DOCSLIB.ORG

Neutrino Astronomy LY NN HEYDASCH STEFAN BERNEGGER UZH FS 2017 / AST 202 – 11

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Neutrino Astronomy LY NN HEYDASCH STEFAN BERNEGGER UZH FS 2017 / AST 202 – 11. APRIL 2017 Neutrino astronomy Goal: Understand the basics of neutrino astronomy. Definition: “Branch of astronomy dealing with the detection and measurement of neutrinos emitted by the sun and other celestial objects.” Table of contents: 1. What are neutrinos? 2. What are the sources of neutrinos? 3. How to detect neutrinos? 4. What are neutrinos telling us? Q&A Rest mass of elementary particles Tauon Charm quark Charm Top quark Electron Bottom quarkBottom Down quarkDown Strange quark Strange Upquark Neutrinos ? Muon 1 meV 1 eV 1 keV 1 MeV 1 GeV 1 TeV 1. WHat are neutrinos? LOW MASS, NEUTRAL ELEMENTARY PARTICLES, PROPAGATING VERY CLOSE TO THE SPEED OF LIGHT, QUITE DISTINCT FROM THEIR COUNTERPARTS. Neutrinos • Elementary particle(s) • Electrically neutral • Three generations (flavors) of neutrinos: Standard model of particle physics • ��, ��, �� (and ��, ��, ��) • Partners of e, μ and τ • Interacting via the weak force (Z, W) only (and gravity) • Very low (≤0.12eV/c2) but non zero rest mass Solar neutrino problem • 1960’s Homestake experiment: Number of measured solar ��-neutrinos only 30%-50% of expected • No errors found in solar models and experimental setup • Hypothesis: Neutrinos have small mass and can oscillate • 2001 Sudbury Neutrino Observatory experiment: 35% ��, 65% �� and �� Neutrino astronomy vs photon astronomy NEUTRINO ASTRONOMY PHOTON ASTRONOMY • Interaction partner • e-, p+, n • e-, p+ • Flux from the sun • 6.5 ∙1010/sec/cm2 • 3.5 ∙1017 /sec/cm2 • Processes between source • Neutrino oscillations, red shift • Interaction with matter, red and detector shift • About 1 in 1036 • Detection rate • Close to 100% 5 20 • Energy range • ?... 10 eV up to 10 eV … ? • 10-4 eV to 1014 eV • Energy resolution • 0.2 (log energy) • 1/100’000 • Viewing angle [sr] • 4π • 10-8 to 10-4 • Spatial resolution • 1° to 10° (IceCube) • 0.01 arc sec (e.g. E-ELT) 2. Sources of neutrinos? BIG BANG, EXTRA-GALACTIC, GALACTIC, SOLAR AND TERRESTRIAL � –PROCESSES. Sources of neutrinos • Extraterrestrial sources: • LS/S: Low-energy-/Solar neutrinos → �� • LSN/SN: Low-energy-/Supernova Neutrinos, e.g. SN 1987A → 24 neutrinos within 13s • GRB: Gamma Ray Burst neutrinos • CR: Cosmic Ray neutrinos • PUL: PULsar neutrino • AGN: Active Galactic Nuclei neutrinos • CNB (CνB): Cosmic Neutrino Background (Big Bang) • ATM: ATMospheric neutrinos: cosmic rays • Terrestrial sources • Man made sources 3. How to detect neutrinos? ANY � –PROCESS CAN - IN PRINCIPLE - BE USED, BUT A LARGE AMOUNT OF MASS IS NEEDED. ASTRONOMY: WATER/ICE IS THE ONLY CHOICE! Detection via neutrino capturing and scattering • Neutrino astronomy: • Low neutrino flux: • Need for very massive detectors • Solution: Large water or ice body (order of km3) • Čerenkov detector: • 3D array of Digital Optical Modules (DOM’s) • Largest neutrino telescopes: • IceCube: South Pole, 1 km3 ice, 5’160 DOM’s • ANTARES/KM3NeT: Mediterranean, 5 km3 water, 10’800 DOM’s • Multiple neutrino reaction channels • Particle showers created by high energy neutrinos Neutrino interactions (Source: Thesis Erwin Visser) Example: IceCube 4. What are neutrinos telling us? NEUTRINO ASTRONOMY IS COMPLEMENTARY TO PHOTON ASTRONOMY. IT CAN PROVIDE A DEEP INSIGHT INTO OTHERWISE OBSCURED PROCESSES. Topics to be (potentially) addressed by neutrino astronomy • Properties of high energy particles absorbed by the atmosphere • Validation of solar nuclear reaction model • Validation of supernova models • Understanding of galactic high energy processes and view into the galactic center • Big Bang footprint • Test of cosmological models (dark matter, dark energy) Solar fusion process • Several β-processes as per Standard Solar Model: • Most relevant: pp reaction • Real-time monitoring of the nuclear fusion processes • Measuring the neutrino flux is the foundation for model validation Solar neutrinos (proton-proton chain) in the Standard Solar Model. Remark: Lepton conservation requires an even number of leptons to be involved in each reaction. Supernova + − 0 • Proton-electron recombination: � + � ⟶ � + �� • A huge number of high energy neutrinos is emitted within 10 sec • Neutrino signal is emitted some hours ahead of the electromagnetic signal • Network of neutrino detectors can be used as a SN alert system 11 • Dissipation of thermal energy (10 K): γ ⟶ �� + �� • Neutrinos carry away most of the gravitational energy (2∙1046 J) Big Bang • Nucleosynthesis and cosmological models: • Decoupling of neutrinos from matter 1s after BB (380’000yrs for photons) • Cosmic neutrino background: CNB or CνB (CMB for photons) • Estimated as-if temperature: Tν = 1.95K vs Tγ = 2.75K (CMB) • Direct detection most difficult but not impossible • Compelling indirect evidence: • Number of neutrino species is encoded in CMB • Standard Model perfectly consistent with empirical data Q&A References • https://en.wikipedia.org/wiki/Neutrino • https://icecube.wisc.edu/ • https://icecube.wisc.edu/icecube/static/reports/IceCubeReview2010.pdf • http://www.astro.caltech.edu/~golwala/ph135c/16WilburNeutrinoAstronomy.pdf • https://www.nikhef.nl/pub/services/biblio/theses_pdf/thesis_EL_Visser.pdf • https://www.nasa.gov/topics/universe/features/wmap_five.html • https://www.nasa.gov/centers/marshall/news/news/releases/2014/14-169.html • https://www.bnl.gov/science/neutrinos.php Appendix Neutrinos • Postulated in 1930 by Wolfgang Pauli (conservation laws in β-decay) • Detected in 1956 by Clyde Cowan and Frederick Reines The first use of a hydrogen bubble chamber to detect neutrinos, on November 13, 1970. A neutrino hit a proton in a hydrogen atom. Image: Argonne National Laboratory. Neutrino oscillations • Neutrino oscillations: • Each flavor eigenstate is a superposition of 3 mass eigenstates • Dispersion of mass eigenstates when propagating inside dense bodies (e.g. Sun or Earth): • The phase velocity is mass-dependent and varies for the three mass eigenstates, leading to respective phase shifts • The neutrino is no longer a flavor eigenstate by the time it leaves the sun • Solar neutrinos reaching Earth can be represented as a superposition of flavor eigenstates • Quantum Mechanics: The detection likelihood for each flavor depends on the respective amplitude Sources of neutrinos • Extraterrestrial sources • Terrestrial sources: • T: Terrestrial/geologic neutrinos (β-decay) → �� • ATM: ATMospheric neutrinos (cosmic rays) → ��, �� • Man made sources: • R: Reactor neutrinos (fission and fusion) • AN: Accelerator neutrinos (e.g. CERN) • Nuclear bombs (fission and fusion ) Detection via neutrino capturing • Many isotopes are decaying via a β– process: • A neutrino is emitted together with the electron or positron • Any β–process can in principle also be used for the detection of neutrinos • Very low reaction rate: Only a few approaches are technically feasible Weak reactions • Nuclear reactions can be transformed (Feynman): • Example: emission vs capturing process: • Neutrino emission: �0 ⟶ �+ + �− + � + � − 0 � + � ⟶ � + �� • Neutrino capturing: � + �+ ⟶ �0 + �+ � 0 + − �� + � ⟶ � + � • Preservation of lepton-number • Any β-decay process can in principle be used for detection • The cross section (reaction rate) for neutrino capturing is very low • The energy range covered by a detector depends on the isotope used • Multiple reaction channels: • ES: Elastic Scattering • NC: Neutral Current (Z-boson) • CC: Charged Current (W-boson) • BB: Double β-decay ? Big Bang • Very low energy and direct detection most difficult, but not impossible: • The tiny �− energy difference allows in principle to discriminate between (PTOLEMY experiment): 3 3 − • capturing of CνB neutrinos: � + 1� ⟶ 2�� + � 3 3 − • natural beta decay of tritium: 1� ⟶ 2�� + � + � • Compelling indirect evidence: • Interaction of ν with matter and photons permits to derive Nν (= 3 neutrino species + correction term): • Standard Model: Nν = 3.046 • Planck (CMB): Nν = 3.15 ± 0.23.
Recommended publications
  • Catholic Christian Christian

    Catholic Christian Christian

    Religious Scientists (From the Vatican Observatory Website) https://www.vofoundation.org/faith-and-science/religious-scientists/ Many scientists are religious people—men and women of faith—believers in God. This section features some of the religious scientists who appear in different entries on these Faith and Science pages. Some of these scientists are well-known, others less so. Many are Catholic, many are not. Most are Christian, but some are not. Some of these scientists of faith have lived saintly lives. Many scientists who are faith-full tend to describe science as an effort to understand the works of God and thus to grow closer to God. Quite a few describe their work in science almost as a duty they have to seek to improve the lives of their fellow human beings through greater understanding of the world around them. But the people featured here are featured because they are scientists, not because they are saints (even when they are, in fact, saints). Scientists tend to be creative, independent-minded and confident of their ideas. We also maintain a longer listing of scientists of faith who may or may not be discussed on these Faith and Science pages—click here for that listing. Agnesi, Maria Gaetana (1718-1799) Catholic Christian A child prodigy who obtained education and acclaim for her abilities in math and physics, as well as support from Pope Benedict XIV, Agnesi would write an early calculus textbook. She later abandoned her work in mathematics and physics and chose a life of service to those in need. Click here for Vatican Observatory Faith and Science entries about Maria Gaetana Agnesi.
  • Neutrino Astronomy

    Neutrino Astronomy

    Astrophysics from Antarctica Proceedings IAU Symposium No. 288, 2012 c International Astronomical Union 2013 M. G. Burton, X. Cui & N. F. H. Tothill, eds. doi:10.1017/S1743921312016729 Neutrino Astronomy: An Update Francis Halzen Department of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin-Madison email: [email protected] Abstract. Detecting neutrinos associated with the still enigmatic sources of cosmic rays has reached a new watershed with the completion of IceCube, the first detector with sensitivity to the anticipated fluxes. In this review, we will briefly revisit the rationale for constructing kilometer-scale neutrino detectors and summarize the status of the field. Keywords. Neutrinos, cosmic rays, astrophysics 1. Introduction Soon after the 1956 observation of the neutrino (Reines, 1956), the idea emerged that it represented the ideal astronomical messenger. Neutrinos reach us from the edge of the Universe without absorption and with no deflection by magnetic fields. Neutrinos have the potential to escape unscathed from the inner neighborhood of black holes, and, the subject of this update, from the cosmic accelerators where cosmic rays are born. Their weak interactions also make cosmic neutrinos very difficult to detect. Immense parti- cle detectors are required to collect cosmic neutrinos in statistically significant numbers (Klein, 2008). Already by the 1970s, it had been understood that a kilometer-scale de- tector was needed to observe the “cosmogenic” neutrinos produced in the interactions of cosmic rays with background microwave photons (Roberts, 1992). Today’s estimates of the sensitivity for observing potential cosmic accelerators such as Galactic supernova remnants, active galactic nuclei (AGN), and gamma-ray bursts (GRB) unfortunately point to the same exigent requirement (Gaisser, 1995).
  • Melvin Schwartz 1932-2006

    Melvin Schwartz 1932-2006

    MELVIN SCHWARTZ 1932-2006 A Biographical Memoir by N. P. SAMIOS AND P. YAMIN © 2012 The National Academy of Sciences Any opinions expressed in this memoir are those of the authors and do not necessarily reflect the views of the National Academy of Sciences. MELVIN SCHWARTZ Courtesy of Brookhaven National Laboratories. November 2, 1932–August 28, 2006 BY N. P. SAMIOS AND P. YAMIN MEL SCHWARTZ DIED ON August 28, 2006, in Twin Falls, Idaho. He was born on 1 November 2, 1932, in New York City. He grew up in the Great Depression, but with a sense of optimism and desire to use his mind for the betterment of human- kind. He entered the Bronx High School of Science in the fall of 1945. It was there that his interest in physics began and that he recognized the importance of interactions with peers in determining his sense of direction in life. One of his classmates and future colleagues recalled that “even then” he wanted a Nobel Prize. Mel noted: My interest in physics began at the age of 12 when I entered the Bronx High School of Science. The four years I spent there were certainly among the most exciting and stimulating in my life, mostly because of the interaction with the other students of similar background, interest, and ability. MELVIN SCHWARTZ MELVIN On Sunday afternoons he attended a school run by the secular and Zionist Yiddish and many others. As Mel commented, “This faculty [was] at this time unmatched by any in the world, largely Nationaler Arbeter Farband (Jewish National Workers Alliance).
  • Session: Neutrino Astronomy

    Session: Neutrino Astronomy

    Session: Neutrino Astronomy Chair: Takaaki Kajita, Institute for Cosmic Ray Research, Univ. of Tokyo Basic natures of neutrinos Neutrino was introduced in 1930 by W. Pauli in order to save the energy conservation law in nuclear beta decay processes, in which the emitted electron exhibits a continuous energy spectrum. It was assumed that the penetration power of neutrinos is much higher than that of the gamma rays. More than 20 years later, the existence of neutrinos was experimentally confirmed by an experiment that measured neutrinos produced by a nuclear power reactor. Since then, the basic nature of neutrinos has been understood through various theoretical and experimental studies: Neutrinos interact with matter extremely weakly. The number of neutrino species is three. They are called electron-neutrino, muon-neutrino and tau-neutrino. In addition, recent neutrino experiments discovered that neutrinos have very small masses. Observing the Universe by neutrinos (1) Because of the extremely high penetration power of neutrinos, neutrinos produced at the center of a star easily penetrate to the outer space. Theories of astrophysics predict that there are various processes that neutrinos play an essential role at the center of stars. For example, the Sun is generating its energy by nuclear fusion processes in the central region. In these processes, low energy electron neutrinos with various energy spectra are generated. Thus the observation of solar neutrinos directly probes the nuclear fusion reactions in the Sun. Another example is the supernova explosion. While the optical measurements observe an exploding star, what is happening in the central region of the star is the collapse of the core of a massive star.
  • 01Ii Beam Line

    01Ii Beam Line

    STA N FO RD LIN EA R A C C ELERA TO R C EN TER Fall 2001, Vol. 31, No. 3 CONTENTS A PERIODICAL OF PARTICLE PHYSICS FALL 2001 VOL. 31, NUMBER 3 Guest Editor MICHAEL RIORDAN Editors RENE DONALDSON, BILL KIRK Contributing Editors GORDON FRASER JUDY JACKSON, AKIHIRO MAKI MICHAEL RIORDAN, PEDRO WALOSCHEK Editorial Advisory Board PATRICIA BURCHAT, DAVID BURKE LANCE DIXON, EDWARD HARTOUNI ABRAHAM SEIDEN, GEORGE SMOOT HERMAN WINICK Illustrations TERRY ANDERSON Distribution CRYSTAL TILGHMAN The Beam Line is published quarterly by the Stanford Linear Accelerator Center, Box 4349, Stanford, CA 94309. Telephone: (650) 926-2585. EMAIL: [email protected] FAX: (650) 926-4500 Issues of the Beam Line are accessible electroni- cally on the World Wide Web at http://www.slac. stanford.edu/pubs/beamline. SLAC is operated by Stanford University under contract with the U.S. Department of Energy. The opinions of the authors do not necessarily reflect the policies of the Stanford Linear Accelerator Center. Cover: The Sudbury Neutrino Observatory detects neutrinos from the sun. This interior view from beneath the detector shows the acrylic vessel containing 1000 tons of heavy water, surrounded by photomultiplier tubes. (Courtesy SNO Collaboration) Printed on recycled paper 2 FOREWORD 32 THE ENIGMATIC WORLD David O. Caldwell OF NEUTRINOS Trying to discern the patterns of neutrino masses and mixing. FEATURES Boris Kayser 42 THE K2K NEUTRINO 4 PAULI’S GHOST EXPERIMENT A seventy-year saga of the conception The world’s first long-baseline and discovery of neutrinos. neutrino experiment is beginning Michael Riordan to produce results. Koichiro Nishikawa & Jeffrey Wilkes 15 MINING SUNSHINE The first results from the Sudbury 50 WHATEVER HAPPENED Neutrino Observatory reveal TO HOT DARK MATTER? the “missing” solar neutrinos.
  • Multi-Messenger Astrophysics with the First Lines of the Km3net Neutrino Telescopes

    Multi-Messenger Astrophysics with the First Lines of the Km3net Neutrino Telescopes

    MULTI-MESSENGER ASTROPHYSICS WITH THE FIRST LINES OF THE KM3NET NEUTRINO TELESCOPES PHD SUPERVISOR : THIERRY PRADIER (MAÎTRE DE CONFÉRENCES) INSTITUT PLURIDISCIPLINAIRE HUBERT CURIEN, DÉPARTEMENT RECHERCHES SUBATOMIQUES 23 RUE DU LOESS BP 28 67037 STRASBOURG CEDEX 2 TEL : 03 88 10 6620 ; E-MAIL : [email protected] The proposed PhD thesis will be performed in the framework of the european collaborations KM3NeT, which use underwater « neutrino telescopes » in the Mediterranean Sea, to detect and study GeV to PeV atmospheric/cosmic neutrinos. IceCube has revealed in 2013 the existence of cosmic neutrinos, yielding information on the origin of cosmic rays. In July 2018, a possible connection of these cosmic neutrinos with astrophysical sources such as blazars was revealed. Moreover, the observation of gravitational waves and electromagnetic radiations from the merger of two neutron stars in 2017, and the search for coincident neutrinos, has opened the field of multi-messenger astrophysics : the combination of photons from all wavelengths, neutrinos, cosmic-rays and gravitational waves to improve our knowledge of astrophysical sources and discover new sources, in which IPHC has taken an active part. In 2019, the next-generation neutrino telescopes built by the KM3NeT collaboration will begin their deployment and data taking, with more than 300 lines on 2 sites to be deployed over a few years. The french site in Toulon will be dedicated to low energy GeV neutrinos, to determine the unknown neutrino mass hierarchy, with ORCA (Oscillation Research with Cosmics in the Abyss). The italian site, in Sicily, will host ARCA (Astroparticle Research with Cosmics in the Abyss), dedicated, like ANTARES, to TeV-PeV neutrino astronomy.
  • 11 – Neutrino Astronomy

    11 – Neutrino Astronomy

    11 – Neutrino astronomy introduc)on to Astrophysics, C. Bertulani, Texas A&M-Commerce 1 11.1 – The standard solar model As we discussed in “stellar evolution III”, to obtain a reliable model for the sun, we need to solve four differential equations (in the absence of convection). dM(r) 2 (11.1) dP(r) GM(r)ρ(r) = 4πr ρ(r) = − (11.2) dr dr r2 dT(r) 3 (r) (r) dL(r) 2 (11.3) ρ κ (11.4) = 4πr ρ(r)ε(r) = − 2 3 L(r) dr dr 16πr σT (r) € € Complemented by P = P (, T, chemical composition)€ The equation of state € κ = κ (, T, chemical composition) Opacity ε = ε (, T, chemical composition) Energy generation But we also need to include how the chemical composition changes through nuclear reaction network. For the sun, the pp-chain and the CNO cycle are considered. introduc)on to Astrophysics, C. Bertulani, Texas A&M-Commerce 2 General reaction network When the reaction network proceeds via one-body and two-body reactions, such as the pp-chain. and CNO cycle. But 3-body processes such as the triple-alpha reaction are also possible. A general reaction network can be written as dYi i i = ∑N j λ jY j + ∑N jk ρNA < σ v > Y jYk + dt j jk (11.5) 2 i 2 ∑N jkm ρ NA < σ v > Y jYkYm +! jkm i where N j,k,l,... is the number of particles of nuclear species i created or destroyed by the reaction j + k + l + · · · à i. € The reactions listed on the right hand side of the equation above belong to three categories of reactions: (1) decays, photodisintegrations, electron and positron captures and neutrino induced reactions (rj = λjnj), (2) two-particle reactions (rj,k =< σv >j,knjnk), and (3) three-particle reactions 12 (rj,k,l =< σv>j,k,lnjnknl) like the triple-alpha process (α + α + α à C + γ).
  • Glossary of Terms Absorption Line a Dark Line at a Particular Wavelength Superimposed Upon a Bright, Continuous Spectrum

    Glossary of Terms Absorption Line a Dark Line at a Particular Wavelength Superimposed Upon a Bright, Continuous Spectrum

    Glossary of terms absorption line A dark line at a particular wavelength superimposed upon a bright, continuous spectrum. Such a spectral line can be formed when electromag- netic radiation, while travelling on its way to an observer, meets a substance; if that substance can absorb energy at that particular wavelength then the observer sees an absorption line. Compare with emission line. accretion disk A disk of gas or dust orbiting a massive object such as a star, a stellar-mass black hole or an active galactic nucleus. An accretion disk plays an important role in the formation of a planetary system around a young star. An accretion disk around a supermassive black hole is thought to be the key mecha- nism powering an active galactic nucleus. active galactic nucleus (agn) A compact region at the center of a galaxy that emits vast amounts of electromagnetic radiation and fast-moving jets of particles; an agn can outshine the rest of the galaxy despite being hardly larger in volume than the Solar System. Various classes of agn exist, including quasars and Seyfert galaxies, but in each case the energy is believed to be generated as matter accretes onto a supermassive black hole. adaptive optics A technique used by large ground-based optical telescopes to remove the blurring affects caused by Earth’s atmosphere. Light from a guide star is used as a calibration source; a complicated system of software and hardware then deforms a small mirror to correct for atmospheric distortions. The mirror shape changes more quickly than the atmosphere itself fluctuates.
  • Foundation Document Manhattan Project National Historical Park Tennessee, New Mexico, Washington January 2017 Foundation Document

    Foundation Document Manhattan Project National Historical Park Tennessee, New Mexico, Washington January 2017 Foundation Document

    NATIONAL PARK SERVICE • U.S. DEPARTMENT OF THE INTERIOR Foundation Document Manhattan Project National Historical Park Tennessee, New Mexico, Washington January 2017 Foundation Document MANHATTAN PROJECT NATIONAL HISTORICAL PARK Hanford Washington ! Los Alamos Oak Ridge New Mexico Tennessee ! ! North 0 700 Kilometers 0 700 Miles More detailed maps of each park location are provided in Appendix E. Manhattan Project National Historical Park Contents Mission of the National Park Service 1 Mission of the Department of Energy 2 Introduction 3 Part 1: Core Components 4 Brief Description of the Park. 4 Oak Ridge, Tennessee. 5 Los Alamos, New Mexico . 6 Hanford, Washington. 7 Park Management . 8 Visitor Access. 8 Brief History of the Manhattan Project . 8 Introduction . 8 Neutrons, Fission, and Chain Reactions . 8 The Atomic Bomb and the Manhattan Project . 9 Bomb Design . 11 The Trinity Test . 11 Hiroshima and Nagasaki, Japan . 12 From the Second World War to the Cold War. 13 Legacy . 14 Park Purpose . 15 Park Signifcance . 16 Fundamental Resources and Values . 18 Related Resources . 22 Interpretive Themes . 26 Part 2: Dynamic Components 27 Special Mandates and Administrative Commitments . 27 Special Mandates . 27 Administrative Commitments . 27 Assessment of Planning and Data Needs . 28 Analysis of Fundamental Resources and Values . 28 Identifcation of Key Issues and Associated Planning and Data Needs . 28 Planning and Data Needs . 31 Part 3: Contributors 36 Appendixes 38 Appendix A: Enabling Legislation for Manhattan Project National Historical Park. 38 Appendix B: Inventory of Administrative Commitments . 43 Appendix C: Fundamental Resources and Values Analysis Tables. 48 Appendix D: Traditionally Associated Tribes . 87 Appendix E: Department of Energy Sites within Manhattan Project National Historical Park .
  • Sc Ence Celebrating the Neutrino Number 25 1997

    Sc Ence Celebrating the Neutrino Number 25 1997

    Los Alamos Sc ence Celebrating the Neutrino Number 25 1997 Celebrating the Neutrino . .1 The Evidence for Oscillations . .116 Bill Louis, Vern Sandberg, Gerry Garvey, Hywel White, Geoffrey Mills, and Rex Tayloe Reines-Cowan Experiments—Detecting the Poltergeist . .4 Neutrino oscillations are invoked as the explanation in experiments with solar, atmospheric, and accelerator- A compilation of papers and notes by Fred Reines and Clyde Cowan, Jr. produced (LSND) neutrinos. This summary of the experimental results for mixing angles and neutrino masses includes an interesting model that makes all three data sets consistent. The neutrino’s existence was inferred by Wolfgang Pauli in 1930, who feared that his clever construct might elude detection forever. Twenty-five years later, Fred Reines, Clyde Cowan, Jr., and a Los Alamos team detected the evasive particle. Their dedication to the chase and their innovative detection techniques set The Nature of Neutrinos in Muon Decay and Physics Beyond the Standard Model . .128 a precedent for all future neutrino experiments. Peter Herczeg Beta Decay and the Missing Energy . .7 Experiments that search for electron antineutrinos from m1-decay are sensitive not only to neutrino oscillations Fermi’s Theory of Beta Decay and Neutrino Processes . .8 but also to a class of muon decays that require leptonic interactions not present in the Standard Model. The author explores whether such decays could explain the observed excess of e1 events in the LSND experiments. The Oscillating Neutrino—An Introduction to Neutrino Masses and Mixing . .28 Exorcising Ghosts—In Pursuit of the Missing Solar Neutrinos . .136 Richard Slansky, Stuart Raby, Terry Goldman, and Gerry Garvey as told to Necia Grant Cooper Andrew Hime Today, the neutrino is at the center of particle physics as experimenters around the world explore the possibility that this tiny particle changes its identity just by moving between two points.
  • Gamma-Ray and Neutrino Astronomy

    Gamma-Ray and Neutrino Astronomy

    Sp.-V/AQuan/1999/10/07:19:58 Page 207 Chapter 10 γ -Ray and Neutrino Astronomy R.E. Lingenfelter and R.E. Rothschild 10.1 Continuum Emission Processes ............. 207 10.2 Line Emission Processes ................. 208 10.3 Scattering and Absorption Processes .......... 213 10.4 Astrophysical γ -Ray Observations ........... 216 10.5 Neutrinos in Astrophysics ................ 235 10.6 Current Neutrino Observatories ............. 237 10.1 CONTINUUM EMISSION PROCESSES Important processes for continuum emission at γ -ray energies are bremsstrahlung, magneto- bremsstrahlung, and Compton scattering of blackbody radiation by energetic electrons and positrons [1–6]. 10.1.1 Bremsstrahlung The bremsstrahlung luminosity spectrum of an optically thin thermal plasma of temperature T in a volume V is [3] 1/2 π 6 π 2 32 e 2 mc 2 L(ν)brem = Z neniVg(ν, T ) exp(−hν/kT), 3m2c4 3kT where the index of refraction is assumed to be unity, m is the electron mass, Z is the mean atomic 1/2 charge, ne and ni are the electron and ion densities, and the Gaunt factor g(ν, T ) ≈ (3kT/πhν) for hν>kT and T > 3.6 × 105 Z 2 K, or −38 2 −1/2 −1 −1 L(ν)brem ≈ 6.8 × 10 Z neniVg(ν, T )T exp(−hν/kT) erg s Hz . 207 Sp.-V/AQuan/1999/10/07:19:58 Page 208 208 / 10 γ -RAY AND NEUTRINO ASTRONOMY 10.1.2 Magnetobremsstrahlung The synchrotron luminosity spectrum of an isotropic, optically thin nonthermal distribution of −S relativistic electrons with a power-law spectrum, N(γ ) = N0γ , interacting with a homogeneous magnetic field of strength, H,is[5] .
  • Dear Astronomers, What Is It That You Do in the Practice of Your Science?

    Dear Astronomers, What Is It That You Do in the Practice of Your Science?

    Dear Astronomers, What is it that you do in the practice of your science? This email is an invitation to participate in a research study that explores the activities in which astronomers currently engage. The goal of the study is to characterize what it is that you do as a practicing astronomer. The results will provide educators, curriculum developers, and others a valuable tool as they work to create more authentic (real-world) experiences, improving astronomy learning for all. Participants in the survey must meet the following 4 requirements: • have one or more science or science related degrees, with at least one at the Masters Degree level or higher, • work primarily in one or more of the astronomy sub-disciplines (if you are unsure, please see definition of astronomy sub-disciplines at the end of this letter), • currently engaged in, or have engaged in, at least one astronomy related research project within the past two years, • and, be an astronomer primarily based in the United States, a U.S. territory, or a U.S. facility in another country. This research study is being conducted by Tim Spuck, a doctoral candidate in Curriculum and Instruction under the supervision of Dr. James Rye, professor in the West Virginia University College of Education and Human Services. This research study is part of a dissertation that is being conducted in partial fulfillment of the requirements of the Curriculum and Instruction Doctoral Program at West Virginia University. Your participation in this study is completely voluntary and consists of completing an online survey, which will take approximately 15 minutes.