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Lectures on Neutrino Physics

Lectures on Neutrino Physics. Fumihiko Suekane Research Center for Neutrino Science Tohoku University suekane@awa.tohoku.ac.jp http://www.awa.tohoku.ac.jp/~suekane. France Asia Particle Physics School @Ecole de Physique Les Houchess 18-20/Oct./2011.

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Lectures on Neutrino Physics

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  1. Lectures on Neutrino Physics Fumihiko Suekane Research Center for Neutrino Science Tohoku University suekane@awa.tohoku.ac.jp http://www.awa.tohoku.ac.jp/~suekane France Asia Particle Physics School @Ecole de Physique Les Houchess 18-20/Oct./2011 suekane@FAPPS

  2. * This lecture is intended to give intuitive understanding of neutrino physics for students and young physicists of other field. * I will try to make this lecture to be a bridge between general text books and scientific papers. * 3 lectures are very short to mention about all the varieties of neutrino physics and only limited but important topics are mentioned. Scientific Papers This lectures Introduction to Particle Physics text books suekane@FAPPS

  3. Contents * History * Neutrinos in the Standard Model * Neutrino Oscillations (Main) * Double Beta decays * Prospects Day-1 Day-2 Day-3 suekane@FAPPS

  4. What is known for neutrinos PDG2010 Only a few things are known about neutrinos. .... There is much room to study. suekane@FAPPS

  5. Basic Fermion Strong Interaction YES NO Quark Lepton u,d,s,c,b,t EM Interaction YES NO Charged Lepton Neutrino e, m, t We call Fermions which do not perform strong nor EM interaction, Neutrinos suekane@FAPPS

  6. big bang n Neutrinos in Nature in early universe. Most abundant next to photons (~100n/cc)

  7. (years are approximate) n Timeline 1899 Discovery of b-decay [Rutherford] 1914 b-ray has continuous energy spectrum [Chadwick] 1930 Neutrino hypothesis [Pauli] 1st Evidence of neutrino @ reactor [Reines & Cowan] 1961 Discovery of nm [Shwartz, Ledermann, Steinberger] 1969~ Deficit of solar neutrino [Davis] Discovery of t lepton ( indirect evidence of nt ) [Perl] 1985 Proposal of MSW effect [Mikheyev, Smirnov, Wolfenstein] 1987 Detection of neutrinos from SN1987A [Koshiba] 1989 Nn=3 by Z0 shape [LEP] 1995 Nobel prize to Reines (1996, 1997Claim of nm->ne oscillation [LSND]) 1st evidence of neutrino oscillation by atmospheric n [SuperKamiokande] 2000 Direct evidence of nt [DONUT] (2001 Claim of neutrinoless bb decay [Klapdor]) 2002 Nobel prize to Davis & Koshiba 2002 Flavor transition [SNO] Reactor Neutrino Deficit [KamLAND] 2004 nm disappearance @ Accelerator [K2K] 2010 nmnt [OPERA] 2011 Indication of ne appearance @ Accelerator [T2K]

  8. M M’ m n Ta/g n Tb 1st Indication of Neutrino (The 1st anomaly in neutrino which lead great discovery.) ~1914, an anomaly found g & a decays  The energy of the decay particle is unique J.Chadwick, 1914 However, for b-decays, it is continuous. Why?? suekane@FAPPS

  9. A A’ b ν M M’ m Neutrino Hypothesis * Energy conservation low is broken （N.Bohr, 1932） Wikipedia * b-decay is a 3 body reaction (W.Pauli, 1930) Neutrino Hypothesis Wikipedia suekane@FAPPS

  10. 4/Dec./1930 Letter from Pauli to participants of a conference. suekane@FAPPS

  11. Expected properties of ν from b-decays (1) Q=0  charge conservation (2) s=1/2  spin conservation (3) mass is small if exists maximum energy of b-rays. (4) Interact very weakly  lifetime of b-decays. suekane@FAPPS

  12. How n-N cross section was estimated in early days. Fermi's model p p Dirac e p Fermi n GF e e- n Analogy e- e- Various -decays & Electron caputure GF~10-11/MeV2 Then, "I did something a physicist should never do. I predicted something which will never be observed experimentally..".（W.Pauli) "There is no practically possible way of observing the neutrino" (Bethe & Peierls, 1934) suekane@FAPPS

  13. Then 30 years had passed .... Discovery of n Very strong n sources are necessary,  Chain reactions of nuclear fissions. Energy release: b-decays: 200MeV/fission ~ 6 n/fission 1.9x1011n/J Reactor or Nuclear Explosion En~ MeV suekane@FAPPS

  14. An early idea to detect n (not realized) by Reines & Cowan Reines & Cowan Nuclear Explosion Vacuum shaft Neutrino Detector Free fall to prevent the shock wave. => Physicists make use of everything available While preparing the experiment, they realized nuclear reactor is more relevant to perform experiment. suekane@FAPPS

  15. Then they moved to a Savannah River Reactor 200L Cd loaded water tanks 1400L liquid scintillator tanks P=700MW 1982 Wikipedia suekane@FAPPS

  16. Principle of n detection * n flux: @15m from Savannah Liver P reactor core. (P=700MW) flux~5x1012n/cm2/s * Detection Principle: n e+ Delayed Coincidence Technique Still used in modern experiments ~10ms suekane@FAPPS

  17. 2 examples of delayed coincidence LS tank ID http://library.lanl.gov/cgi-bin/getfile?00326606.pdf#search='delayed%20coincidence%20cadmium%20neutrino' suekane@FAPPS

  18. An episode At the same time of Reines& Cowan, R.Davis and L.Alvarez performed neutrino experiment at a Savannah river reactor, too. Their detection principle was, However, they failed to detect positive result. But this actually means the reactor neutrino (anti neutrino) dose not cause the reaction and neutrino and anti-neutrino are different particles (concept of that time) Later on, Davis also won Novel prize by detecting solar neutrinos with the same technique. Lessons : Negative result can be an important signature. : Hanging on is important for success. suekane@FAPPS

  19. Discovery of μ-neutrino * Neutrino Source: @ Brookhaven AGS π decays with 21m decay space. 99.99% of neutrinos are associated with muon production suekane@FAPPS

  20. Detection of neutrino * Target: 90 x 2.5cmt Al slab spark chambers Looked for m signal => a single track e signal => EM shower They observed 34 single track μ events 22 μ+X 6 backgrounds (not like e )  The neutrinos from b-decay and p decay are different particle suekane@FAPPS

  21. t neutrino (2000 DONUT group) * Production of t neutrino FNAL TEVATRON Then suekane@FAPPS

  22. Detection principle Look for the "kink" t decays after ct~87um, 85% for 1 prong mode 15% for 3 prongs mode. suekane@FAPPS

  23. the Detector Nuclear Emulsion (~thick camera film) position resolution <1mm suekane@FAPPS

  24. Results (2000) 3 prongs 1prong nt was observed in 1000 neutrino events. (9s significance) "We did R&D for t-neutrino detection around 1980 but once gave up because it seemed too difficult to success". K.Niwa suekane@FAPPS

  25. suekane@FAPPS

  26. Direct neutrino mass detection electron neutrino Principle Distortion of energy spectrum at the end point suekane@FAPPS

  27. Source: Tritium E0=small  good mn sensitivity Lifetime  reasonably short & long ideal isotope to seek for mν Z＝small  small correction * Strong Source * Large Acceptance * Energy measurement by Electric potential V detector Electric potential

  28. mne Results K. Eitel (Neutrino04) suekane@FAPPS

  29. K. Eitel (Neutrino04) From current to future experiments Mainz: Troitsk: mn2 = -1.2(-0.7)± 2.2 ± 2.1 eV2 mn2 = -2.3 ± 2.5 ± 2.0 eV2 mn < 2.2(2.3) eV (95%CL) mn < 2.1 eV (95%CL) C. Weinheimer, Nucl. Phys. B (Proc. Suppl.) 118 (2003) 279 V. Lobashev, private communication C. Kraus, EPS HEP2003 (neighbour excitations self-consistent) (allowing for a step function near endpoint) • aim: improvement of mn by one order of magnitude (2eV  0.2eV ) •  improvement of uncertainty on mn2 by 100 (4eV2  0.04eV2) • statistics: • stronger Tritium source (>>1010b´s/sec) • longer measurement (~100 days  ~1000 days) energy resolution: • DE/E=Bmin/Bmax  spectrometer with DE=1eV  Ø 10m UHV vessel suekane@FAPPS

  30. suekane@FAPPS

  31. suekane@FAPPS

  32. A famous picture suekane@FAPPS

  33. suekane@FAPPS

  34. K. Eitel (Neutrino04) KATRIN sensitivity & discovery potential expectation: after 3 full beam years ssyst~sstat mn = 0.35eV (5s) mn = 0.3eV (3s) 5s discovery potential mn < 0.2eV (90%CL) sensitivity suekane@FAPPS

  35. nm mass limit  suekane@FAPPS

  36. K.Assamagan et al. PRD53,6065(1996) A precise spectrometer @PSI suekane@FAPPS

  37. K.Assamagan et al. PRD53,6065(1996) energy loss in the target 0.1MeV/c pm (PDG average) suekane@FAPPS

  38. nm mass limit δmπ limits the precision suekane@FAPPS

  39. τ neutrino mass limit suekane@FAPPS

  40. distribution of mX & Ex,  obtain most likely mn Better precision for smaller Q-value, but low statistics, are used. PDG average； suekane@FAPPS

  41. nt nm Quark-Lepton masses n mass is very small Lower limit of heaviest neutrino mass is ~50meV n oscillation suekane@FAPPS

  42. Neutrinos in the Standard Model * Q=0, * No color * m=0, * s=1/2 * * onlynL exists (or nL may exist but it does not interact at all) W+ Z0 sin2qW~0.23 (Weinberg angle) suekane@FAPPS

  43. gw W+ Z0 Z0 W+ W- Flavor violation Lepton number violation Flavor violation suekane@FAPPS

  44. 'Helicity' Suppression of p-decay Experimental fact: How it is explained? You may say W couple only LH n and RH e. So that J(en)=1, while pion spin=0 => violates spin conservation W+ p+ However, this decay exists if very small. And for decay, the spin conservation seems to strongly violated. u p+ suekane@FAPPS

  45. Helicity and Chirality Sometimes Helicity and Chirality are used in confuse. Here they are defined and their relations are discussed. Dirac equation in free space is, General solution is, Now we take initial condition as positive energy and suekane@FAPPS

  46. Helicity is the spin component to the direction of the movement. If the movement is along the z-direction, helicity components are, These helicity states show actual spin direction. Here after we call Right(Left) handed Helicity =RH (LH) suekane@FAPPS

  47. What W couples to: Chirarity W couples to negative Chirality (NC) particle and positive Chirality (PC) state anti-particle. y- W Chirality components of yis defined by, y- For m 0, h1 and For high energy, the helicity and chirality are same and sometimes they are confused. For low energy, NC has RH component. suekane@FAPPS

  48. In p- e-n decay, e- is NC state and n is PC state. Then the The RH component of electron in the p decay is, So that the probability which is RH is, This means the electron has right handed component with probability This conserve spin p- For muon case, mm/Em~1 and the suppression is not strong. suekane@FAPPS

  49. Taking into account the phase space the theoretical prediction is 1.23x10-4 while observation is Likewise for K decay, while observation is  2.5x10-5 suekane@FAPPS

  50. f + e 0 Z If M=1, G=0.1 - e f G neutrino flavor counting using Z0 Mz=91GeV suekane@FAPPS

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