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NOnA in the context of of future n oscillations projects

NOnA in the context of of future n oscillations projects. Leslie Camilleri CERN, PH Lausanne, May 15, 2006. Plan of the talk. A very brief theory of neutrino oscillations.

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NOnA in the context of of future n oscillations projects

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  1. NOnA in the context of of future n 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-b decay Reactors Accelerator long baseline experiments. • NOnA

  3. Theory 2

  4. Theory 3

  5. The PAST Discovery of Oscillations

  6. Solar spectrum

  7. Charged Current (CC) reactions on nucleons • ne + n  p + e-At quark level ne + d  u + e- • Sensitive ONLY tof(ne),the flux of ne • Neutral Current (NC) reactions on nucleons nx + n  n + nx Sensitive to flux from ALL flavours, f(ne, nm, nt) Real Time 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. Sensitiveto f(ne) only • Elastic Scattering (ES) on electron: ES is large in WATER and HEAVY WATER Sensitive to flux from ALL flavours, f(ne, nm, nt) But rate smaller than W exch.

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

  9. 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” ?

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

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

  12. Atmospheric Neutrinos: ne and nm Produced by p and K decays in upper atmosphere Zenith angle  Baseline

  13. Detect through neutrinos through their charged current interactions. nmX  m + … ne X  e + … m/e identification: Super-Kamiokande • sharp ring e fuzzy ring due to many particles in shower

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

  15. Suppression of nmin accelerator experiments: K2K, MINOS They look for nm disappearance to observe oscillatory pattern in energy spectrum. Measure Dm2 and q23 MINOS(NUMI beam) 732km K2K232 km Fermilab to Soudan Mine Same beam as NOnA. Will concentrate on MINOS KEK to SuperKamiokande Water Cerenkov Detector

  16. The MINOS/NOnA Neutrino beam: NUMI. Move horn and target to change energy of Beam

  17. MINOS detector

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

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

  20. New MINOS measurements (Experiment ended)

  21. 3-family oscillation matrix S = sine c = cosine • dCP violation phase. • q12drives SOLAR oscillations: sin2q12 = 0.314 +0.056-0.047(+- 16%) • q23drives ATMOSPHERIC oscillations: sin2q23 = 0.44 +0.18-0.10 (+44% -22%) • q13the MISSING link ! sin2 q13< 0.03Set by a reactor experiment: CHOOZ.

  22. Excellent source of MeV antineutrinos. • If they oscillate to nmor ntthey would NOT have enough energy to create • m’s or t’s via CC interactions. • Cannot study oscillations through an “appearance” experiment. • Must study oscillations via ne disappearance. • Pee = 1 – sin2 2q13sin2 [(Dm232L)/(4En)] SameDm2 as atmospheric. • With a detector at 1 km, L/E = 1km/1MeV ~ same as atmospheric ~ 1000km/1GeV. • Can probe same Dm2 CHOOZ: A reactor experiment to measure q13 Distortion of the ne energy spectrum Oscillation effects are SMALL Must know neenergy spectrum well to control SYSTEMATIC CHOOZ Systematic uncertainty: 2.7% Mostly from flux and n cross sections.

  23. Prompt _ g n e+ 511 keV e+ e- p p g n 511 keV ~200 ms g n 2.2 MeV p Delayed Technique Measured through inverse b decay: ne + p = e+ + n • Detectors : Liquid scintillator loaded with gadolinium: Neutron capture  photons e+ annihilates with e- of liquid: MeV ne n captured by Gadolinium: 8 MeV of photons emitted within 10’s of msec. Delayed Coincidence of 2 signals Did NOT find any distrortions. Set an upper limit: sin22q13 < 0.12 or sin2q13 < 0.03 for Dm2atm = 2.5 x 10-3 eV2

  24. ne nm nt Mass hierarchySign of Dm223 Normal Hierarchy Inverted Hierarchy Dm122 = 7.9 x 10 -5 eV2 m3 m2 m1 > 0.05 eV2 Dm232= 2.4 x 10-3 eV2 Dm232= 2.4 x 10-3 eV2 m2 m1 Dm122 = 7.9 x 10 -5 eV2 m3 Oscillations only tell us about DIFFERENCES in masses Not the ABSOLUTE mass scale: Direct measurements or Double b decay Upper limit: Tritium b decay: mass (ne) < 2.2 eV Lower limit: (2.4 x 10-3)1/2> 0.05 eV

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

  26. What’s needed next? • Determine q13. • Determine the mass hierarchy. • Any CP violation in the neutrino sector?

  27. Correlations in Oscillation Probability From M. Lindner: Measuring P (nm~ne) does NOT yield a UNIQUE value of q13. Because of correlations between q13, dCPand the mass hierarchy (sign of Dm231) CP violation: Difference between Neutrino and Antineutrino Oscillations Mass hierarchy accessible through Matter effects.

  28. 8-fold degeneracies • q13 - d ambiguity. • Mass hierarchy two-fold degeneragy A measure of Pme can yield a whole range of values of q13 Measuring with n’s as well reduces the correlations • q23 degeneracy: • For a value of sin2 2q23, say 0.92, 2q23is 67o or 113 o and q23 is 33.5o or 56.5 • In addition if we just have a lower limit on sin2 2q23, then all the values between these two are possible.

  29. Matter Effects In vacuum and without CP violation: P(nm-ne)vac = sin2q23 sin2 2q13 sin2 Datm withDatm= 1.27 Dm232 (L/E) For Dm232 = 2.5 x 10-3 eV2 and for maximum oscillation • We need: Datm = p/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(nm-ne)mat = [1 +- (2E/ER)] P(nm-ne)vac withER = [12 GeV][Dm232/(2.5x10-3)][2.8 gm.cm-3/r]~ 12 GeV +-depends on the mass hierarchy. Matter effects grow with energy and therefore with distance. 3times larger (27%) at NOnA (1.64 GeV) than at T2K (0.6 GeV)

  30. The NEAR Future

  31. Neutrinoless Double-b decay (A,Z)  (A,Z+2) + 2 e- (A,Z)  (A,Z+2) + 2 e- + 2n Standard 2-neutrino double b decay Neutrinoless double b 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 e- e- e- e- ni ni ni N N´ W- W- W- W- N N´

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

  33. q13 with Reactors: How to reduce systematics Pee = 1 – sin2 2q13sin2 [(Dm232L)/(4En)] near oscillation maximum Advantage: NO dependence ondCPor mass hierarchy: No ambiguities. • 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 Disadvantage: Cannot determine them! How to reduce systematics ?

  34. Proposed experiments CHOOZ systematics was 2.7%

  35. Future (Accelerators) T2K (Japan) 295km NOnA (NUMI beam) 810km Both projects are Long Baseline Off-axis projects. They search for nm ~ neoscillations by searching for neappearance in a nm beam. Determine that q13is non-zero. Measure it? Mass hierarchy?

  36. Super-K. q Decay Pipe Target Horns OFF-AXIS Technique Most decay pions give similar neutrino energies at the detector: The Neutrino Energy Spectrum is narrow: know where to expect neappearance Can choose the off-axis angle and select the mean energy of the beam. ( Optimizes the oscillation probability) q = 0o q = 2o q = 3o

  37. 0.7 GeV T2K • 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 nm ne ne from K decays (hashed) and m decays 0.4 %background at peak . Irreducible background to a nm ne search.

  38. nm disappearance: Dm232 and q23. Position of dip Dm232 to an accuracy of ~ 10-4 eV2 Depth of dip Sin22q23to an accuracy of 0.01 Factor of 10 improvement in both

  39. Measurement of q13. ne appearance

  40. Sensitivity, correlations, degeneracies Limit on sin2 2q13 if we take into account correlations and degeneracies Sin2 2q13 ~ 0.01 - 0.04 -150 0 dCP150

  41. All degeneracies included T2K II: Hyper-Kamiokande One megaton Water Cerenkov and 4MW accelerator. Improvement by more than an order of magnitude on q13 sensitivity 0.01 sin22q13 0.001 -150o d +150o

  42. T2K II: Sensitivity to dCP Definition: For each value of sin2 2q13: The minimum d for which there is a difference Of 3s between CP and NO CP violation Limited by statistics d 50o 20o CP violation asymmetry (n,n difference) decreases with increasing sin2 2q13 0.0001 0.01 Sin2 2q13

  43. NOnA Detector Given relatively high energy of NUMI beam, decided to optimize NOnAfor 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 TiO2 Coated PVC tubes n

  44. NOnA 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

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

  46. 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.

  47. The Proton Beam as of today 2.8 x 1013 p’s per spill (2.2 secs) For a Fermilab year of 2 x 107 secs 2.4 x 1020 pots/year. MINOS baseline 3.4 x 1020 pots/year.

  48. The Beam • PROTONS: 6.5 x 1020 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 1020 • Longer term: Construction of an 8 GeV proton driver: x 4 • 25.2 x 1020 protons on target per year is the goal.

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