Trapped Antihydrogen in Its Ground State

Total Page:16

File Type:pdf, Size:1020Kb

Trapped Antihydrogen in Its Ground State Trapped Antihydrogen in Its Ground State The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Richerme, Philip. 2012. Trapped Antihydrogen in Its Ground State. Doctoral dissertation, Harvard University. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:10058466 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA ©2012 - Philip John Richerme All rights reserved. Thesis advisor Author Gerald Gabrielse Philip John Richerme Trapped Antihydrogen in Its Ground State Abstract Antihydrogen atoms (H) are confined in a magnetic quadrupole trap for 15 to 1000 s - long enough to ensure that they reach their ground state. This milestone brings us closer to the long-term goal of precise spectroscopic comparisons of H and H for tests of CPT and Lorentz invariance. Realizing trapped H requires charac- terization and control of the number, geometry, and temperature of the antiproton (p) and positron (e+) plasmas from which H is formed. An improved apparatus and implementation of plasma measurement and control techniques make available 107 p and 4 × 109 e+ for H experiments - an increase of over an order of magnitude. For the first time, p are observed to be centrifugally separated from the electrons that cool them, indicating a low-temperature, high-density p plasma. Determination of the p temperature is achieved through measurement of the p evaporation rate as their con- fining well is reduced, with corrections given by a particle-in-cell plasma simulation. New applications of electron and adiabatic cooling allow for the lossless reduction in p temperature from thousands of Kelvin to 3.5 K or colder, the lowest ever reported. The sum of the 20 trials performed in 2011 in which p and e+ mix to form H in the presence of a magnetic quadrupole trap reveals a total of 105 ± 21 trapped H, or 5 ± 1 per trial on average. This result paves the way towards the large numbers of simultaneously trapped H that will be necessary for laser spectroscopy. iii Contents Title Page . i Abstract . iii Table of Contents . iv Publications . viii Acknowledgments . ix Dedication . xii 1 Introduction 1 1.1 Precision Measurements with Trapped Antihydrogen . 2 1.1.1 Tests of CPT Symmetry . 2 1.1.2 Gravitational Studies . 8 1.2 A Brief Summary of Antihydrogen Research . 9 1.3 Overview of this work . 11 2 Apparatus 14 2.1 Penning Trap . 17 2.1.1 Theory . 17 2.1.2 Cylindrical Penning Traps . 19 2.1.3 Synchrotron cooling . 27 2.1.4 BTRAP Penning Trap . 28 2.2 Ioffe Trap . 31 2.2.1 Theory . 31 2.2.2 BTRAP Ioffe Trap . 35 2.3 Penning-Ioffe Trap . 39 2.3.1 Charged Particle Trajectories . 39 2.3.2 Non-neutral Plasma Confinement . 43 2.3.3 Antihydrogen Production . 44 2.4 Field-Boosting Solenoid . 46 2.5 X-Y Translation Stage . 47 2.6 1 K Pot . 49 2.7 Scintillating Detectors . 51 iv Contents v 3 Non-neutral Plasmas in a Penning Trap 55 3.1 Plasmas in a Cylindrical Trap . 56 3.2 Plasmas in Penning Traps . 61 3.2.1 Ideal Quadrupole Traps . 61 3.2.2 Non-Ideal Penning Traps . 63 3.3 Plasma Dynamics . 64 3.4 Collision Rates . 68 3.5 Plasma Characterization . 72 3.5.1 Number . 72 3.5.2 Mode Frequencies . 77 3.6 Plasma Control . 79 3.6.1 Cylindrically Symmetric Fields . 80 3.6.2 Rotating Wall . 81 4 Standard Methods 88 4.1 Antiproton Capture . 89 4.1.1 Beam Steering . 89 4.1.2 Antiproton Slowing . 91 4.1.3 Antiproton Trapping . 92 4.1.4 Field-Boosting Solenoid . 94 4.2 Electron Loading . 98 4.3 Antiproton Accumulation . 101 4.3.1 Electrons . 102 4.3.2 Antiproton Stacking . 104 4.3.3 Rotating Wall . 106 4.3.4 Electron Pulse-out . 108 4.3.5 Magnetic Field Reduction . 108 4.3.6 Accumulation Results . 110 4.4 Positron Accumulation . 111 4.5 Particle Transfer . 114 4.6 Antihydrogen Production . 118 4.6.1 Antihydrogen Formation Processes . 118 4.6.2 Antiproton-Positron Mixing . 121 4.6.3 Detection of Antihydrogen . 123 4.6.4 Trappable Antihydrogen . 124 5 Centrifugal Separation of Antiprotons and Electrons 127 5.1 Temperature and Length Scales for Centrifugal Separation . 128 5.2 Density Distribution for Multi-Species Plasmas . 130 5.3 Demonstration by Axial Potential Reduction . 133 5.4 Demonstration by Magnetic Field Reduction . 137 5.5 Summary and Discussion . 140 Contents vi 6 Embedded Electron and Adiabatic Cooling of Antiprotons 142 6.1 Plasma Temperature Measurements . 143 6.1.1 Measurement Procedure . 143 6.1.2 Antiproton Temperature Measurements . 148 6.1.3 Space Charge Correction . 150 6.1.4 Applications and Limitations . 154 6.2 Embedded Electron Cooling . 155 6.2.1 Cooling Efficiency . 157 6.2.2 Embedded Electron Number . 159 6.3 Adiabatic Cooling . 161 6.3.1 Single-Particle Picture . 161 6.3.2 Ideal Gas Picture . 162 6.3.3 Cooling Timescales . 163 6.3.4 Demonstration of Adiabatic Cooling . 164 6.4 Summary and Discussion . 167 7 Trapped Antihydrogen: Searches and Formation Methods 170 7.1 Searches for Trapped Antihydrogen . 171 7.2 Experimental Trials . 180 7.2.1 Noise Drives . 182 7.2.2 Coherent Chirped Drives . 184 7.2.3 Slow Chirped Drives . 187 7.2.4 Chirped Drives with Positron Well Sweep . 188 8 Mirror-Trapped Antiprotons 193 8.1 Mechanism . 194 8.2 Mirror-Trapping On-Axis . 195 8.3 Mirror-Trapping Off-Axis . 197 8.4 Antiproton Energy Scales . 200 9 Trapped Antihydrogen: Event Detection and Findings 204 9.1 Event Detection . 204 9.1.1 Event Classification . 205 9.1.2 Data Thresholding . 208 9.1.3 Monte Carlo Simulation . 211 9.2 Demonstration of Trapped Antihydrogen . 214 9.2.1 Individual Trials . 215 9.2.2 Combined Signal . 218 9.2.3 Ground-State Antihydrogen . 220 9.3 Antimatter Gravity . 222 9.4 Summary and Discussion . 224 Contents vii 10 Electrode Fabrication for an Improved Penning-Ioffe Trap 226 10.1 Electrode Design Constraints . 229 10.1.1 Octupole Field Profile . 229 10.1.2 Induced Currents . 230 10.1.3 Particle Manipulation . 231 10.2 Electrode Body . 232 10.3 Electrode Support Structure . 235 10.4 Penning Trap Assembly . 236 11 Conclusion 239 Bibliography 243 Papers and Publications 1. Efficient transfer of positrons from a buffer-gas-cooled accumulator into an orthogonally oriented superconducting solenoid for antihy- drogen studies D. Comeau, A. Dror, D. W. Fitzakerley, M. C. George, E. A. Hessels, C. H. Storry, M. Weel, D. Grzonka, W. Oelert, G. Gabrielse, R. Kalra, W. S. Koltham- mer, R. McConnell, P. Richerme, A. Müllers, and J. Walz. New J. Phys. 12, 045006 (2012). 2. Trapped Antihydrogen in Its Ground State G. Gabrielse, R. Kalra, W. S. Kolthammer, R. McConnell, P. Richerme, D. Grzonka, W. Oelert, T. Sefzick, M. Zielinski, D. W. Fitzakerley, M. C. George, E. A. Hessels, C. H. Storry, M. Weel, A. Müllers, and J. Walz. Phys. Rev. Lett. 108, 113002 (2012). 3. Adiabatic Cooling of Antiprotons G. Gabrielse, W.S. Kolthammer, R. McConnell, P. Richerme, R. Kalra, E. Novitski, D. Grzonka, W. Oelert, T. Sefzick, M. Zielinski, D. Fitzakerley, M.C. George, E.A. Hessels, C.H. Storry, M. Weel, A. Müllers, and J. Walz. Phys. Rev. Lett. 105, 073002 (2011). 4. Pumped Helium System for Producing 1.2 K Positrons and Electrons J. Wrubel, G. Gabrielse, W.S. Kolthammer, P. Larochelle, R. McConnell, P. Richerme, D. Grzonka, W. Oelert, T. Sefzick, M. Zielinski,.
Recommended publications
  • Confinement of Antihydrogen for 1000 Seconds
    Confinement of antihydrogen for 1000 seconds G.B. Andresen1, M.D. Ashkezari2, M. Baquero-Ruiz3, W. Bertsche4, E. Butler5, C.L. Cesar6, A. Deller4, S. Eriksson4, J. Fajans3#, T. Friesen7, M.C. Fujiwara8,7, D.R. Gill8, A. Gutierrez9, J.S. Hangst1, W.N. Hardy9, R.S. Hayano10, M.E. Hayden2, A.J. Humphries4, R. Hydomako7, S. Jonsell11, S. Kemp5§, L. Kurchaninov8, N. Madsen4, S. Menary12, P. Nolan13, K. Olchanski8, A. Olin8&, P. Pusa13, C.Ø. Rasmussen1, F. Robicheaux14, E. Sarid15, D.M. Silveira16, C. So3, J.W. Storey8$, R.I. Thompson7, D.P. van der Werf4, J.S. Wurtele3#, Y. Yamazaki16¶. 1Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark. 2Department of Physics, Simon Fraser University, Burnaby BC, V5A 1S6, Canada 3Department of Physics, University of California, Berkeley, CA 94720-7300, USA 4Department of Physics, Swansea University, Swansea SA2 8PP, United Kingdom 5Physics Department, CERN, CH-1211, Geneva 23, Switzerland 6Instituto de Fısica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972, Brazil 7Department of Physics and Astronomy, University of Calgary, Calgary AB, T2N 1N4, Canada 8TRIUMF, 4004 Wesbrook Mall, Vancouver BC, V6T 2A3, Canada 9Department of Physics and Astronomy, University of British Columbia, Vancouver BC, V6T 1Z1, Canada 10Department of Physics, University of Tokyo, Tokyo 113-0033, Japan 11 Department of Physics, Stockholm University, SE-10691, Stockholm, Sweden 12Department of Physics and Astronomy, York University, Toronto, ON, M3J 1P3, Canada 13Department of Physics,
    [Show full text]
  • Antimatter Weapons (1946-1986): from Fermi and Teller's
    Antimatter weapons (1946-1986): From Fermi and Teller’s speculations to the first open scientific publications ∗ Andre Gsponer and Jean-Pierre Hurni Independent Scientific Research Institute Box 30, CH-1211 Geneva-12, Switzerland e-mail: [email protected] Version ISRI-86-10.3 June 4, 2018 Abstract We recall the early theoretical speculations on the possible explosive uses of antimatter, from 1946 to the first production of antiprotons, at Berkeley in 1955, and until the first capture of cold antiprotons, at CERN on July 17–18, 1986, as well as the circumstances of the first presentation at a scientific conference of the correct physical processes leading to the ignition of a large scale thermonuclear explosion using less than a few micrograms of antimatter as trigger, at Madrid on June 30th – July 4th, 1986. Preliminary remark This paper will be followed by by Antimatter weapons (1986-2006): From the capture of the first antiprotons to the production of cold antimatter, to appear in 2006. 1 Introduction At CERN (the European Laboratory for Particle Physics), on the evening of the 17 to the 18 of July 1986, antimatter was captured in an electromagnetic trap for arXiv:physics/0507132v2 [physics.hist-ph] 28 Oct 2005 the first time in history. Due to the relatively precarious conditions of this first ∗Expanded version of a paper published in French in La Recherche 17 (Paris, 1986) 1440– 1443; in English in The World Scientist (New Delhi, India, 1987) 74–77, and in Bulletin of Peace Proposals 19 (Oslo,1988) 444–450; and in Finnish in Antimateria-aseet (Kanssainvalinen¨ rauhantutkimuslaitos, Helsinki, 1990, ISBN 951-9193-22-7) 7–18.
    [Show full text]
  • ANTIMATTER a Review of Its Role in the Universe and Its Applications
    A review of its role in the ANTIMATTER universe and its applications THE DISCOVERY OF NATURE’S SYMMETRIES ntimatter plays an intrinsic role in our Aunderstanding of the subatomic world THE UNIVERSE THROUGH THE LOOKING-GLASS C.D. Anderson, Anderson, Emilio VisualSegrè Archives C.D. The beginning of the 20th century or vice versa, it absorbed or emitted saw a cascade of brilliant insights into quanta of electromagnetic radiation the nature of matter and energy. The of definite energy, giving rise to a first was Max Planck’s realisation that characteristic spectrum of bright or energy (in the form of electromagnetic dark lines at specific wavelengths. radiation i.e. light) had discrete values The Austrian physicist, Erwin – it was quantised. The second was Schrödinger laid down a more precise that energy and mass were equivalent, mathematical formulation of this as described by Einstein’s special behaviour based on wave theory and theory of relativity and his iconic probability – quantum mechanics. The first image of a positron track found in cosmic rays equation, E = mc2, where c is the The Schrödinger wave equation could speed of light in a vacuum; the theory predict the spectrum of the simplest or positron; when an electron also predicted that objects behave atom, hydrogen, which consists of met a positron, they would annihilate somewhat differently when moving a single electron orbiting a positive according to Einstein’s equation, proton. However, the spectrum generating two gamma rays in the featured additional lines that were not process. The concept of antimatter explained. In 1928, the British physicist was born.
    [Show full text]
  • New Measurements of the Electron Magnetic Moment and the Fine Structure Constant
    S´eminaire Poincar´eXI (2007) 109 – 146 S´eminaire Poincar´e Probing a Single Isolated Electron: New Measurements of the Electron Magnetic Moment and the Fine Structure Constant Gerald Gabrielse Leverett Professor of Physics Harvard University Cambridge, MA 02138 1 Introduction For these measurements one electron is suspended for months at a time within a cylindrical Penning trap [1], a device that was invented long ago just for this purpose. The cylindrical Penning trap provides an electrostatic quadrupole potential for trapping and detecting a single electron [2]. At the same time, it provides a right, circular microwave cavity that controls the radiation field and density of states for the electron’s cyclotron motion [3]. Quantum jumps between Fock states of the one-electron cyclotron oscillator reveal the quantum limit of a cyclotron [4]. With a surrounding cavity inhibiting synchrotron radiation 140-fold, the jumps show as long as a 13 s Fock state lifetime, and a cyclotron in thermal equilibrium with 1.6 to 4.2 K blackbody photons. These disappear by 80 mK, a temperature 50 times lower than previously achieved with an isolated elementary particle. The cyclotron stays in its ground state until a resonant photon is injected. A quantum cyclotron offers a new route to measuring the electron magnetic moment and the fine structure constant. The use of electronic feedback is a key element in working with the one-electron quantum cyclotron. A one-electron oscillator is cooled from 5.2 K to 850 mK us- ing electronic feedback [5]. Novel quantum jump thermometry reveals a Boltzmann distribution of oscillator energies and directly measures the corresponding temper- ature.
    [Show full text]
  • Antihydrogen and the Antiproton Magnetic Moment
    Gabrielse ATRAP: Context and Status Antihydrogen and the Antiproton Magnetic Moment Gerald Gabrielse Spokesperson for TRAP and ATRAP at CERN Levere tt Pro fesso r o f Phys ics, Har var d Uni ver sit y Gabrielse Context CERN Pursues Fundamental Particle Physics at WWeveegySceseesghatever Energy Scale is Interesting A Long and Noble CERN Tradition 1981 – traveled to Fermilab “TEV or bust” 1985 – different response at CERN wh en I went th ere to try to get access to LEAR antiprotons for qqyg/m measurements and cold antihydrogen It is exciting that there is now • a dedicated storaggge ring for antih ygpydrogen experiments • four international collaborations • too few antiprotons for the demand Gabrielse Pursuing Fundamental Particle Physics atWhtt Whatever Energy Sca le is In teres ting A Long and Noble CERN Tradition 1986 – First trapped antiprotons (TRAP) 1989 – First electron-cooling of trapped antiprotons (TRAP) 1 cm magnetic field 21 MeV antiprotons slow in matter degrader _ + _ CERN’s AD, plus these cold methods make antihydrogen possible Gabrielse Pursuing Fundamental Particle Physics atWhtt Whatever Energy Sca le is In teres ting A Long and Noble CERN Tradition 1981 – traveled to Fermilab “TEV or bust” 1985 – different response at CERN when I went there to try to get access to LEAR antiprotons for q/m measurements and cold antihydrogen LHC: 7 TeV + 7 TeV AD: 5 MeV 100 times 5 x 1016 More trapped ELENA upgrade: 0.1 MeV antiprotons ATRAP: 0.3 milli-eV Gabrielse Physics With Low Energy Antiprotons First Physics: Compare q/m for antiproton
    [Show full text]
  • Patentable Subject [Anti]Matter
    PATENTABLE SUBJECT [ANTI]MATTER Whether antihydrogen qualifies as patentable subject matter for the purposes of the United States patent law is not an easy question. In general, man-made inventions and new compositions of matter are proper subjects of patent protection, while products of nature are not. Antihydrogen, a newly created element made entirely of antimatter, has qualities of both a newly created composition of matter and a product of nature. As a result, antihydrogen approaches the theoretical boundaries of the product of nature doctrine because mankind finally has the opportunity to create for the very first time an element that has probably never existed before in the entire universe. This iBrief will begin by briefly explaining antimatter and antihydrogen. Then, a distinction will be drawn between a man-made invention and a product of nature by analyzing relevant case law. Finally, antihydrogen will be analyzed as hypothetical subject matter under the United States patent laws without considering the further requirements of novelty and non-obviousness. An Overview of Antimatter and Antihydrogen Antimatter In 1930, the theoretical physicist Paul Dirac predicted that for every particle of matter, there exists an equivalent particle of antimatter.1 The existence of antimatter was confirmed in 1933 with the discovery of the positron, the antimatter pair of the electron.2 The theory does not mean to say that every proton in the universe must have a ghostly antiproton pair; rather it simply means that matter in the universe can be made of “real” matter, like protons and electrons, or it can be made of antimatter, like antiprotons and positrons.
    [Show full text]
  • Harvard University Department of Physics Newsletter
    Harvard University Department of Physics Newsletter FALL 2014 COVER STORY Probing the Universe’s Earliest Moments FOCUS Early History of the Physics Department FEATURED Quantum Optics Where Physics Meets Biology Condensed Matter Physics NEWS A Reunion Across Generations and Disciplines 42475.indd 1 10/30/14 9:19 AM Detecting this signal is one of the most important goals in cosmology today. A lot of work by a lot of people has led to this point. JOHN KOVAC, HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS LEADER OF THE BICEP2 COLLABORATION 42475.indd 2 10/24/14 12:38 PM CONTENTS ON THE COVER: Letter from the former Chair ........................................................................................................ 2 The BICEP2 telescope at Physics Department Highlights 4 twilight, which occurs only ........................................................................................................ twice a year at the South Pole. The MAPO observatory (home of the Keck Array COVER STORY telescope) and the South Pole Probing the Universe’s Earliest Moments ................................................................................. 8 station can be seen in the background. (Steffen Richter, Harvard University) FOCUS ACKNOWLEDGMENTS Early History of the Physics Department ................................................................................ 12 AND CREDITS: Newsletter Committee: FEATURED Professor Melissa Franklin Professor Gerald Holton Quantum Optics ..............................................................................................................................14
    [Show full text]
  • Daily Newsletter – Wednesday, 29 July Neutrino Physics Flavour
    Daily Newsletter – Wednesday, 29 July The finale of a great conference in a wonderful related with the CKM-triangle. We expect city still has a lot to offer! Here comes the to see there the latest result published on overview. Monday in Nature Physics by the LHCb collaboration. The second presentation will summarise the rare decays and exotic Neutrino PhysiCs states, including information about the Sterile neutrinos with masses in different recently discovered pentaquark. Low energy ranges are physically very energy precision experiments, like interesting objects. Such neutrinos, with measurements of the lepton magnetic masses in the GeV range, could make an moment or studies using antihydrogen, important contribution to solving the will be summarised by Gerald Gabrielse. puzzle of matter-antimatter asymmetry in the universe, while keV-mass sterile neutrinos could constitute dark matter. Higgs and New PhysiCs The quest to find sterile neutrinos in the On the last day of the conference, two eV mass range, which might relieve talks will cover the experimental status of tensions in the findings of short baseline the search for new physics. experiments, is close to its end. The Supersymmetry is one of the best absolute neutrino mass scale of the three motivated extensions of the Standard standard neutrinos is still not known, Model and a first talk will provide though the possible range of the heaviest highlights of the searches for of the three has been narrowed down to supersymmetric particles performed so far the sub-eV range. The main objective of at the LHC. A second talk will give an experiments trying to find neutrinoless overview of the territory covered by the double beta decay is to discover whether LHC Run 1 searches for exotic neutrinos have Majorana nature, i.e., if experimental signatures in a large variety they are their own antiparticles.
    [Show full text]
  • Antihydrogen Synthesis Via Magnetobound States of Protonium Within Proton-Positron-Antiproton Plasmas
    43rd EPS Conference on Plasma Physics P4.112 Antihydrogen Synthesis Via Magnetobound States of Protonium Within Proton-Positron-Antiproton Plasmas M. Hermosillo, C. A. Ordonez University of North Texas, Denton, Texas, USA Through classical trajectory simulation, the possibility that antihydrogen can be synthesized via three body recombination involving magnetobound protonium is studied. It has been previ- ously reported that proton-antiproton collisions can result in a correlated drift of the particles perpendicular to a magnetic field. While the two particles are in their correlated drift, they are referred to as a magnetobound protonium system. Possible three body recombination resulting in bound state antihydrogen is studied when a magnetobound protonium system encounters a positron. The simulation incorporates a uniform magnetic field. A visual search and an energy analysis was done in an attempt to find parameters for which the positron is captured into a bound state with an antiproton, resulting in the formation of antihydrogen. Recently, simulations have shown that within a low temperature plasma containing protons and antiprotons, binary collisons invloving proton-antiproton pairs can cause them to become bound temporarily and experience giant cross-magnetic field drifts [1, 2]. These particle pairs have been referred to as being in a magnetobound state, which could serve as a useful intermedi- ate step in the production of neutral antimatter. Magnetobound states occur in low temperatures and strong magnetic fields such as those found inside Penning traps that produce antihydrogen. The possibility of three body recombination resulting in bound state antihydrogen is studied when a magnetobound protonium system encounters a positron. The interactions between particles throughout the simulation are treated classically.
    [Show full text]
  • Antihydrogen Physicsweb.Org Probing the Antiworld
    Feature: Antihydrogen physicsweb.org Probing the antiworld One of the most staggering achievements in quantum physics was Paul Dirac’s prediction of the anti-electron in 1930. By tirelessly modifying Schrödinger’s descrip- tion of the electron until it was consistent with special relativity, Dirac derived a beautiful equation that had additional “negative energy” solutions. He proposed that these solutions corresponded to a particle that has the same mass as the electron but the opposite electri- cal charge. Three years later the world’s first antipar- ticle – called the positron – was discovered by Carl Anderson at the California Institute of Technology. But Dirac’s vision for antimatter did not stop there. By 1931 he had realized that the only other elementary particle known at that time – the proton – should also have a corresponding antiparticle: the antiproton. This particle was discovered at Berkeley in October 1955 (see box on page 32), setting the stage for the creation of atoms made entirely from antimatter. A positron and an antiproton form the simplest type of anti-atom – antihydrogen. However, getting these two antiparticles to come together and form a single atomic system is no mean feat, not least because anti- matter immediately annihilates when it comes into con- tact with ordinary matter. So why have physicists even bothered trying for the past 50 years? Asymmetric world When we look out at the universe from our vantage point here on Earth, one thing is clear: it is dominated by matter. Irrespective of how or where we look, anti- matter simply does not exist in the quantities we would of the properties of anti-atoms provide a unique way expect if matter and antimatter had been created in to test this once and for all.
    [Show full text]
  • Trapped Antihydrogen : Nature : Nature Publishing Group Page 1 of 8
    Trapped antihydrogen : Nature : Nature Publishing Group Page 1 of 8 nature.com Sitemap Log In Register Archive Volume 468 Issue 7324 Letters Article NATURE | LETTER Trapped antihydrogen G. B. Andresen, M. D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, P. D. Bowe, E. Butler, C. L. Cesar, S. Chapman, M. Charlton, A. Deller, S. Eriksson, J. Fajans, T. Friesen, M. C. Fujiwara, D. R. Gill, A. Gutierrez, J. S. Hangst, W. N. Hardy, M. E. Hayden, A. J. Humphries, R. Hydomako, M. J. Jenkins, S. Jonsell, L. V. Jørgensen, L. Kurchaninov et al. Nature 468, 673–676 (02 December 2010) doi:10.1038/nature09610 Received 08 October 2010 Accepted 27 October 2010 Published online 17 November 2010 Antimatter was first predicted1 in 1931, by Dirac. Work with high-energy antiparticles is now commonplace, and anti-electrons are used regularly in the medical technique of positron emission tomography scanning. Antihydrogen, the bound state of an antiproton and a positron, has been produced2, 3 at low energies at CERN (the European Organization for Nuclear Research) since 2002. Antihydrogen is of interest for use in a precision test of nature’s fundamental symmetries. The charge conjugation/parity/time reversal (CPT) theorem, a crucial part of the foundation of the standard model of elementary particles and interactions, demands that hydrogen and antihydrogen have the same spectrum. Given the current experimental precision of measurements on the hydrogen atom (about two parts in 1014 for the frequency of the 1s-to-2s transition 4), subjecting antihydrogen to rigorous spectroscopic examination would constitute a compelling, model-independent test of CPT.
    [Show full text]
  • Precision Pins Down the Electron's Magnetism
    CCOctELECTRON35-37 20/9/06 11:14 Page 35 PHYSICAL CONSTANTS Precision pins down the electron’s magnetism A measurement of the electron magnetic Dear Gerald…As one of the inventors [of QED], I remember that we thought of QED in 1949 as a temporary and jerry-built moment using the combination of several structure, with mathematical inconsistencies and renormalized leading-edge techniques has achieved new infinities swept under the rug. We did not expect it to last more than 10 years before some more solidly built theory would levels of accuracy, yielding a more precise replace it...Now, 57 years have gone by and that ramshackle structure still stands...It is amazing that you can measure her value for the fine structure constant. dance to one part per trillion and find her still following our beat. Gerald Gabrielse and David Hanneke With congratulations and good wishes for more such beautiful experiments, yours ever, Freeman Dyson. (Dyson 2006). describe this remarkable experiment. The electron’s magnetic moment has recently been measured to an of its low energy and by locating the electron in the centre of a accuracy of 7.6 parts in 1013 (Odom et al. 2006). As figure 1a microwave cavity. The damping time is typically about 10 seconds, (p36) indicates, this is a six-fold improvement on the last measure- about 1024 times slower than for a 104 GeV electron in the Large ment of this moment made nearly 20 years ago (Van Dyck et al. Electron–Positron collider (LEP). To confine the electron weakly we 1987).
    [Show full text]