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Seeing the Sky Underground The Birth of Neutrino Astronomy

Seeing the Sky Underground The Birth of Neutrino Astronomy . Chiaki Yanagisawa. Stony Brook University. October 13, 2007 Custer Institute. History of Cosmic Rays/Neutrino Astronomy Researches. 1921 Hess discovered cosmic rays (CRs).

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Seeing the Sky Underground The Birth of Neutrino Astronomy

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  1. Seeing the Sky Underground The Birth of Neutrino Astronomy Chiaki Yanagisawa Stony Brook University October 13, 2007 Custer Institute

  2. History of Cosmic Rays/Neutrino Astronomy Researches 1921 Hess discovered cosmic rays (CRs) • Anderson found the first antimatter : Birth of elementary particle physics anti-electron (positron) 1937 Discovery of muon by Anderson 1949 Fermi’s theory of CR acceleration • Cosmic Microwave Background (CMB) Relic from Big Bang radiation discovered 1 eV: Energy acquired by an electron in 1 V First 1020 eV CR detected 1966 Proposal of GZK cutoff p + gCMB -> Np : Ecutoff=5x1019 eV Interaction of CR proton with CMB radiation 1019 eV 1020 eV

  3. History of Cosmic Rays/Neutrino Astronomy Researches 1967 Ray Davis detected first solar neutrinos Birth of neutrino astronomy CR Masatoshi Koshiba 1979 Masatoshi Koshiba got a new idea using water for proton decays 1981 Kamiokande started CR 1987 Neutrinos from Supernova SN1987A observed by Kamiokande/IMB Ray Davis 1991 Super-Kamiokande (SK) construction started Probably CRs hit their heads? Fly’s Eye detected 3x1020 eV CR 1994 AGASA detected 2x1020 eV CR 1996 SK started to take data 1998 Discovery of atmospheric neutrino oscillation by SK 2002 Confirmation of solar neutrino oscillation by SNO Nobel Prize to Davis,Koshiba,&Giacconi

  4. Particle Physics What is the world made of? nucleus Model of Atoms Old view proton electrons e- nucleus quarks Modern view Semi-modern view

  5. Particle Physics What is matter made of? Building Blocks of Matter Discoveries of too many “elementary” particles lead to more fundamental model the Standard Model. Proton p : uud Neutron n : udd - Pion p+ : ud Particles made of quarks are called hadrons

  6. Particle Physics How many kinds of forces are there? Fundamental Forces There are four know fundamental forces: An example: Free neutron decay

  7. Particle Physics Fundamental Forces An example of weak interaction - Free neutron decay: n p + e- + ne

  8. Particle Physics What is our dream? Unification of Forces Grand Unified Theories (GUTs) Strong Electric Electromagnetic 19th c. Magnetic Electroweak GUTs 21st c.? 20th c. Weak GUTs predict: Nucleon decays hard Neutrino mass/oscillation Gravitational

  9. Particle Physics What is neutrino oscillation? Neutrino Oscillation There are three kinds of neutrinos: ne nm nt (flavors) If neutrinos have mass, they can change their identities (flavors) ne nm nt A simple example: nm nt nm n1 - sin q n2 cos q = nt sin q n1 + cos q n2 = n1,2 neutrinos with definite mass Probability nm nm Probability It depends on neutrino energy, masses and q nm nt 1-Probability ~Earth’s diameter 12,000 km Neutrino pathlength (km)

  10. Atmospheric Neutrinos Source of atmospheric neutrinos Earth’s atmosphere is constantly bombarded by cosmic rays. Energetic cosmic rays (mostly protons) interact with atoms in the air. These interactions produce many particles-air showers. Neutrinos are produced in decays of pions and muons.

  11. Atmospheric Neutrinos to avoid most of cosmic rays Underground Experiments Ray Davis experiment detected the first solar neutrinos using Chlorine Cl at Homestake Kamiokande detected the first neutrinos from a supernova using water (3,000 tons).

  12. Atmospheric Neutrinos The successor of highly successful Kamiokande Super-Kamiokande: 50,000 tons of pure water equipped with 12,000 50 cm photomultipliers and 2,800 20 cm photomultipliers (PMTs). 40 m height 1,000 m deep 40 m diameter

  13. Physicists are having fun on a boat in Super-Kamiokande

  14. A physicist is checking installed photomultipliers

  15. Physicists are preparing photomultipliers: See how big they are!

  16. Atmospheric Neutrinos How does a water Cherenkov detector work? Water Cherenkov Detector: Kamiokande,IMB,Super-Kamiokande,SNO Water is cheap and easy to handle! When the speed of a charged particle exceeds that of light IN WATER, electric shock waves in form of light are generated similar to sonic boom sound by super-sonic jet plane . These light waves form a cone and are detected as a ring by a plane equipped by photo- sensors.

  17. Atmospheric Neutrinos How do we detect atmospheric muon and electron neutrinos ? muon-like ring Major interactions: ne + n -> p + e- nm + n -> p + m- Most of time invisible electron-like ring

  18. An event produced by an atmospheric muon neutrino

  19. Atmospheric Neutrinos How do we see neutrino oscillation in atmospheric neutrinos? a cos q = a/b q b Neutrino pathlength downward-going upward-going cos (zenith angle) Probability (nm->nm) Actual probability for measured zenith angle due to measurement errors

  20. Atmospheric Neutrinos Evidence of neutrino oscillation/mass with oscillation without oscillation low energy nm low energy ne high energy ne high energy nm First crack in the Standard Model!!!

  21. Solar Neutrinos How does the Sun shine? Nuclear fusions generate: - energy/heat/light - neutrinos Kamiokande 1 MeV = 1x106 eV

  22. Solar Neutrinos How do we detect solar neutrinos? Kamiokande,Super-Kamiokande: 3,000 tons , 50,000 tons Ray Davis Homestake Experiment: 615 tons - Detect the recoil electron which is kicked by a solar neutrino out of a water molecule. Counts the number of 37Ar using a chemical methods - Can measure the energy and direction of the recoil electron.

  23. Solar Neutrinos How do we see the Sun? Image of Sun by Super-Kamiokande Solar neutrinos background e e Seeing the Sun undergraound

  24. Solar Neutrinos Seeing the Earth’s Orbit Underground! Distance Earth-Sun Summer: 4 Jul. 156 million km Winter : 3 Jan. 146 million km Solar neutrino flux ~ (1/distance)2 Note: Flux less than half of expected (deficit)!!!

  25. Solar Neutrinos How do we see neutrino oscillation with solar neutrinos? Flux: measured/expected Homestake : 0.27+- 0.06 Neutrino deficit!!! Kamiokande : 0.44+- 0.06 Super-Kamiokande : 0.465+-0.005+0.016-0.015 nm is not visible to all experiments above

  26. Solar Neutrinos How can we prove it’s neutrino oscillation? Neutral current SNO experiment uses heavy water D2O instead of normal water H2O

  27. Solar Neutrinos How does the neutral current confirm neutrino oscillation? Neutral current interaction Elastic scattering -This reaction is flavour blind and is available for all kinds of neutrinos. -This reaction is available only for ne . -Available for both water and heavy water. - Available only for heavy water.

  28. Solar Neutrinos Confirmation of solar neutrino oscillation by SNO nm is visible only to SNO But not to Homestake, Kamiokande or Super- Kamiokande. Even if solar neutrino ne changes its flavour to nm or nt total flux of solar neutrino can be measured by SNO Solar flux measured: 6.4+-1.6 x 106 cm-2 s-1 Solar flux predicted : 5.1+-1.0 x 106 cm-2 s-1 Solar neutrinos oscillate!!!!

  29. Supernova

  30. Supernova

  31. Supernova SN 1987A, Feb.23, 1987 in Large Magellanic Cloud At about 170,000 light years away Before After 12 events 8 events Neutrinos from this SN were observed by Kamiokande and IMB 10 sec

  32. Supernova How do we know detected neutrinos are from a supernova? Birth of a supernova witnessed with neutrinos A few hours before optical observation Kamiokande Number of photomultipliers fired Taken by Hubble Telescope ( 1990) Background level

  33. Supernova Why is detection of supernova neutrinos important? We learn: • Properties of neutrinos: its mass (or limit of it), magnetic moment,electric • charge, etc. - Details of supernova explosion: how a star dies - How a neutron star or a black hole is formed if it happens

  34. Nobel Prize for Physics in 2002 The first detection of solar neutrinos by Ray Davis’s chlorineexperiment, and the subsequent confirmation by Kamiokande using real-time directional information and the first detection of supernova neutrinos opened up a new exciting field of neutrino astronomy. For these great achievements Ray Davis and Masatoshi Koshiba shared a Nobel Prize with Riccardo Giaconni who is the founding father of x-ray astronomy. Ray Davis Masatoshi Koshiba Riccardo Giocconi

  35. Nobel Prize for Physics in 2002 At Kamioka with Prof.Koshiba At Stony Brook with Dr.Davis

  36. What’s Next? Are all the mysteries solved? ANTARES • Where is all the missing • mass? • Are there any other neutrino • point sources? • Origin of ultra high energy • cosmic rays around and • beyond cutoff GZK cutoff Auger Project ?

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