J. Goodman – May 2003 Quarknet Symposium May 2003 Neutrinos, Dark Matter and the Cosmological Constant The Dark Side of the Universe Jordan Goodman University of Maryland

J. Goodman – May 2003 Outline Why do we care about neutrinos? Why do we think there is dark matter? Could some of it be neutrinos? The search for neutrino mass – Solar Neutrinos –Super-K –SNO –Kamland The accelerating Universe - Dark Energy –SCP –WMAP

J. Goodman – May 2003 Seeing Big Picture

J. Goodman – May 2003 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 – May 2003 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

J. Goodman – May 2003 Why do we think there is dark matter? Isn’t obvious that most of the matter in the Universe is in Stars? Spiral Galaxy

J. Goodman – May 2003 Why do we think there is dark matter? In a gravitationally bound system out past most of the mass V ~ 1/r 1/2 We can look at the rotation curves of other galaxies –They should drop off But they don’t!

J. Goodman – May 2003 Why do we think there is dark matter? There must be a large amount of unseen matter in the halo of galaxies –Maybe 20 times more than in the stars! –Our galaxy looks 30 kpc across but recent data shows that it looks like it’s 200 kpc across

J. Goodman – May 2003 Measuring the energy in the Universe We can measure the mass of clusters of galaxies with gravitational lensing These measurements give  mass ~0.3 We also know (from the primordial deuterium abundance) that only a small fraction is nucleons  nucleons < ~0.04 Gravitational lensing

J. Goodman – May 2003 Dark Matter

J. Goodman – May 2003 Dark Matter

J. Goodman – May 2003 What is this ghostly matter? Could it be neutrinos? How much neutrino mass would it take? –Proton mass is 938 MeV –Electron mass is 511 KeV –Neutrino mass of 2eV would solve the galaxy rotation problem – 20eV would close the Universe Theories say it can’t be all neutrinos –They have difficulty forming the kinds of structure observed. The structures they create are too large and form too late in the history of the universe

J. Goodman – May 2003 Does the neutrino have mass?

J. Goodman – May 2003 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 – May 2003 Neutrino Oscillations 1  2 =Electron Electron 1  2 =Muon Muon

J. Goodman – May 2003 Solar Neutrinos

J. Goodman – May 2003 Solar Neutrino Spectrum

J. Goodman – May 2003 Solar Neutrino Experiment History Homestake - Radiochemical –Huge tank of Cleaning Fluid ( perchloroethylene) 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 – May 2003 The Solar Neutrino Problem

J. Goodman – May 2003 The Solar Neutrino Problem

J. Goodman – May 2003 The Solar Neutrino Problem

J. Goodman – May 2003 Neutrino Oscillations

J. Goodman – May 2003 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 – May 2003 MSW Oscillations (Mikheev, Smirnov, Wolfenstein)

J. Goodman – May 2003 Oscillation Parameter Space LMA LOW VAC SMA

J. Goodman – May 2003 Solar Neutrinos in Super-K The ratio of NC/CC cross section is ~1/6.5

J. Goodman – May 2003 Super-Kamiokande

J. Goodman – May 2003 Super-Kamiokande

J. Goodman – May 2003 Super-K Huge tank of water shielded by a mountain in western Japan –50,000 tons of ultra clean water –11,200 20in diameter PMTs –Under 1.5km of rock to reduce downward cosmic rays (rate of muons drops from ~100k/sec to ~2/sec) 100 scientists from US and Japan Data taking began in 1996

J. Goodman – May 2003 Super-K site

J. Goodman – May 2003 Super-K site Mozumi

J. Goodman – May 2003 Solar Neutrinos in Super-K The ratio of NC/CC cross section is ~1/6.5

J. Goodman – May 2003 How do we see neutrinos? muon   electron e e-

J. Goodman – May 2003 Cherenkov Radiation Boat moves through water faster than wave speed. Bow wave (wake)

J. Goodman – May 2003 Cherenkov Radiation Faster than wave speed Slower than wave speed

J. Goodman – May 2003 Cherenkov Radiation Aircraft moves through air faster than speed of sound. Sonic boom

J. Goodman – May 2003 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 – May 2003 Cherenkov Radiation

J. Goodman – May 2003 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 – May 2003 A muon going through the detector

J. Goodman – May 2003 A muon going through the detector

J. Goodman – May 2003 A muon going through the detector

J. Goodman – May 2003 A muon going through the detector

J. Goodman – May 2003 A muon going through the detector

J. Goodman – May 2003 A muon going through the detector

J. Goodman – May 2003 Stopping Muon

J. Goodman – May 2003 Stopping Muon – Decay Electron

J. Goodman – May 2003 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 – May 2003 Solar Neutrinos

J. Goodman – May 2003 Energy Spectrum

J. Goodman – May 2003 Seasonal/Sunspot Variation

J. Goodman – May 2003 Energy Spectrum

J. Goodman – May 2003 Expected Day – Night Asymmetry Bahcall

J. Goodman – May 2003 Day / Night - BP2000+New 8 B Spectrum Preliminary

J. Goodman – May 2003 Day / Night Spectrum

J. Goodman – May 2003 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 – May 2003 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 – May 2003 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

J. Goodman – May 2003

(Like SK)

J. Goodman – May 2003 SNO CC Results

J. Goodman – May 2003 SNO CC Results CC Signal ES Signal SNO ES Signal Background Super-K

J. Goodman – May 2003 SNO CC Results  e = (35 ± 3 )%  ssm

J. Goodman – May 2003 Combining SK and SNO SNO measures  e = (35 ± 3 )%  ssm SK Measures  es = (47 ±.5 ± 1.6)%  ssm 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 – May 2003 SNO Results (NC)

J. Goodman – May 2003 SNO Results (NC/CC) SNO Results

J. Goodman – May 2003 SNO Results

J. Goodman – May 2003 SNO Day / Night

J. Goodman – May 2003 Combined SK and SNO Results

J. Goodman – May 2003 SK & SNO (with and w/o RadioChem) All data No Radio- Chem data

J. Goodman – May 2003 Kamland – Terrestrial Neutrinos

J. Goodman – May 2003 Reactors Contributing to Kamland

J. Goodman – May 2003 Kamland Results (Dec. 2002)

J. Goodman – May 2003 Kamland

J. Goodman – May 2003 Kamland

J. Goodman – May 2003 All Experiments Combined with Kamland

J. Goodman – May 2003 Smirnov Analysis

J. Goodman – May 2003 It looks like the Solar Neutrino problem has been solved! –All Data (except LSND) is now consistent with the large angle MSW solution – e ->  –We have ruled out SMA and Low solutions –Disfavor Sterile Neutrino solutions Neutrinos have mass! –This confirms the atmospheric neutrino results –The Solar  mass difference ~0.003eV Future Experiments – –MiniBoone – LSND effect Solar Neutrino Conclusions

J. Goodman – May 2003 Atmospheric Neutrino Production Ratio predicted to ~ 5% Absolute Flux Predicted to ~20% :

J. Goodman – May 2003 Atmospheric Oscillations about 13,000 km about 15 km Neutrinos produced in the atmosphere We look for transformations by looking at s with different distances from production SK

J. Goodman – May 2003 Atmospheric Neutrino Interactions Reaction Thresholds Electron: ~1.5 MeV Muon: ~110 MeV Tau: ~3500 MeV Charged Current Neutral Current e  e n p W +

J. Goodman – May 2003 Telling particles apart MuonElectron

J. Goodman – May 2003 Muon - Electron Identification PID Likelihood sub-GeV, Multi- GeV, 1-ring Monte Carlo (no oscillations) We expect about twice as many  as e

J. Goodman – May 2003 Super-K Atmospheric Data Set days of data (22.5 kilotons fiducial volume) Data Set is divided into: –Single and Multi Ring events –Electron-like and Muon-like –Energy Intervals 1.4 GeV Also E vis < 400MeV (little or no pointing) –Fully or partially contained muons (PC) –Upward going muons - stopping or through going Data is compared to Atmospheric Monte Carlo –Angle (path length through earth) –Visible energy of the Lepton

J. Goodman – May 2003 Low Energy Sample No Oscillations Oscillations (1.0, 2.4x10 -3 eV 2 )

J. Goodman – May 2003 Moderate Energy Sample

J. Goodman – May 2003 Multi-GeV Sample

J. Goodman – May 2003 Multi-Ring Events

J. Goodman – May 2003 Upward Going Muons

J. Goodman – May 2003 Summary of Atmospheric Results Best Fit for  to  Sin 2 2  =1.0,  M 2 =2.4 x eV 2  2 min =132.4/137 d.o.f. No Oscillations  2 min =316/135 d.o.f. 99% C.L. 90% C.L. 68% C.L. Best Fit Compelling evidence for  to  atmospheric neutrino oscillations Now the most cited exp. HEP paper Skip Tau studies

J. Goodman – May 2003 Tau Appearance? Tau’s require greater than 3 GeV in neutrino energy –This eliminates most events Three correlated methods were used –All look for enhanced upward going multi-ring events All show slight evidence for Tau appearance None are statistically significant

J. Goodman – May 2003 New Results

J. Goodman – May 2003 Neutrinos have mass Oscillations imply neutrinos have mass! We can estimate that neutrino mass is probably <0.2 eV – (we measure  M 2 ) Neutrinos can’t make up much of the dark matter – But they can be as massive as all the visible matter in the Universe! ~ ½ % of the closure density

J. Goodman – May 2003 Hubble Law

J. Goodman – May 2003 The expanding Universe The Universe is expanding Everything is moving away from everything Hubble’s law says the faster things are moving away the further they are away

J. Goodman – May 2003 The expanding Universe

J. Goodman – May 2003 Supernova Cosmology Project Set out to directly measure the deceleration of the Universe Measure distance vs brightness of a standard candle (type Ia Supernova) The Universe seems to be accelerating! Doesn’t fit Hubble Law (at 99% c.l.)

J. Goodman – May 2003 The expanding Universe

J. Goodman – May 2003 Energy Density in the Universe    may be made up of 2 parts a mass term and a “dark energy”  term (Cosmological Constant)    mass  energy Einstein invented  to keep the Universe static He later rejected it when he found out about Hubble expansion He called it his “biggest blunder”  m   

J. Goodman – May 2003 The Cosmological Constant

J. Goodman – May 2003 What is the “Shape” of Space? Closed Universe   >1 – C < 2  R Open Universe   <1 –Circumference (C) of a circle of radius R is C > 2  R Flat Universe   =1 – C = 2  R – Euclidean space

J. Goodman – May 2003 Results of SN Cosmology Project The Universe is accelerating The data require a positive value of  “Cosmological Constant” If    =1 then they find    ~ 0.7 ± 0.1

J. Goodman – May 2003 Accelerating Universe

J. Goodman – May 2003 Accelerating Universe

J. Goodman – May 2003 Measuring the energy in the Universe Studying the Cosmic Microwave radiation looks back at the radiation from 400,000 years after the “Big Bang”. This gives a measure of  0

J. Goodman – May 2003 Recent Results  0 =1  nucleon

J. Goodman – May 2003 WMAP -2003

J. Goodman – May 2003 WMAP

J. Goodman – May 2003 WMAP Results Universe is 13.7 billion years old with a margin of error of close to 1% Content of the Universe: 4% Atoms, 23% Cold Dark Matter, 73% Dark energy. Fast moving neutrinos do not play any major role in the evolution of structure in the universe. Expansion rate (Hubble constant) value: H o = 71 km/sec/Mpc (with a margin of error of about 5%) New evidence for Inflation (in polarized signal)

J. Goodman – May 2003 What does all the data say? Three pieces of data come together in one region    ~ 0.73  m ~ 0.27 (uncertainty  ~0.04) Universe is expanding & won’t collapse Only ~1/6 of the dark matter is ordinary matter (atoms) A previously unknown and unseen “dark energy” pervades all of space and is causing it to expand and accelerate

J. Goodman – May 2003 What do we know about “Dark Energy” It emits no light It acts like a large negative pressure P x ~ -  x It is approximately homogenous –At least it doesn’t cluster like matter Calculations of this pressure from first principles fail miserably – assuming it’s vacuum energy you predict a value of   ~ Bottom line – we know very little!

J. Goodman – May 2003 Conclusion  tota l = 1.02 ± 0.02 –The Universe is flat! The Universe is : ~1/2% Stars ~1/2% Neutrinos ~27% Dark Matter (only 4% is ordinary matter) ~73% Dark Energy We can see ~1/2% We can measure ~1/2% We can see the effect of ~27% (but don’t know what most of it is) And we are pretty much clueless about the other 3/4 of the Universe There is still a lot of Physics to learn!