Photon-Photon Scattering and Related Things
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Glossary Physics (I-Introduction)
1 Glossary Physics (I-introduction) - Efficiency: The percent of the work put into a machine that is converted into useful work output; = work done / energy used [-]. = eta In machines: The work output of any machine cannot exceed the work input (<=100%); in an ideal machine, where no energy is transformed into heat: work(input) = work(output), =100%. Energy: The property of a system that enables it to do work. Conservation o. E.: Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. Equilibrium: The state of an object when not acted upon by a net force or net torque; an object in equilibrium may be at rest or moving at uniform velocity - not accelerating. Mechanical E.: The state of an object or system of objects for which any impressed forces cancels to zero and no acceleration occurs. Dynamic E.: Object is moving without experiencing acceleration. Static E.: Object is at rest.F Force: The influence that can cause an object to be accelerated or retarded; is always in the direction of the net force, hence a vector quantity; the four elementary forces are: Electromagnetic F.: Is an attraction or repulsion G, gravit. const.6.672E-11[Nm2/kg2] between electric charges: d, distance [m] 2 2 2 2 F = 1/(40) (q1q2/d ) [(CC/m )(Nm /C )] = [N] m,M, mass [kg] Gravitational F.: Is a mutual attraction between all masses: q, charge [As] [C] 2 2 2 2 F = GmM/d [Nm /kg kg 1/m ] = [N] 0, dielectric constant Strong F.: (nuclear force) Acts within the nuclei of atoms: 8.854E-12 [C2/Nm2] [F/m] 2 2 2 2 2 F = 1/(40) (e /d ) [(CC/m )(Nm /C )] = [N] , 3.14 [-] Weak F.: Manifests itself in special reactions among elementary e, 1.60210 E-19 [As] [C] particles, such as the reaction that occur in radioactive decay. -
1 the History of Vacuum Science and Vacuum Technology
1 1 The History of Vacuum Science and Vacuum Technology The Greek philosopher Democritus (circa 460 to 375 B.C.), Fig. 1.1, assumed that the world would be made up of many small and undividable particles that he called atoms (atomos, Greek: undividable). In between the atoms, Democritus presumed empty space (a kind of micro-vacuum) through which the atoms moved according to the general laws of mechanics. Variations in shape, orientation, and arrangement of the atoms would cause variations of macroscopic objects. Acknowledging this philosophy, Democritus,together with his teacher Leucippus, may be considered as the inventors of the concept of vacuum. For them, the empty space was the precondition for the variety of our world, since it allowed the atoms to move about and arrange themselves freely. Our modern view of physics corresponds very closely to this idea of Democritus. However, his philosophy did not dominate the way of thinking until the 16th century. It was Aristotle’s (384 to 322 B.C.) philosophy, which prevailed throughout theMiddleAgesanduntilthebeginning of modern times. In his book Physica [1], around 330 B.C., Aristotle denied the existence of an empty space. Where there is nothing, space could not be defined. For this reason no vacuum (Latin: empty space, emptiness) could exist in nature. According to his philosophy, nature consisted of water, earth, air, and fire. The lightest of these four elements, fire, is directed upwards, the heaviest, earth, downwards. Additionally, nature would forbid vacuum since neither up nor down could be defined within it. Around 1300, the medieval scholastics began to speak of a horror vacui, meaning nature’s fear of vacuum. -
A Study of the Effects of Pair Production and Axionlike Particle
Washington University in St. Louis Washington University Open Scholarship Arts & Sciences Electronic Theses and Dissertations Arts & Sciences Summer 8-15-2016 A Study of the Effects of Pair Production and Axionlike Particle Oscillations on Very High Energy Gamma Rays from the Crab Pulsar Avery Michael Archer Washington University in St. Louis Follow this and additional works at: https://openscholarship.wustl.edu/art_sci_etds Recommended Citation Archer, Avery Michael, "A Study of the Effects of Pair Production and Axionlike Particle Oscillations on Very High Energy Gamma Rays from the Crab Pulsar" (2016). Arts & Sciences Electronic Theses and Dissertations. 828. https://openscholarship.wustl.edu/art_sci_etds/828 This Dissertation is brought to you for free and open access by the Arts & Sciences at Washington University Open Scholarship. It has been accepted for inclusion in Arts & Sciences Electronic Theses and Dissertations by an authorized administrator of Washington University Open Scholarship. For more information, please contact [email protected]. WASHINGTON UNIVERSITY IN ST. LOUIS Department of Physics Dissertation Examination Committee: James Buckley, Chair Francesc Ferrer Viktor Gruev Henric Krawzcynski Michael Ogilvie A Study of the Effects of Pair Production and Axionlike Particle Oscillations on Very High Energy Gamma Rays from the Crab Pulsar by Avery Michael Archer A dissertation presented to the Graduate School of Arts and Sciences of Washington University in partial fulfillment of the requirements for the degree of Doctor of Philosophy August 2016 Saint Louis, Missouri copyright by Avery Michael Archer 2016 Contents List of Tablesv List of Figures vi Acknowledgments xvi Abstract xix 1 Introduction1 1.1 Gamma-Ray Astronomy............................. 1 1.2 Pulsars...................................... -
7. Gamma and X-Ray Interactions in Matter
Photon interactions in matter Gamma- and X-Ray • Compton effect • Photoelectric effect Interactions in Matter • Pair production • Rayleigh (coherent) scattering Chapter 7 • Photonuclear interactions F.A. Attix, Introduction to Radiological Kinematics Physics and Radiation Dosimetry Interaction cross sections Energy-transfer cross sections Mass attenuation coefficients 1 2 Compton interaction A.H. Compton • Inelastic photon scattering by an electron • Arthur Holly Compton (September 10, 1892 – March 15, 1962) • Main assumption: the electron struck by the • Received Nobel prize in physics 1927 for incoming photon is unbound and stationary his discovery of the Compton effect – The largest contribution from binding is under • Was a key figure in the Manhattan Project, condition of high Z, low energy and creation of first nuclear reactor, which went critical in December 1942 – Under these conditions photoelectric effect is dominant Born and buried in • Consider two aspects: kinematics and cross Wooster, OH http://en.wikipedia.org/wiki/Arthur_Compton sections http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=22551 3 4 Compton interaction: Kinematics Compton interaction: Kinematics • An earlier theory of -ray scattering by Thomson, based on observations only at low energies, predicted that the scattered photon should always have the same energy as the incident one, regardless of h or • The failure of the Thomson theory to describe high-energy photon scattering necessitated the • Inelastic collision • After the collision the electron departs -
String-Inspired Running Vacuum—The ``Vacuumon''—And the Swampland Criteria
universe Article String-Inspired Running Vacuum—The “Vacuumon”—And the Swampland Criteria Nick E. Mavromatos 1 , Joan Solà Peracaula 2,* and Spyros Basilakos 3,4 1 Theoretical Particle Physics and Cosmology Group, Physics Department, King’s College London, Strand, London WC2R 2LS, UK; [email protected] 2 Departament de Física Quàntica i Astrofísica, and Institute of Cosmos Sciences (ICCUB), Universitat de Barcelona, Av. Diagonal 647, E-08028 Barcelona, Catalonia, Spain 3 Academy of Athens, Research Center for Astronomy and Applied Mathematics, Soranou Efessiou 4, 11527 Athens, Greece; [email protected] 4 National Observatory of Athens, Lofos Nymfon, 11852 Athens, Greece * Correspondence: [email protected] Received: 15 October 2020; Accepted: 17 November 2020; Published: 20 November 2020 Abstract: We elaborate further on the compatibility of the “vacuumon potential” that characterises the inflationary phase of the running vacuum model (RVM) with the swampland criteria. The work is motivated by the fact that, as demonstrated recently by the authors, the RVM framework can be derived as an effective gravitational field theory stemming from underlying microscopic (critical) string theory models with gravitational anomalies, involving condensation of primordial gravitational waves. Although believed to be a classical scalar field description, not representing a fully fledged quantum field, we show here that the vacuumon potential satisfies certain swampland criteria for the relevant regime of parameters and field range. We link the criteria to the Gibbons–Hawking entropy that has been argued to characterise the RVM during the de Sitter phase. These results imply that the vacuumon may, after all, admit under certain conditions, a rôle as a quantum field during the inflationary (almost de Sitter) phase of the running vacuum. -
Arxiv:1809.04815V2 [Physics.Hist-Ph] 28 Jan 2020
Who discovered positron annihilation? Tim Dunker∗ (Dated: 29 January 2020) In the early 1930s, the positron, pair production, and, at last, positron annihila- tion were discovered. Over the years, several scientists have been credited with the discovery of the annihilation radiation. Commonly, Thibaud and Joliot have received credit for the discovery of positron annihilation. A conversation between Werner Heisenberg and Theodor Heiting prompted me to examine relevant publi- cations, when these were submitted and published, and how experimental results were interpreted in the relevant articles. I argue that it was Theodor Heiting— usually not mentioned at all in relevant publications—who discovered positron annihilation, and that he should receive proper credit. arXiv:1809.04815v2 [physics.hist-ph] 28 Jan 2020 ∗ tdu {at} justervesenet {dot} no 2 I. INTRODUCTION There is no doubt that the positron was discovered by Carl D. Anderson (e.g. Anderson, 1932; Hanson, 1961; Leone and Robotti, 2012) after its theoretical prediction by Paul A. M. Dirac (Dirac, 1928, 1931). Further, it is undoubted that Patrick M. S. Blackett and Giovanni P. S. Occhialini discovered pair production by taking photographs of electrons and positrons created from cosmic rays in a Wilson cloud chamber (Blackett and Occhialini, 1933). The answer to the question who experimentally discovered the reverse process—positron annihilation—has been less clear. Usually, Frédéric Joliot and Jean Thibaud receive credit for its discovery (e.g., Roqué, 1997, p. 110). Several of their contemporaries were enganged in similar research. In a letter correspondence with Werner Heisenberg Heiting and Heisenberg (1952), Theodor Heiting (see Appendix A for a rudimentary biography) claimed that it was he who discovered positron annihilation. -
Riccar Radiance
Description of the vacuum R40 & R40P Owner’s Manual CONTENTS Getting Started Important Safety Instructions .................................................................................................... 2 Polarization Instructions ............................................................................................................. 3 State of California Proposition 65 Warnings ...................................................................... 3 Description of the Vacuum ........................................................................................................ 4 Assembling the Vacuum Attaching the Handle to the Vacuum ..................................................................................... 6 Unwinding the Power Cord ...................................................................................................... 6 Operation Reclining the Handle .................................................................................................................. 7 Vacuuming Carpet ....................................................................................................................... 7 Bare Floor Cleaning .................................................................................................................... 7 Brushroll Auto Shutoff Feature ................................................................................................. 7 Dirt Sensing Display .................................................................................................................. -
Pkoduction of RELATIVISTIC ANTIHYDROGEN ATOMS by PAIR PRODUCTION with POSITRON CAPTURE*
SLAC-PUB-5850 May 1993 (T/E) PkODUCTION OF RELATIVISTIC ANTIHYDROGEN ATOMS BY PAIR PRODUCTION WITH POSITRON CAPTURE* Charles T. Munger and Stanley J. Brodsky Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309 .~ and _- Ivan Schmidt _ _.._ Universidad Federico Santa Maria _. - .Casilla. 11 O-V, Valparaiso, Chile . ABSTRACT A beam of relativistic antihydrogen atoms-the bound state (Fe+)-can be created by circulating the beam of an antiproton storage ring through an internal gas target . An antiproton that passes through the Coulomb field of a nucleus of charge 2 will create e+e- pairs, and antihydrogen will form when a positron is created in a bound rather than a continuum state about the antiproton. The - cross section for this process is calculated to be N 4Z2 pb for antiproton momenta above 6 GeV/c. The gas target of Fermilab Accumulator experiment E760 has already produced an unobserved N 34 antihydrogen atoms, and a sample of _ N 760 is expected in 1995 from the successor experiment E835. No other source of antihydrogen exists. A simple method for detecting relativistic antihydrogen , - is -proposed and a method outlined of measuring the antihydrogen Lamb shift .g- ‘,. to N 1%. Submitted to Physical Review D *Work supported in part by Department of Energy contract DE-AC03-76SF00515 fSLAC’1 and in Dart bv Fondo National de InvestiPaci6n Cientifica v TecnoMcica. Chile. I. INTRODUCTION Antihydrogen, the simplest atomic bound state of antimatter, rf =, (e+$, has never. been observed. A 1on g- sought goal of atomic physics is to produce sufficient numbers of antihydrogen atoms to confirm the CPT invariance of bound states in quantum electrodynamics; for example, by verifying the equivalence of the+&/2 - 2.Py2 Lamb shifts of H and I?. -
The Use of a Lunar Vacuum Deposition Paver/Rover To
Developing a New Space Economy (2019) 5014.pdf The Use of a Lunar Vacuum Deposition Paver/Rover to Eliminate Hazardous Dust Plumes on the Lunar Sur- face Alex Ignatiev and Elliot Carol, Lunar Resources, Inc., Houston, TX ([email protected], elliot@lunarre- sources.space) References: [1] A. Cohen “Report of the 90-Day Study on Hu- man Exploration of the Moon and Mars”, NASA, Nov. 1989 [2] A. Freunlich, T. Kubricht, and A. Ignatiev: “Lu- nar Regolith Thin Films: Vacuum Evaporation and Properties,” AP Conf. Proc., Vol 420, (1998) p. 660 [3] Sadoway, D.R.: “Electrolytic Production of Met- als Using Consumable Anodes,” US Patent No. © 2018 Lunar Resources, Inc. 5,185,068, February 9, 1993 [4] Duke, M.B.: Blair, B.: and J. Diaz: “Lunar Re- source Utilization,” Advanced Space Research, Vol. 31(2002) p.2413. Figure 1, Lunar Resources Solar Cell Paver concept [5] A. Ignatiev, A. Freundlich.: “The Use of Lunar surface vehicle Resources for Energy Generation on the Moon,” Introduction: The indigenous resources of the Moon and its natural vacuum can be used to prepare and construct various assets for future Outposts and Bases on the Moon. Based on available lunar resources and the Moon’s ultra-strong vacuum, a vacuum deposition paver/rover can be used to melt regolith into glass to eliminate dust plumes during landing operations and surface activities on the Moon. This can be accom- plished by the deployment of a moderately-sized (~200kg) crawler/rover on the surface of the Moon with the capabilities of preparing and then melting of the lu- nar regolith into a glass on the Lunar surface. -
Electron-Positron Pairs in Physics and Astrophysics
Electron-positron pairs in physics and astrophysics: from heavy nuclei to black holes Remo Ruffini1,2,3, Gregory Vereshchagin1 and She-Sheng Xue1 1 ICRANet and ICRA, p.le della Repubblica 10, 65100 Pescara, Italy, 2 Dip. di Fisica, Universit`adi Roma “La Sapienza”, Piazzale Aldo Moro 5, I-00185 Roma, Italy, 3 ICRANet, Universit´ede Nice Sophia Antipolis, Grand Chˆateau, BP 2135, 28, avenue de Valrose, 06103 NICE CEDEX 2, France. Abstract Due to the interaction of physics and astrophysics we are witnessing in these years a splendid synthesis of theoretical, experimental and observational results originating from three fundamental physical processes. They were originally proposed by Dirac, by Breit and Wheeler and by Sauter, Heisenberg, Euler and Schwinger. For almost seventy years they have all three been followed by a continued effort of experimental verification on Earth-based experiments. The Dirac process, e+e 2γ, has been by − → far the most successful. It has obtained extremely accurate experimental verification and has led as well to an enormous number of new physics in possibly one of the most fruitful experimental avenues by introduction of storage rings in Frascati and followed by the largest accelerators worldwide: DESY, SLAC etc. The Breit–Wheeler process, 2γ e+e , although conceptually simple, being the inverse process of the Dirac one, → − has been by far one of the most difficult to be verified experimentally. Only recently, through the technology based on free electron X-ray laser and its numerous applications in Earth-based experiments, some first indications of its possible verification have been reached. The vacuum polarization process in strong electromagnetic field, pioneered by Sauter, Heisenberg, Euler and Schwinger, introduced the concept of critical electric 2 3 field Ec = mec /(e ). -
Introduction to the Principles of Vacuum Physics
1 INTRODUCTION TO THE PRINCIPLES OF VACUUM PHYSICS Niels Marquardt Institute for Accelerator Physics and Synchrotron Radiation, University of Dortmund, 44221 Dortmund, Germany Abstract Vacuum physics is the necessary condition for scientific research and modern high technology. In this introduction to the physics and technology of vacuum the basic concepts of a gas composed of atoms and molecules are presented. These gas particles are contained in a partially empty volume forming the vacuum. The fundamentals of vacuum, molecular density, pressure, velocity distribution, mean free path, particle velocity, conductivity, temperature and gas flow are discussed. 1. INTRODUCTION — DEFINITION, HISTORY AND APPLICATIONS OF VACUUM The word "vacuum" comes from the Latin "vacua", which means "empty". However, there does not exist a totally empty space in nature, there is no "ideal vacuum". Vacuum is only a partially empty space, where some of the air and other gases have been removed from a gas containing volume ("gas" comes from the Greek word "chaos" = infinite, empty space). In other words, vacuum means any volume containing less gas particles, atoms and molecules (a lower particle density and gas pressure), than there are in the surrounding outside atmosphere. Accordingly, vacuum is the gaseous environment at pressures below atmosphere. Since the times of the famous Greek philosophers, Demokritos (460-370 B.C.) and his teacher Leukippos (5th century B.C.), one is discussing the concept of vacuum and is speculating whether there might exist an absolutely empty space, in contrast to the matter of countless numbers of indivisible atoms forming the universe. It was Aristotle (384-322 B.C.), who claimed that nature is afraid of total emptiness and that there is an insurmountable "horror vacui". -
Worldline Sphaleron for Thermal Schwinger Pair Production
IMPERIAL-TP-2018-OG-1 HIP-2018-17-TH Worldline sphaleron for thermal Schwinger pair production Oliver Gould,1, 2, ∗ Arttu Rajantie,1, y and Cheng Xie1, z 1Department of Physics, Imperial College London, SW7 2AZ, UK 2Helsinki Institute of Physics, University of Helsinki, FI-00014, Finland (Dated: August 24, 2018) With increasing temperatures, Schwinger pair production changes from a quantum tunnelling to a classical, thermal process, determined by a worldline sphaleron. We show this and calculate the corresponding rate of pair production for both spinor and scalar quantum electrodynamics, including the semiclassical prefactor. For electron-positron pair production from a thermal bath of photons and in the presence of an electric field, the rate we derive is faster than both perturbative photon fusion and the zero temperature Schwinger process. We work to all-orders in the coupling and hence our results are also relevant to the pair production of (strongly coupled) magnetic monopoles in heavy-ion collisions. I. INTRODUCTION Schwinger rate, Γ(E; T ), takes the form, 1 In non-Abelian gauge theories, sphaleron processes, X Γ(E; T ) = c h(J · A)ni; (1) or thermal over-barrier transitions, have long been un- n derstood to dominate over quantum tunnelling transi- n=0 1 tions at high enough temperatures [1{4] . The same is where E is the magnitude of the electric field and T is true, for example, in gravitational theories [5]. On the the temperature. The leading term, c0, gives the one loop other hand, sphalerons have been conspicuously absent result, that of Schwinger [6], at zero temperature.