11/4/03Prof. Lynn Cominsky1 Class web site: Office: Darwin 329A and NASA E/PO (707) Best way to reach me: Astronomy 305/Frontiers in Astronomy

11/4/03Prof. Lynn Cominsky2 Group 10

11/4/03Prof. Lynn Cominsky3 Where are the Sun’s neutrinos? The Sun The Sun A bit of history A bit of history Properties Properties Regions Regions Sub-atomic Particles Sub-atomic Particles Solar neutrino problem Solar neutrino problem Neutrino oscillations Neutrino oscillations

11/4/03Prof. Lynn Cominsky4 The Solar Mass History of the changing views of the Sun’s place in the Universe History of the changing views of the Sun’s place in the Universe Written and produced by Lynda Williams for the SFSU Planetarium Written and produced by Lynda Williams for the SFSU Planetarium Play real movie

11/4/03Prof. Lynn Cominsky5 The Sun Song by the Chromatics Astrocapella video Astrocapella video

11/4/03Prof. Lynn Cominsky6 Solar Power The Sun is powered by nuclear fusion reactions in its core The Sun is powered by nuclear fusion reactions in its core The gravity from the Sun’s mass squeezes the nuclei together so that they can overcome electrostatic repulsion and fuse The gravity from the Sun’s mass squeezes the nuclei together so that they can overcome electrostatic repulsion and fuse … but high pressure and temperature encourage impact Electrostatic repulsion stops impact

11/4/03Prof. Lynn Cominsky7 Solar Power Hydrogen nuclei fuse to Deuterium and then Helium, releasing about 7 MeV each Hydrogen nuclei fuse to Deuterium and then Helium, releasing about 7 MeV each The released radiation keeps the Sun from collapsing due to its own gravity The released radiation keeps the Sun from collapsing due to its own gravity Start with 4 protons under enormous pressure and temperature End up with a “normal” helium nucleus, two gamma rays, two positrons and two neutrinos Several Reactions

11/4/03Prof. Lynn Cominsky8 Sun Facts Mass of Sun x kg Mass of Sun x kg Diameter of Sun 1,390,000 km Diameter of Sun 1,390,000 km Distance to Sun 1 A. U. or 93 x 10 6 miles or ~1.5 x m Distance to Sun 1 A. U. or 93 x 10 6 miles or ~1.5 x m Rotation Rate of Sun 25.4 d (equator) 36 d (poles) Rotation Rate of Sun 25.4 d (equator) 36 d (poles) Surface Temperature of Sun 5800 K (yellow visible light) Surface Temperature of Sun 5800 K (yellow visible light)

11/4/03Prof. Lynn Cominsky9 Sun Facts Power from Sun 3.86 x W Power from Sun 3.86 x W Composition of Sun 75% Hydrogen 25% Helium <0.1% other elements Composition of Sun 75% Hydrogen 25% Helium <0.1% other elements Age of Sun 4.5 billion years …. with another ~5 billion years to go Age of Sun 4.5 billion years …. with another ~5 billion years to go Pressure at core 2.50 x atm Pressure at core 2.50 x atm Magnetic Field of Sun a few Gauss (average) but up to G connecting sunspots of opposite polarity Magnetic Field of Sun a few Gauss (average) but up to G connecting sunspots of opposite polarity

11/4/03Prof. Lynn Cominsky10 Features of the Sun

11/4/03Prof. Lynn Cominsky11 Regions of the Sun Core – dense region consisting of plasma of electrons and protons which undergo nuclear fusion reactions to power the Sun. Temperature is greater than 15,000,000 K. Core – dense region consisting of plasma of electrons and protons which undergo nuclear fusion reactions to power the Sun. Temperature is greater than 15,000,000 K. Radiation zone – region containing both plasma and atoms. The atoms slowly (170,000 y) absorb and reradiate the energy created in the core, transporting it to the outer layers. Temperature is around 5,000,000 K. Radiation zone – region containing both plasma and atoms. The atoms slowly (170,000 y) absorb and reradiate the energy created in the core, transporting it to the outer layers. Temperature is around 5,000,000 K. Convection zone – turbulent region where the solar material “ boils ” to quickly (1 week) move heat to the outer layers. T ~ 2,000,000 K Convection zone – turbulent region where the solar material “ boils ” to quickly (1 week) move heat to the outer layers. T ~ 2,000,000 K

11/4/03Prof. Lynn Cominsky12 Regions of the Sun Photosphere – “ surface ” of the Sun that radiates visible light. Convection cells can be seen as granules – T ~ 5800 K Photosphere – “ surface ” of the Sun that radiates visible light. Convection cells can be seen as granules – T ~ 5800 K Sunspots – highly variable, dark, cool regions in the photosphere. T ~ 3500 K Sunspots – highly variable, dark, cool regions in the photosphere. T ~ 3500 K Chromosphere - thin (2000 km) layer outside photosphere in which Hydrogen absorbs radiation and reemits it as red light (H-alpha). Jagged outer edge has dancing “ flames ” or spicules. Chromosphere - thin (2000 km) layer outside photosphere in which Hydrogen absorbs radiation and reemits it as red light (H-alpha). Jagged outer edge has dancing “ flames ” or spicules.

11/4/03Prof. Lynn Cominsky13 Regions of the Sun Transition region – very thin (100 km) layer in which temperature rises from 20,000 to 10 6 K Transition region – very thin (100 km) layer in which temperature rises from 20,000 to 10 6 K Corona - very sparse outer ionized gas region with loops and streamers of magnetic field. Temperature ~ 10 6 K Corona - very sparse outer ionized gas region with loops and streamers of magnetic field. Temperature ~ 10 6 K Solar Movie shows: 1) Photosphere 2) Chromosphere 3) Corona

11/4/03Prof. Lynn Cominsky14 Solar Interior Sun has many oscillation modes Sun has many oscillation modes Helioseismology is used to study the interior of the Sun and to learn about the convection region Helioseismology is used to study the interior of the Sun and to learn about the convection region 3 SOHO instruments 3 SOHO instruments Computer simulation

11/4/03Prof. Lynn Cominsky15 Sunspot and Convection Cells Optical sunspot image from the Vacuum Tower telescope at the Sacramento Peak National Solar Observatory with100 km resolution Optical sunspot image from the Vacuum Tower telescope at the Sacramento Peak National Solar Observatory with100 km resolution Shows granules from convection - each is about 1000 km across and lasts for about 10 minutes Shows granules from convection - each is about 1000 km across and lasts for about 10 minutes

11/4/03Prof. Lynn Cominsky16 Solar Chromosphere Maps of the solar chromosphere are made by observing light in the H- alpha line Maps of the solar chromosphere are made by observing light in the H- alpha line Light is emitted in the H-alpha line when an electron jumps down from the n=3 shell to the n=2 shell in Hydrogen Light is emitted in the H-alpha line when an electron jumps down from the n=3 shell to the n=2 shell in Hydrogen

11/4/03Prof. Lynn Cominsky17 Solar Transition Region TRACE = Transition Region And Coronal Explorer TRACE = Transition Region And Coronal Explorer Blue = 360,000 K Blue = 360,000 K Green = 900,000 K Green = 900,000 K Red = 2,700,000 K Red = 2,700,000 K White = sum of all 3 White = sum of all 3 4/26/98

11/4/03Prof. Lynn Cominsky18 Solar Corona Only easily visible during solar eclipse Only easily visible during solar eclipse Eclipses can be created artificially in coronographs Eclipses can be created artificially in coronographs SOHO/LASCO movie

11/4/03Prof. Lynn Cominsky19 Sun in X-rays X-rays from corona, prominences, flares and sunspots X-rays from corona, prominences, flares and sunspots Yohkoh movie

11/4/03Prof. Lynn Cominsky20 Sub- Atomic Particles Atoms are made of protons, neutrons and electrons Atoms are made of protons, neutrons and electrons % % of the atom is empty space of the atom is empty space Electrons have locations described by probability functions Electrons have locations described by probability functions Nuclei have protons and neutrons Nuclei have protons and neutrons nucleus m p = 1836 m e

11/4/03Prof. Lynn Cominsky21 Leptons An electron is the most common example of a lepton – particles which appear pointlike An electron is the most common example of a lepton – particles which appear pointlike Neutrinos are also leptons Neutrinos are also leptons There are 3 generations of leptons, each has a massive particle and an associated neutrino There are 3 generations of leptons, each has a massive particle and an associated neutrino Each lepton also has an anti-lepton (for example the electron and positron) Each lepton also has an anti-lepton (for example the electron and positron) Heavier leptons decay into lighter leptons plus neutrinos (but lepton number must be conserved in these decays) Heavier leptons decay into lighter leptons plus neutrinos (but lepton number must be conserved in these decays)

11/4/03Prof. Lynn Cominsky22 Types of Leptons LeptonCharge Mass (GeV/c 2 ) Electron neutrino 00 Electron Muon neutrino 00 Muon0.106 Tau neutrino 00 Tau175

11/4/03Prof. Lynn Cominsky23 Atomic Forces Electrons are bound to nucleus by Coulomb (electromagnetic) force Electrons are bound to nucleus by Coulomb (electromagnetic) force Protons in nucleus are held together by residual strong nuclear force Protons in nucleus are held together by residual strong nuclear force Neutrons can beta-decay into protons by weak nuclear force, emitting an electron and an anti-neutrino Neutrons can beta-decay into protons by weak nuclear force, emitting an electron and an anti-neutrino F = k q 1 q 2 r 2 n = p + e +

11/4/03Prof. Lynn Cominsky24 Neutrinos in the Standard Model The “standard model” of particle physics seeks to explain all the particles and forces that are observed The “standard model” of particle physics seeks to explain all the particles and forces that are observed In this model, there are 3 flavors of neutrinos: electron, muon and tau In this model, there are 3 flavors of neutrinos: electron, muon and tau All three types of neutrinos are massless and travel at lightspeed All three types of neutrinos are massless and travel at lightspeed If neutrinos have mass, their mass could affect how the structure in the universe is formed If neutrinos have mass, their mass could affect how the structure in the universe is formed

11/4/03Prof. Lynn Cominsky25 Solar neutrino problem history First experiments (1969) that detected solar neutrinos found about half the rate expected from models of nuclear reactions in the Sun First experiments (1969) that detected solar neutrinos found about half the rate expected from models of nuclear reactions in the Sun The neutrinos predicted from the models (and detected in the experiments) are all electron neutrinos – so either: The neutrinos predicted from the models (and detected in the experiments) are all electron neutrinos – so either: the models were wrong the models were wrong something happened to the neutrinos on their way to the Earth something happened to the neutrinos on their way to the Earth Many experiments in 1980s-1990s showed the perhaps the neutrinos were changing flavors (from electron neutrinos to some other type) Many experiments in 1980s-1990s showed the perhaps the neutrinos were changing flavors (from electron neutrinos to some other type)

11/4/03Prof. Lynn Cominsky26 Solar neutrino problem 4p  4 He + 2e e + 25 MeV 4p  4 He + 2e e + 25 MeV Chlorine atoms can capture neutrinos Chlorine atoms can capture neutrinos

11/4/03Prof. Lynn Cominsky27 Homestake mine neutrino experiment In an old mine in South Dakota (1967 – 1984) In an old mine in South Dakota (1967 – 1984) 20 feet in diameter 20 feet in diameter 48 feet long, 48 feet long, held 100,000 gallons of tetrachloroethylene held 100,000 gallons of tetrachloroethylene located 4,900 feet below ground surface. located 4,900 feet below ground surface. Courtesy of Brookhaven National Laboratory

11/4/03Prof. Lynn Cominsky28 Homestake mine neutrino experiment Ray Davis Jr. takes a dip in the 300,000 gallons of water that surrounds the perchloroethylene tank Ray Davis Jr. takes a dip in the 300,000 gallons of water that surrounds the perchloroethylene tank Water lowers background rates Water lowers background rates Detects electron neutrinos only Detects electron neutrinos only Photo courtesy of Brookhaven National Laboratory

11/4/03Prof. Lynn Cominsky29 Sun in Neutrinos Super Kamiokande neutrino observatory Super Kamiokande neutrino observatory 500 day image 500 day image 90 x 90 degrees centered on Sun 90 x 90 degrees centered on Sun

11/4/03Prof. Lynn Cominsky30 SuperKamiokande CAN DETECT ALL 3 TYPES OF NEUTRINOS CAN DETECT ALL 3 TYPES OF NEUTRINOS Water Cerenkov Detector Water Cerenkov Detector 41.4m (Height) x 39.3m (Diameter) 41.4m (Height) x 39.3m (Diameter) 50,000 tons of pure water 50,000 tons of pure water 1,000m underground 1,000m underground 11,200 photomultiplier tubes 11,200 photomultiplier tubes SuperK detector

11/4/03Prof. Lynn Cominsky31 Where solar neutrinos come from

11/4/03Prof. Lynn Cominsky32 Neutrino Oscillations A pion decays in the upper atmosphere to a muon and a muon neutrino A pion decays in the upper atmosphere to a muon and a muon neutrino Neutrinos oscillate flavors between muon and tau Neutrinos oscillate flavors between muon and tau

11/4/03Prof. Lynn Cominsky33 Neutrino Oscillations High energy neutrinos that travel a short distance do not change their flavor High energy neutrinos that travel a short distance do not change their flavor Low energy neutrinos that travel a long distance have a 50% chance of changing flavors Low energy neutrinos that travel a long distance have a 50% chance of changing flavors  (m 2 c 4 ) = eV 2

11/4/03Prof. Lynn Cominsky34 Neutrino Oscillations/KEK K2K (KEK to SuperK) is the new experiment testing neutrino oscillation results K2K (KEK to SuperK) is the new experiment testing neutrino oscillation results Neutrinos produced at KEK are measured at near detector and then shot 250 km across Japan to SuperK detectors Neutrinos produced at KEK are measured at near detector and then shot 250 km across Japan to SuperK detectors First events were detected in 1999 – confirm oscillations (56 seen, 80 expected by 2001) First events were detected in 1999 – confirm oscillations (56 seen, 80 expected by 2001)

11/4/03Prof. Lynn Cominsky35 SuperKamiokande Severely damaged in accident on 11/12/01 – over 5000 phototubes were destroyed Severely damaged in accident on 11/12/01 – over 5000 phototubes were destroyed Is being rebuilt – online again by 2003 Is being rebuilt – online again by 2003 First priority – resume K2K experiment by 2003 half of previous phototubes First priority – resume K2K experiment by 2003 half of previous phototubes Bottom of SuperK detector covered with broken PMTs after accident

11/4/03Prof. Lynn Cominsky36 Sudbury Neutrino Observatory >2000 meters below ground, in active mine >2000 meters below ground, in active mine Spherical detector, 12 m in diameter, filled with 1000 tons of heavy water, surrounded by 30 m cavity filled with normal water Spherical detector, 12 m in diameter, filled with 1000 tons of heavy water, surrounded by 30 m cavity filled with normal water 10,000 photomultipliers measure light flashes when heavy water catches neutrinos (e-) 10,000 photomultipliers measure light flashes when heavy water catches neutrinos (e-)

11/4/03Prof. Lynn Cominsky37 Comparing SuperK and SNO SuperK detects all 3 types of neutrinos vs. SNO which detects e- neutrinos only SuperK detects all 3 types of neutrinos vs. SNO which detects e- neutrinos only The numbers do not agree! The numbers do not agree! Use joint data set to predict total numbers of neutrinos reaching Earth Use joint data set to predict total numbers of neutrinos reaching Earth Prediction now agrees with solar models Prediction now agrees with solar models  Neutrino oscillations now confirmed!  Neutrino oscillations now confirmed!  Neutrinos have some mass!!  Neutrinos have some mass!!  Particle physics models must change  Particle physics models must change

11/4/03Prof. Lynn Cominsky38 Nobel Prize in Physics 2002 “for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos” “for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos” Raymond Davis Jr. & Masatoshi Koshiba Raymond Davis Jr. & Masatoshi Koshiba

11/4/03Prof. Lynn Cominsky39 Nobel Prize in Physics 2002 Raymond Davis Jr constructed a completely new detector, a gigantic tank filled with 600 tons of fluid, which was placed in a mine. Over a period of 30 years he succeeded in capturing a total of 2,000 neutrinos from the Sun and was thus able to prove that fusion provided the energy from the Sun. Raymond Davis Jr constructed a completely new detector, a gigantic tank filled with 600 tons of fluid, which was placed in a mine. Over a period of 30 years he succeeded in capturing a total of 2,000 neutrinos from the Sun and was thus able to prove that fusion provided the energy from the Sun. With another gigantic detector, called Kamiokande, a group of researchers led by Masatoshi Koshiba was able to confirm Davis’s results. They were also able, on 23 February 1987, to detect neutrinos from a distant supernova explosion. They captured twelve of the total of neutrinos (10,000,000,000,000,000) that passed through the detector. With another gigantic detector, called Kamiokande, a group of researchers led by Masatoshi Koshiba was able to confirm Davis’s results. They were also able, on 23 February 1987, to detect neutrinos from a distant supernova explosion. They captured twelve of the total of neutrinos (10,000,000,000,000,000) that passed through the detector. The work of Davis and Koshiba has led to unexpected discoveries and a new, intensive field of research, neutrino-astronomy. The work of Davis and Koshiba has led to unexpected discoveries and a new, intensive field of research, neutrino-astronomy.

11/4/03Prof. Lynn Cominsky40 AMANDA Antarctic Muon And Neutrino Detector Array Antarctic Muon And Neutrino Detector Array Purpose: high-energy (~ 1 TeV or electron volt) neutrinos from astrophysical point sources. Purpose: high-energy (~ 1 TeV or electron volt) neutrinos from astrophysical point sources. 302 PMTs on 10 strings at depths of meters 302 PMTs on 10 strings at depths of meters Videotape of lecture about AMANDA Videotape of lecture about AMANDA

11/4/03Prof. Lynn Cominsky41 Web Resources Astro Capella Sun song Astro Capella Sun song Sun Structure Sun Structure Clear Skies Clear Skies The Particle Adventure Nobel Prizes Ray Davis photos Ray Davis photos

11/4/03Prof. Lynn Cominsky42 Web Resources Sudbury Neutrino Observatory Sudbury Neutrino Observatory John Bahcall’s neutrino pages John Bahcall’s neutrino pages Homestake Neutrino Laboratory htm Homestake Neutrino Laboratory htm htm htm Super Kamiokande Super Kamiokandehttp://www-sk.icrr.u-tokyo.ac.jp/doc/sk/