J. Goodman – January 03 The Solution to the Solar Problem Jordan A. Goodman University of Maryland January 2003 Solar Neutrinos MSW Oscillations Super-K Results SNO Results Kamland Results Overall Results

J. Goodman – January 03 Our current view of underlying structure of matter P is uud N is udd   is ud k  is us and so on… The Standard Model } Baryons } Mesons (nucleons)

J. Goodman – January 03 Facts about Neutrinos Neutrinos are only weakly interacting 40 billion neutrinos continuously hit every cm 2 on earth from the Sun (24hrs/day) Interaction length is ~1 light-year of steel 1 out of 100 billion interact going through the Earth 1931 – Pauli predicts a neutral particle to explain energy and momentum non-conservation in Beta decay Enrico Fermi develops a comprehensive theory of radioactive decays, including Pauli's particle, Fermi calls it the neutrino (Italian: "little neutral one") Discovery of the neutrino is announced by Clyde Cowan and Fred Reines

J. Goodman – January 03 Why do we care about neutrinos? Neutrinos –They only interact weakly –If they have mass at all – it is very small They may be small, but there sure are a lot of them! –300 million per cubic meter left over from the Big Bang –with even a small mass they could be most of the mass in the Universe!

J. Goodman – January 03 Solar Neutrinos

J. Goodman – January 03 Solar Neutrino Spectrum

J. Goodman – January 03 Solar Neutrino Experiment History Homestake - Radiochemical –Huge tank of Cleaning Fluid – e + 37 Cl e Ar –Mostly 8 B neutrinos + some 7 Be –35 years at <0.5 ev/day –~1/3 SSM –(Davis Nobel Prize) Sage/Gallex - Radiochemical –“All” neutrinos – e + 71 Ga e Ge –4 years at ~0.75 ev /day –~2/3 SSM Kamiokande-II and -III – 8 B neutrinos only – e Elastic Scattering –10 years at 0.44 ev /day –~1/2 SSM –(Koshiba 2002 Nobel Prize)

J. Goodman – January 03 The Solar Neutrino Problem

J. Goodman – January 03 Disappearing Neutrinos? All of these experiments (except SNO) are sensitive mostly to e –The energies are too low to produce  or  so they can only see neutral current interactions from other flavors If neutrinos could transform from electron type to muon or tau type the data might be understood Neutrinos can only “oscillate” if they have different masses –This implies that they have mass! –This would have significant cosmological importance A neutrino mass of ~20ev would close the Universe –It would also imply violation of lepton flavor conservation

J. Goodman – January 03 Neutrino Oscillations

J. Goodman – January 03 Detecting Neutrino Mass If neutrinos of one type transform to another type they must have mass: The rate at which they oscillate will tell us the mass difference between the neutrinos and their mixing

J. Goodman – January 03 Neutrino Oscillations 1 2 =Electron Electron 1 2 =Muon Muon

J. Goodman – January 03 Neutrino Oscillations Could Neutrino Oscillations solve the solar neutrino problem? –Simple oscillations would require a cosmic conspiracy –The earth/sun distance would have to be just right to get rid of Be neutrinos Another solution was proposed – Resonant Matter Oscillations in the sun (MSW- Mikheev, Smirnov, Wolfenstein) Because electron neutrinos “feel” the effect of electrons in matter they acquire a larger effective mass –This is like an index of refraction

J. Goodman – January 03 MSW Oscillations (Mikheev, Smirnov, Wolfenstein)

J. Goodman – January 03 Oscillation Parameter Space LMA LOW VAC SMA

J. Goodman – January 03 Solar Neutrinos in Super-K The ratio of NC/CC cross section is ~1/6.5

J. Goodman – January 03 Cherenkov Radiation Boat moves through water faster than wave speed. Bow wave (wake)

J. Goodman – January 03 Cherenkov Radiation Aircraft moves through air faster than speed of sound. Sonic boom

J. Goodman – January 03 Cherenkov Radiation When a charged particle moves through transparent media faster than speed of light in that media. Cherenkov radiation Cone of light

J. Goodman – January 03 Super-K

J. Goodman – January 03 Super-Kamiokande

J. Goodman – January 03 Detecting neutrinos Electron or muon track Cherenkov ring on the wall The pattern tells us the energy and type of particle We can easily tell muons from electrons

J. Goodman – January 03 A muon going through the detector

J. Goodman – January 03 A muon going through the detector

J. Goodman – January 03 A muon going through the detector

J. Goodman – January 03 A muon going through the detector

J. Goodman – January 03 A muon going through the detector

J. Goodman – January 03 A muon going through the detector

J. Goodman – January 03 Stopping Muon

J. Goodman – January 03 Stopping Muon – Decay Electron

J. Goodman – January 03 Low Energy Electron in SK

J. Goodman – January 03 Solar Neutrinos in Super-K 1496 day sample (22.5 kiloton fiducial volume) Super-K measures: –The flux of 8 B solar neutrinos –Energy spectrum and direction of recoil electron Energy spectrum is flat from 0 to T max –The zenith angle distribution –Day / Night rates –Seasonal variations

J. Goodman – January 03 Solar Neutrinos

J. Goodman – January 03 Energy Spectrum

J. Goodman – January 03 Seasonal/Sunspot Variation

J. Goodman – January 03 Energy Spectrum

J. Goodman – January 03 Expected Day – Night Asymmetry Bahcall

J. Goodman – January 03 Day / Night - BP2000+New 8 B Spectrum Preliminary

J. Goodman – January 03 Day / Night Spectrum

J. Goodman – January 03 Combined Results e to  SK+Gallium+Cholrine - flux only allowed 95% C.L. 95% excluded by SK flux- independent zenith angle energy spectrum 95% C.L allowed. - SK flux constrained w/ zenith angle energy spectrum

J. Goodman – January 03 Combined Results e to  SK+Gallium+Cholrine - flux only allowed 95% C.L. 95% excluded by SK flux- independent zenith angle energy spectrum 95% C.L allowed. - SK flux constrained w/ zenith angle energy spectrum Enlarged View

J. Goodman – January 03 Combined Results e to sterile SK+Gallium+Cholrine - flux only allowed 95% C.L. 95% excluded by SK flux- independent zenith angle energy spectrum 95% C.L allowed. - SK flux constrained w/ zenith angle energy spectrum

(Like SK)

J. Goodman – January 03 SNO CC Results

J. Goodman – January 03 SNO CC Results CC Signal ES Signal SNO ES Signal Background Super-K

J. Goodman – January 03 SNO CC Results  e = (35 ± 3 )%  ssm

J. Goodman – January 03 Combining SK and SNO SNO measures  e = (35 ± 3 )%  ssm SK Measures  es = (47 ±.5 ± 1.6)%  ssm No Oscillation to active neutrinos: –~3  difference If Oscillation to active neutrinos: –SNO Measures just  e This implies that    ssm (~2/3 have oscillated) –SK measures  es =(  e + (    /6.5) Assuming osc. SNO predicts that SK will see  es ~ (35%+ 65%/6.5)  ssm = 45% ± 3%  ssm

J. Goodman – January 03 SNO Results (NC)

J. Goodman – January 03 SNO Results (NC/CC) SNO Results

J. Goodman – January 03 SNO Results

J. Goodman – January 03 SNO Day / Night

J. Goodman – January 03 Combined Results

J. Goodman – January 03 SK & SNO (with and w/o RadioChem) All data No Radio- Chem data

J. Goodman – January 03 Kamland – Terrestrial Neutrinos

J. Goodman – January 03 Reactors Contributing to Kamland

J. Goodman – January 03 Kamland Results (Dec. 2002)

J. Goodman – January 03 Kamland

J. Goodman – January 03 Kamland

J. Goodman – January 03 All Experiments Combined with Kamland

J. Goodman – January 03 Smirnov Analysis

J. Goodman – January 03 It looks like the Solar Neutrino problem has been solved! –All Data (except LSND) is now consistent with the large angle MSW solution –We have ruled out SMA and Low solutions –Disfavor Sterile Neutrino solutions Neutrinos have mass! –This confirms the atmospheric neutrino results –Neutrinos contribute approximately as much mass as all of the visible stars Future Experiments – –MiniBoone – LSND effect Solar Neutrino Conclusions