, 76 Ge, 100 Mo Will observe the 2 electrons through bolometric, calorimetric or tracking techniques Sensitivity down to 100-300 meV

35.  13 with Reactors: How to reduce systematics Solution: Use 2 detectors Additional NEAR detector: measure flux and cross sections BEFORE oscillations. Even better: interchange NEAR and FAR detectors part of the time to reduce detector systematics P ee = 1 – sin 2 2  13 sin 2 [(  m 23 2 L)/(4E )] near oscillation maximum Advantage: NO dependence on  CP or mass hierarchy: No ambiguities. Disadvantage: Cannot determine them! How to reduce systematics ?

36. Proposed experiments ExperimentLocation SitesSystematicsLimit Double CHOOZFranceNear/Far0.6%0.03 BraidwoodUSANear/Far0.3%0.005 Daya BayChinaNear/Mid/Far0.36-0.12%0.009-0.006 CHOOZ systematics was 2.7%

37. Future (Accelerators) T2K (Japan) 295km NO A (NUMI beam) 810km Both projects are Long Baseline Off-axis projects. They search for  ~ e oscillations by searching for e appearance in a  beam. Determine that    is non-zero  Measure it? Mass hierarchy?

38. OFF-AXIS Technique Most decay pions give similar neutrino energies at the detector: The Neutrino Energy Spectrum is narrow: know where to expect e appearance Can choose the off-axis angle and select the mean energy of the beam. ( Optimizes the oscillation probability)  Target Horns Decay Pipe Super-K.    2 o  3 o

39. T2K  0.7 GeV  e from K decays (hashed) and  decays 0.4 %  background at peak. Irreducible background to a   e search. e  New 40 GeV Proton Synchrotron (JPARC)  Reconstructed Super-K  Near detector to measure unoscillated flux distance of 280 m (Maybe 2km also)  JPARC ready in 2008  T2K construction 2004-2008  Data-taking starting in 2009

40.  disappearance:  m 23 2 and  23. Position of dip  m 23 2 to an accuracy of ~ 10 -4 eV 2 Depth of dip Sin 2 2  23 to an accuracy of 0.01 Factor of 10 improvement in both

41. Measurement of  13. e appearance

42. Sensitivity, correlations, degeneracies Limit on sin 2 2   if we take into account correlations and degeneracies Sin 2 2  13 ~ 0.01 - 0.04  CP 150

43. T2K II: Hyper-Kamiokande One megaton Water Cerenkov and 4MW accelerator.  0.01 0.001  +150 o -150 o sin 2 2  13 Improvement by more than an order of magnitude on  13 sensitivity All degeneracies included

44. T2K II: Sensitivity to  CP Definition: For each value of sin 2 2  13 : The minimum  for which there is a difference Of 3  between CP and NO CP violation Limited by statistics CP violation asymmetry (  difference) decreases with increasing sin 2 2  13 Sin 2 2  13 0.01 0.0001 20 o 50 o 

45. NO A Detector Given relatively high energy of NUMI beam, decided to optimize NO A  for resolution of the mass hierarchy Detector placed 14 mrad (12 km) Off-axis of the Fermilab NUMI beam (MINOS). At Ash River near Canadian border (L = 810km) : New site. Above ground. Fully active detector consisting of 15.7m long plastic cells filled with liquid scintillator: Total mass 30 ktons. Each cell viewed by a looped WLS fibre read by an avalanche photodiode (APD) 760 000 cells TiO 2 Coated PVC tubes

46. NO A The quantum efficiency of APD’s is much higher than a pm’s: ~80%. Especially at the higher wave lengths surviving after traversing the fibre. Asic for APD’s: 2.5 pe noise  S/N ~ 12

47. Avalanche Photodiode  Hamamatsu 32 APD arrays  Pixel size 1.8mm x 1.05mm (Fibre 0.8mm diameter)  Operating voltage 400 Volts  Gain 100  Operating temperature: -15 o C (reduces noise) Photon Asic for APD’s: 2.5 pe noise  S/N ~ 30/2.5 = 12

48. Fibre/Scintillator cosmic ray test Inserted looped 15.7m long fibre in 60 cm long PVC tube filled with liquid scintillator. Exposed to cosmic rays. Measured 20 p.e. For a mip signal at the far end.

49. The Proton Beam as of today 2.8 x 10 13 p’s per spill (2.2 secs) For a Fermilab year of 2 x 10 7 secs 2.4 x 10 20 pots/year. MINOS baseline 3.4 x 10 20 pots/year.

50. The Beam PROTONS: 6.5 x 10 20 protons on target per year. Greatly helped by  Cancellation of BTeV  Termination of Collider programme by 2009. A gain of a factor of > 2 in numbers of protons delivered. As of today, this extrapolates to: 4.8 x 10 20 Longer term: Construction of an 8 GeV proton driver: x 4 25.2 x 10 20 protons on target per year is the goal.

51. The Beam: Same NUMI beam as MINOS 14 mrad Can select low, medium and high energy beams by moving horn and target Best is the Medium energy beam

52. Beam spectra Signal Sin 2 2  13 = 0.04 Beam e background ~ 0.5%   

53.   e separation Electrons (shower) Electrons (shower) Muons Low energyHigh energy  o in NC also a problem. Signal e efficiency: 24%.  CC background 4 x 10 -4  NC background 2 x 10 -3

54. Summary of backgrounds BackgroundEvents% ErrorError Beam e 11.97%0.8   CC 0.515%0.08 NC7.15%0.4 Total19.55%0.9

55. Signal and Backgrounds Statistical Power: why this is hard and we need protons For sin 2 2  13 = 0.1: : S=142.1, B=19.5 : S= 71.8, B=12.1 5 yrs at 6.5E20 pot/yr, efficiencies included 0.010.05 0.1

56. 3  discovery limits for  13 = 0 Discovery limit is better than 0.02 for ALL  ’s  and BOTH mass hierarchies. 2.5 years each and . 5 years

57. 3  discovery limits for  13 = 0 Comparison with Proton Driver 2.5 years each and .

58. 3  discovery limits for  13 = 0 Comparison with T2K and 2 Reactor experiments Braidwood Double Chooz T2K

59. Resolution of mass hierarchy  Fraction of  over which the mass hierarchy can be resolved at    qual amounts of neutrino and antineutrino running: 3 years each assuming Phase I.  Near the CHOOZ limit the mass hierarchy can be resolved over 50% of the range of .  T2K Phase I can only resolve the hierarchy in a region already excluded by CHOOZ. Because of its lower energy.  Some small improvement if we combine T2K and NO A results CHOOZ limit T2K

60. Looking further ahead  With a proton driver, Phase II, the mass hierarchy can be resolved over 75% of  near the CHOOZ limit.  In addition to more protons in Phase II, to resolve hierarchy a second detector at the second oscillation maximum can be considered:   atm = 1.27  m 2 32 (L/E) =   L/E = 1485, a factor of 3 larger than at 1 st max.  For ~ the same distance, E is 3 times smaller:  matter effects are smaller by a factor of 3  50 kton detector at 710 km.  30km off axis (second max.)  6 years (3  + 3 ) Determines mass hierarchy for all values of  down to sin 2 2  13 = 0.02

61. CP reach  To look for CP violation requires the proton driver.  But combining with a second detector is what really becomes SIGNIFICANT. Proton driver Proton driver + 2 nd detector

62. Near Detector to understand the beam 262 T 145 T totally active 20.4 T fiducial (central 2.5 x 3.25 m) 8-plane block 10.6 T full 1.6 T empty Muon catcher 1 m iron Target region Veto region 9.6 m 5 m 3.5 m Shower containment region

63. Neutrino spectra at near and far detectors  CC events e CC events Far Detector x 800 Site 1.5 Site 2

64. Cost and schedule  Total cost (Far and near detectors, building, admin etc…) 225 M$ (including 50% contingency) Status  Approved by Fermilab Program Advisory Committee: Stage 1 Approval, (April 2005).  Prioritized by NuSAG.  Critical Decision Zero (CD0) granted. Mission need.  Granted $10M in R&D for generic oscillation experiment.  Obtained CD1 approval: Range of Schedules and costs.  CD2 next: Final cost, schedule and TDR.  Proton Driver CD0 shelved at this stage. But R&D can continue. Schedule  Assumption: Approval in 2006.  Building ready: May 2009.  First kiloton: October 2009.  Completion: July 2011.  European groups already in NO A: Athens, College de France, Tech. Univ. Munich Italian groups possibly: Rome, Ferrara, Bologna, Padova,Pisa CERN ???

65. The road ahead

66. Conclusions  The neutrino oscillation programme is very rich.  The smallness of neutrino masses is fascinating.  The mass hierarchy must be determined.  Is there any CP violation in the neutrino sector?  The road to these is the observation of a non-zero     The NUMI beam is functioning well.  NO A has a well-developed long term research programme.

67. Near Detector in MINOS Surface Building 45,000   CC events2,200 e CC events 6.5 x 10 20 pot in 75 mrad off-axis beam Kaon peak

68. Matter effects: Mikheyev-Smirnov-Wolfenstein e     e e e    N ee ee All  flavours Only e  flavour Introduces extra potential for e ZoZo W-W-

69.  13 with Reactors P ee = 1 – sin 2 2  13 sin 2 [(  m 23 2 L)/(4E )] near oscillation maximum Advantage: NO dependence on  CP or mass hierarchy: No ambiguities. Disadvantage: Cannot determine them! Measured through inverse  decay: e + p = e + + n Distortion of the e energy spectrum Oscillation effects are SMALL Must know e energy spectrum well to control SYSTEMATICS. CHOOZ: One detector at 1100m Systematic uncertainty: 2.7%

70. SK-I: 8 B Solar Neutrino Flux 8 B flux = 2.35  0.02  0.08 [x10 6 /cm 2 /s] Data / SSM BP2004 = 0.406  0.004(stat.) +0.014 -0.013 (syst.) 22400  230 solar  events PLB539 (2002) 179 Electron total energy: 5.0-20MeV May 31, 1996 – July 15, 2001 (1496 days ) Data / SSM BP2000 = 0.465  0.005(stat.) +0.016 -0.015 (syst.)

71. Far detector results I In time with beam spill Uniform spatial distributions Intermodule gap

72. Limits Claim Rate = (T o ½ ) -1 = (Phase space factor) x (Matrix element) 2 x 2 = | U e1 2 m 1 + U e2 2 m 2 +U e3 2 m 3 | New experiments will go down 100-300 milli eV Small if m 3 is heaviest state, because multiplied by U e3 2 (= sin 2  13 ) which is small (<0.03). Better with inverted hierarchy

73. CHOOZ: Limits on  13 Set a limit on sin 2 2  13 < 0.12 for  m 2 atm = 2.5 x 10 -3 eV 2 or sin 2  13 < 0.03 Looked for distortions of the expected energy spectrum or in the rate Did not find any.

74. Detection arbitrary units (Q  ~ MeV) Look for a peak at the end point of the2-neutrino spectrum One claim: not generally believed New experiments will use: 130 Te, 132 Xe, 76 Ge, 100 Mo Will observe the 2 electrons through bolometric, calorimetric or tracking techniques Sensitivity down to 100-300 meV

75. Proposed experiments ExperimentLocation SitesSystematicsLimit Double CHOOZFranceNear/Far0.6%0.03 BraidwoodUSANear/Far0.3%0.005 Daya BayChinaNear/Mid/Far0.36-0.12%0.009-0.006 Example: Double CHOOZ 1% 0.4% Importance of systematics 0.035 0.027 CHOOZ systematics Was 2.7%