1. 1962 Lederman,Schwartz,Steinberger Brookhaven National Laboratory using a   as a source of  antineutrinos and a 44-foot thick stack of steel (from a dismantled warship hull) to shield everything but the ’s found 29 instances of  + p   + + n but none of  + p  e + + n 1988 Nobel Prize in Physics "for the neutrino beam method and the demonstration of the doublet structure of the leptons through the discovery of the muon neutrino"

2. The Nuclear pp cycle producing energy in the sun 6 protons  4 He + 6  + 2 e + 2p 26.7 MeV Begins with the reaction 0.26 MeV neutrinos

3. 1967 built at Brookhaven labs 615 tons of tetrachloroethylene Neutrino interaction 37 Cl  37 Ar (radioactive isotope,  ½ = 35 days) Chemically extracting the 37 Ar, its radioactivity gives the number of neutrino interactions in the vat (thus the solar neutrino flux). ResultsResults: Collected data 1969-1993 (24 years!!) gives a mean of 2.5±0.2 SNU while theory predicts 8 SNU (1 SNU = 1 neutrino interaction per second for 10E+36 target atoms). This is a neutrino deficit of 69%. Homestake Mine Experiment

4. The energy spectrum of solar neutrinos predicted by the BP04 solar model. For continuum sources, the neutrino fluxes are given in number of neutrinos cm -2 s -1 MeV -1 at the Earth's surface. For line sources, the units are number of neutrinos cm -2 s -1. Total theoretical uncertainties are shown for each source. The difficult  to  detect CNO neutrino fluxes have been omitted in this plot. Solar models predict the spectrum and flux of solar neutrinos reaching the earth

5. The Solar Neutrino Problem The rate of detection of solar e ’s from is 3  smaller than expected!

6. Is the sun’s core cooler than we thought? 6% Is it a different age than we had assumed? New and extraordinarily precise measurements of “solar sound speeds” 1998 small oscillations in spectral line strengths studied by solar seismologists due to pressure waves traversing the solar volume confirm the predictions of internal temperature and pressure by standard solar models to with 0.1%

8. Atmospheric Neutrino Detection all showers start   e (all K s decaying rapidly into  s) with  s and Kaons  e     e  e e  e  →  +  Each pion decays by  → e + e +  and each muon decays by Note: at sea level N  N e = 2

9. One detector measures this significantly more accurately than any other SuperKamiokande They find R sub-GeV = 0.63  0.06 R multi-GeV = 0.65  0.09 Given the time dilation of muon lifetimes (and the probabilistic nature of their decays) we can still calculate/simulate the ratio we expect to observe at the ground, and compare:

10. The observed handedness of neutrinos is consistent with being massless p  but in a frame moving faster than the neutrino p  In quantum-field theoretical terms: overtaking a particle corresponds to the Lagrangian term: g =g=g =g=g =g=g =g=g g initial  R  final  L a Dirac mass term! † † †† † † †

11. We know the strong “mass” eigenstates of the quarks mix into the weak eigenstates. d c = dcos  + ssin  Do the lepton families also mix? What really distinguishes from ? Both appear massless, chargeless… Could ? Like the neutral kaons? Could ? Like the Cabibbo mixed quark families?

12. If e  state produced along with e in weak interactions   state produced along with  in weak interactions but these “weak-interaction” states e, ,  are actually super-positions (linear combinations) of the “mass” eigenstates 1, 2, 3 For a (simple) example of 2-d mixing Giving the states PRODUCED (initial state) by a weak decay while the propagation through space-time is quantum mechanically determined by

13. Since these components of the weakly produced states must initially be spacially coherent (have the same momentum) Then, using for m i << E i (but not zero) And writing observed weakly interacting state “mass” or vacuum states

14. If, for example, we started with  -type neutrinos at t = 0 then the probability of remaining a  : P ( ) = |   | 2 and if the | i  are orthogonal states P ( ) using e ix =cosx + isinx

15. P ( ) using along with the approximation P ( ) and finally with P ( ) and of course, then P ( ) 1  P ( ) =

16. The photon is massless and has no antiparticle (is its own antiparticle) But all the fundamental particles of matter do have antiparticles:  e + e  ee+ee+ ++ p pp p n nn n       The quark content of pions show while other mesons are their own antiparticle    

17. 1965 Gellmann & Pais noted a 2 nd order (~rare) weak interaction could induce the strangeness-violating transition of K o a particle becoming its own antiparticle! uu s d s d KoKo KoKo WW u u s d s d KoKo KoKo WW WW KK The neutral kaon however is not its own antiparticle: KK

18. u d ee e _ u u d d WW e+e+ e _ u d u d d u but have never observed: have observed: Cowan & Reines: Savannah River

19. In many even-even nuclei,  -decay is energetically forbidden. This leaves  -decay as the allowed decay mode. 76 As 33 76 Ge 32 76 Se 34 Endpoint Energy  22 0+ 2+ 0+ Atomic mass (u) 76 Ge 32 75.921402 76 As 33 75.922393 76 Se 34 75.919913 is observed!

20. If were its own antiparticle (or could oscillate into ) there could be a chance to observe neutrino-less double-beta decay events. the observed process being searched for! neutrino-less

21. Energy Spectrum for the double-beta decay Summed Energy for the 2 Electrons (MeV)

22. Neutrinoless double beta decay A single claimed observation has been made…but is very controversial ! It needs to be independently verified! Major US efforts –MAJORANA expt- 500 kg Ge76 (86%) –EXO - 1-ton LXe TPC Deeper site for later versions of GS experiments? –e.g, CUORE - 760 kg TeO2