DOCSLIB.ORG

Skyrmion Behavior Revealed by Two X-Ray Studies J.C.T

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Skyrmion Behavior Revealed by Two X-Ray Studies J.C.T MATERIALS / CONDENSED MATTER PUBLISHED BY THE ADVANCED LIGHT SOURCE COMMUNICATIONS GROUP Publications about this research: M.C. Langner, S. Roy, S.K. Mishra, Skyrmion Behavior Revealed by Two X-Ray Studies J.C.T. Lee, X.W. Shi, M.A. Hossain, Y.-D. Chuang, S. Seki, Y. Tokura, S.D. Kevan, and R.W. Schoenlein, Sometimes, the spins in a “Coupled Skyrmion Sublattices in magnetic material will form Cu2OSeO3,” Phys. Rev. Lett. 112, tiny swirls that can move 167202 (2014); J. Li, A. Tan, K.W. around like particles. The spins Moon, A. Doran, M.A. Marcus, A.T. Young, E. Arenholz, S. Ma, themselves stay put—it’s the R.F. Yang, C. Hwang, and Z.Q. Qiu, pattern that moves. These “Tailoring the topology of an quasiparticles have been artificial magnetic skyrmion,” Nat. dubbed “skyrmions,” after Commun. 5, 4704 (2014). British physicist Tony Skyrme, Research conducted by: M.C. who described their mathe- Langner and R.W. Schoenlein matics in a series of papers in (Berkeley Lab); S. Roy, S.K. the early 1960s. Now, over 50 Mishra, J.C.T. Lee, X.W. Shi, M.A. years later, scientists are Hossain, Y.-D. Chuang, A. Doran, intrigued by the possibility that M.A. Marcus, A.T. Young, and E. skyrmions could play a key role Arenholz (ALS); S. Seki (RIKEN in spintronics—electronics that and Japan Science and Technology employ spin to carry and mani- Agency); Y. Tokura (RIKEN and Univ. of Tokyo); S.D. Kevan (ALS upulate information. At the and Univ. of Oregon); J. Li, A. Tan, ALS, two research groups have S. Ma, R.F. Yang, and Z.Q. Qiu recently published separate (Univ. of California, Berkeley); and studies in which soft x-rays K.W. Moon and C. Hwang (Korea reveal how skyrmions react to A skyrmion is an atom-sized whirlwind of magnetism, in which Research Institute of Standards external fields, laying the foun- the spins of charged particles form a vortex. In this image, the and Science). color scale—red for longer and blue for shorter vectors—shows dation for understanding and Research funding: U.S. Department eventually utilizing these fasci- that the magnetization is highest at the center of the skyrmion. of Energy (DOE), Office of Basic nating constructs. (Image by Matthew Langner) Energy Sciences (BES); National Although skyrmions act Science Foundation; National like particles (namely, baryons), Research Foundation of Korea; they are actually magnetic Add to this the discovery tron orbitals stabilize the and China Scholarship Council. vortices formed from the spins that skyrmions can be moved skyrmionic phase. Until now, Operation of the ALS is supported by DOE BES. of charged particles. Spin is a coherently over macroscopic the copper selenite skyrmions quantum property in which distances with a tiny electrical had only been observed with the charged particles act like current, and you have a strong neutron scattering and trans- bar magnets rotating about an spintronic candidate. mission electron microscopy, axis that points either “up” A major breakthrough techniques that are insensitive or “down.” The discovery of came with the discovery of to electron orbitals. skyrmions in manganese sili- skyrmions in copper selenite In one skyrmion study cide generated much excite- because its magnetic proper- done at the ALS, researchers ment because their exotic ties can be controlled with an gathered element-specific, hedgehog-like spin texture is electric field. To achieve this orbital-sensitive electronic and topologically protected and, control, however, we must magnetic structural informa- therefore, extremely stable. understand how different elec- tion using resonant x-ray scat- Particles, Practically Why do some particles decay while others do not? What is a particle, anyway? Physicists long ago moved beyond the idea of permanent, indivisible “atoms” of matter to increasingly abstract concepts such as wave-particle dualities and quan- tum field theories that treat particles as excited states in an underlying “particle” field. If these treatments were not quite as satisfying at an intuitive level, at least they worked, pre- dicting phenomena such as interference effects and limited particle lifetimes. Skyrmions, the product of one such treatment, have been Soft x-ray diffraction images from copper selenide show five sets resurrected from particle physics to find new application as of dual-peak skyrmion structures, highlighted by the white ovals. quasiparticles in condensed matter physics, where they The dual peaks represent the two skyrmion sublattices that rotate emerge from complex interactions between spins, orbitals, with respect to each other. All peaks fall on an arc (white line) low dimensionality, and external fields. A key feature of mag- representing the constant amplitude of the skyrmion wave vector. netic skyrmions is that they are topologically protected: because their spin structures cannot be continuously deformed into other magnetic states, they don’t “decay.” The combination of this stability, their nanometer size, and the low magnetic and electric fields required for manipulating them makes skyrmions practical particles for spintronic applications and high-density information storage. Skyrmion PEEM images after the application of an in-plane tering at Beamline 12.0.2, tions that can’t exist in mate- magnetic field pulse (skyrmion core annihilation process) for (a) N=0 optimized for coherent x-ray rials with a single magnetic and (b) and N=1. The central vortex is surrounded by out-of-plane scattering studies of magnetic lattice structure. nickel spins as indicated by the yellow symbols. A lower critical materials. They were able to In another study, a second field is needed to annihilate the core for N=0 compared to N=1. show that although skyrmions research group created artifi- act like magnetic particles, cial skyrmions in 30-nm-thick their origin in copper selenite cobalt disks on 30-monolayer to control the formation of the skyrmions (parallel). This is electronic and that tempera- nickel, all on a copper substrate. two states in this system. distinct behavior for the two ture can be used to move the This structure created two To study the skyrmions’ states suggests a topological skyrmions in either a clockwise magnetic regions: the area topological nature, the effect of the magnetic skyrmions or counter-clockwise direction. in/under the cobalt disk researchers annihilated the in the core annihilation process. They also found the unex- (in-plane magnetization), and skyrmions by applying an The exploration of the pected existence of two the surrounding nickel (out-of- in-plane magnetic pulse that world of magnetic skyrmions distinct skyrmion sublattices plane magnetization). This was pushed the core out of the disk, is just beginning, but it that rotate with respect to each important because skyrmions converting the vortex into a already reveals that these other, creating a moiré-like can be characterized by a simple magnetic domain. Photo- particle-like spin configura- pattern. Compared to materials skyrmion number (N) equal to 0 emission electron microscopy tions not only hold promise with a simpler magnetic struc- when the core and surrounding (PEEM) measurements at for ultracompact data storage ture, the sublattices provide for spins are parallel, and 1 when Beamline 11.0.1 revealed that and processing, but they may an extra degree of freedom to they are antiparallel. By applying N=1 skyrmions (antiparallel) also open up entirely new minimize the free energy. various out-of-plane magnetic required a higher critical field areas of study in the emerging This leads to magnetic excita- fields, the researchers were able for annihilation than N=0 field of quantum topology. 298 09/14 More ALS science highlights can be found at www-als.lbl.gov.
Load more

Recommended publications
  • 01 Freer.Pdf
    John Henry Poynting First Prof Physics Birmingham 1880-1914 Rudolf Peierls 1907-1995 Birmingham 1937+ (holes in semiconductors) Marcus Laurence Elwin Oliphant 1901-2000 Birmingham 1937-1950 Otto Frisch (1904-1979) Bham 1939+ co-discover of 2H, 3H and 3He Role in first demonstration of nuclear fusion Got plans from Lawrence for Birmingham’s cyclotron John Bell 1928-1990 CPT 1951 Birmingham Luders-Pauli Thm Freeman-Dyson Tony Skyrme (1922-1987) Birmingham, 1949-51 Why are light nuclei so important – Understanding cutting edge theory ? [Otsuka et al., PRL 95 (05) 232502] Tensor correlations [Otsuka et al., PRL 97 (06) 162501] Neutron – proton interaction - - - + + + + - 8Be Ab initio type approaches (Greens Function Monte Carlo) 13 11 + 9 4 7 Ex [MeV] [MeV] Ex Ex 5 3 2+ 1 + -1 0 -1 4 9 14 19 24 Pieper and J(J+1) Wiringa, ANL 9 Ab initio no-core solutions for nuclear structure: Be P. Maris, C. Cockrell, M. Caprio and J.P. Vary Total density Proton - Neutron density Shows that one neutron provides a “ring ” cloud around two alpha clusters binding them together Chase Cockrell, ISU PhD student 12 C Chiral EFT on the lattice 32 S 24 Mg 9Be 9B PHYSICAL REVIEW C 86 , 057306 (2012), PHYSICAL REVIEW C 86 , 014312 (2012) 10 Be 12 C 10 C Characterization of 10 Be * Gas inlet LAMP array Window (2.5 um mylar) LAMP 6He LEDA LAMP LEDA Collimator M. Freer, et al. PRL 2006 Test of method- measure 10.36 MeV 4 + resonance In 16 O ( 12 C+ α) LAMP LEDA LAMP LEDA Resonances in 16 O E( 12 C)=16 MeV Singles Coincidence 10 10 4He Energy Energy (MeV) (MeV) 12 C 0 0 8 24 8 24 Angle Angle Gas pressure = 100 Torr LAMP LEDA LAMP 4 Energy ( 12 C) LEDA θcm ( He) 180 0 Energy ( 4He) 12 180 θcm ( C) Resonance analysis Counts 6000 - =121 mm detector 2000 - (E, θw) ddet window Distance/2+20 (mm) θw θlab dreaction 2 |P 4(cos( θcm )| θcm 6He+ 4He at 7.5 MeV – 7Li+ 7Li the 10.15 MeV state in 10 Be N.
    [Show full text]
  • The Skyrme Model Fundamentals Methods Applications
    springer.com Physics : Elementary Particles, Quantum Field Theory Makhankov, V.G., Rybakov, Y.P., Sanyuk, V.I. The Skyrme Model Fundamentals Methods Applications The December 1988 issue of the International Journal of Modern Physics A is dedicated to the memory of Tony Hilton Royle Skyrme. It contains an informative account of his life by Dalitz and Aitchison's reconstruction of a talk by Skyrme on the origin of the Skyrme model. From these pages, we learn that Tony Skyrme was born in England in December 1922. He grew up in that country during a period of increasing economic and political turbulence in Europe and elsewhere. In 1943, after Cambridge, he joined the British war effort in making the atomic bomb. He was associated with military projects throughout the war years and began his career as an academic theoretical physicist only in 1946. During 1946-61, he was associated with Cambridge, Birmingham and Harwell and was engaged in wide-ranging investigations in nuclear physics. It was this research which eventually culminated in his studies of nonlinear field theories and his remarkable proposals for the description of the nucleon as a chiral soliton. In his talk, Skyrme described the reasons behind his extraordinary sug• gestions, which Springer when first made must have seemed bizarre. According to him, ideas of this sort go back many Softcover reprint of the decades and occur in the work of Sir William Thomson, who later became Lord Kelvin. Skyrme 1st original 1st ed. 1993, XVIII, edition had heard of Kelvin in his youth. 265 p. Order online at springer.com/booksellers Springer Nature Customer Service Center LLC Printed book 233 Spring Street Softcover New York, NY 10013 Printed book USA Softcover T: +1-800-SPRINGER NATURE ISBN 978-3-642-84672-4 (777-4643) or 212-460-1500 [email protected] $ 109,99 Available Discount group Professional Books (2) Product category Monograph Series Springer Series in Nuclear and Particle Physics Other renditions Softcover ISBN 978-3-642-84671-7 Prices and other details are subject to change without notice.
    [Show full text]
  • Topology in Physics-A Perspective
    SU-4228-533 March 1993 TOPOLOGY IN PHYSICS - A PERSPECTIVE A.P. Balachandran Department of Physics, Syracuse University, Syracuse, NY 13244-1130 ABSTRACT This article, written in honour of Fritz Rohrlich, briefly surveys the role of topology in physics. arXiv:hep-th/9303177v1 31 Mar 1993 When I joined Syracuse University as a junior faculty member in September, 1964, Fritz Rohrlich was already there as a senior theoretician in the quantum field theory group. He was a very well-known physicist by that time, having made fundamental contributions to quantum field theory, and written his splendid book with Jauch. My generation of physicists grew up with Jauch and Rohrlich, and I was also familiar with Fritz’s research. It was therefore with a certain awe and a great deal of respect that I first made his acquaintance. Many years have passed since this first encounter. Our interests too have gradually evolved and changed in this intervening time. Starting from the late seventies or there- abouts, particle physicists have witnessed an increasing intrusion of topological ideas into their discipline. Our group at Syracuse has responded to this development by getting involved in soliton and monopole physics and in investigations on the role of topology in quantum physics. Meanwhile, especially during the last decade, there has been a per- ceptible shift in the direction of Fritz’s research to foundations and history of quantum physics. Later I will argue that topology affects the nature of wave functions (or more accurately of wave functions in the domains of observables) and has a profound meaning for the fundamentals of quantum theory.
    [Show full text]
  • Quark•Gluon Plasma
    news & views GRAPHENE The running of the constants To first approximation, the dispersion relation around the Fermi energy of single-layer graphene is linear, making its charge carriers behave like massless relativistic subatomic particles. More careful inspection of its low-energy band structure suggests the picture is more complex, extending the analogy even further. Maria A. H. Vozmediano he best times in Physics are those when a α–1 b physicists of different expertise meet around a problem of common interest. 3 T ) And this is now happening in the case of 120 3 –1 α–1 2 graphene. From the early days of the isolation QED ms of single sheets of graphene, the relativistic 6 100 (10 1 F nature of its charge carriers was clear . v These carriers, known as Dirac fermions, are 1 described by equations similar to those that 80 10 E (meV) 100 describe the quantum electrodynamic (QED) interactions of relativistic charged particles. 60 2 U(1) ѵ ~ α–1 A meticulous study performed by Elias and F G 2 co-workers of the electronic structure of 40 SU(2) graphene shows that at very low energies reaching a few meV of graphene’s Dirac point, 20 where its cone-like valence and conduction SU(3) bands touch, the shape of the conduction and valence bands diverge from a simple linear 1 0 2 4 6 8 10 12 14 16 1 2 relation. The result implies that the analogy log E (Gev) log E (10–12 Gev) between graphene and high-energy physics 10 10 is deeper than first expected.
    [Show full text]
  • Bertlmann – a Nonlocal Quantum Engineer
    a nonlocal quantum engineer contemplate but don’t forget to calculate ! Reinhold A. Bertlmann Faculty of Physics, University of Vienna talk at symposium “ shut up and contemplate ! ” University of Vienna, March 3rd, 2017 engineer’s career at Harwell John Stewart Bell graduated at Queen’s University Belfast in experimental physics 1948 in mathematical physics 1949 high interest in quantum mechanics showing his dissatisfaction ! position at AERE Harwell from1949 on joined accelerator group of Walkinshaw (Malvern) William Walkinshaw: John on his new “Ariel” “ a young man of high caliber who showed his at Harwell 1952 independence … his mathematical talent was superb and elegant.” papers on electron and proton linear accelerators e.g. “basic algebra on strong focussing systems” “linear accelerator phase oscillations” “phase debunching by focussing foils in proton linear accelerator” Reinhold A. Bertlmann 2 turn to particle physics & Bohm’s qm in mid1950s Bell turned to nuclear and particle physics “time reversal in field theory …”, CPT theorem, PhD thesis fundamental ! “anomalous magnetic moments of nucleons”, collab. Tony Skyrme at that time paper of David Bohm appeared 1952 “interpretation of quantum theory in terms of hidden variable” Mary: for John a “revelation” “everything has definite properties” I remember John saying Bell’s talk about Bohm’s theory in TH division fierce debates with audience especially with Franz Mandl 1954 John married Mary Ross “mathematical engineer” accelerator physicist Reinhold A. Bertlmann 3 engineer’s job
    [Show full text]
  • Aspects of the Many-Body Problem in Nuclear Physics
    Aspects of the Many-Body Problem in Nuclear Physics DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Alexander Signatur Dyhdalo, MSc, BSc Graduate Program in Physics The Ohio State University 2018 Dissertation Committee: Prof. Richard Furnstahl, Advisor Prof. Robert Perry Prof. Michael Lisa Prof. Junko Shigemitsu c Copyright by Alexander Signatur Dyhdalo 2018 Abstract Low-energy nuclear physics has seen a renaissance of activity recently with the advent of the nuclear effective field theory (EFT) approach, the power of renormalization group techniques, and advances in the computational cost-effectiveness and sophistication of quan- tum many-body methods. Nevertheless challenges remain in part from ambiguities of the nuclear Hamiltonian via regulator artifacts and the scaling of the many-body methods to heavier systems. Regulator artifacts arise due to a renormalization inconsistency in the nuclear EFT as currently formulated in Weinberg power counting, though their ultimate impact on nuclear observables is unknown at present. This results in a residual cutoff dependence in the EFT to all orders. We undertake an examination of these regulator artifacts using perturba- tive energy calculations of uniform matter as a testbed. Our methodology has found that the choice of regulator determines the shape of the energy phase space and that different regulators weight distinct phase space regions differently. Concerning many-body calculations, at present only phenomenological energy density functionals are able to solve for the full table of nuclides. However these functionals are currently unconnected to QCD and have no existing method for systematic improvement.
    [Show full text]
  • An Assessment of Unequal Masses of Atoms Moving in Geometry of Two Component Fermion System
    International Journal of Science and Advanced Innovative Research ISSN: 2536-7315 (Print) 2536-7323 (Online) Volume 5, Number 2, June 2020 http://www.casirmediapublishing.com AN ASSESSMENT OF UNEQUAL MASSES OF ATOMS MOVING IN GEOMETRY OF TWO COMPONENT FERMION SYSTEM ¹E. W. Likta, ²M. A. Abdul Azeez and 3 M. F. Haque ¹Department of Physics, University of Maiduguri, P.M.B 1069, Maiduguri, Borno State. ²Department of Physics Abubakar Tafawa Balewa University, Bauchi, P.M.B 0248, Bauchi, ¹E-Mail: [email protected] ABSTRACT The goal of this paper is to obtain the unequal masses of the atoms moving in geometry of two component fermions system. The two component fermions systems have been considered. The fermion-dimer scattering length 푎푓푑 and dimer- dimer scattering length 푎푑푑 in the universal limit of large fermion-fermion scattering length 푎푓푓 have been computed. The scattering properties of the fermion-dimer, dimer-dimer and the mass ratio dependence of the universal fermion-dimer and universal dimer-dimer scattering length have been analyzed. Scattering properties of composed system indicate a deep understanding of the dynamics in many-body of an atom system. Key word: Atoms, fermion-fermion, fermion-dimer, dimer-dimer and Hamiltonian INTRODUCTION In particle physics, a fermion is a particle that follows Fermi–Dirac statistics. These particles obey the Pauli Exclusion Principle. Fermions include all quarks and leptons, as well as all composite particles made of an odd number of these, such as all baryons and many atoms and nuclei. Fermions differ from bosons, which obey Bose–Einstein statistics. A fermion can be an elementary particle, such as the electron, or it can be a composite particle, such as the proton.
    [Show full text]
  • BRITISH SCIENTISTS and the MANHATTAN PROJECT Also by Ferenc Morton Szasz
    BRITISH SCIENTISTS AND THE MANHATTAN PROJECT Also by Ferenc Morton Szasz THE DIVIDED MIND OF PROTESTANT AMERICA RELIGION IN THE WEST (editor) THE DAY THE SUN ROSE TWICE: The Story of the Trinity Site Nuclear Explosion, July 16, 1945 THE PROTESTANT CLERGY IN THE GREAT PLAINS AND MOUNTAIN WEST British Scientists and the Manhattan Project The Los Alamos Years Ferenc Morton Szasz Professor of History University of New Mexico, Albuquerque MMACMILLAN © Ferenc Morton Szasz 1992 Softcover reprint of the hardcover 1st edition 1992 All rights reserved. No reproduction, copy or transmission of this publication may be made without written permission. No paragraph of this pub1ication may be reproduced, copied or transmitted save with written permission or in accordance with the provisions of the Copyright, Designs and Patents Act 1988, or under the terms of any 1icence permitting 1imited copying issued by the Copyright Licensing Agency, 33-4 A1fred P1ace, London WClE 7DP. Any person who does any unauthorised act in relation to this publication may be liab1e to crimina1 prosecution and civil claims for darnages. First published 1992 by MACMILLAN ACADEMIC AND PROFESSIONAL LTD. Houndmills, Basingstoke, Hampshire RG21 2XS andLondon Companies and representatives throughout the world ISBN 978-1-349-12733-7 ISBN 978-1-349-12731-3 (eBook) DOI 10.1007/978-1-349-12731-3 A catalogue record for this book is available from the British Library. For Margaret and Maria Contents Preface IX Introduction Xlll Background 2 The British Mission at Los Alamos: The Scientific
    [Show full text]
  • A Nonlocal Quantum Engineer Contemplate but Don’T Forget to Calculate !
    a nonlocal quantum engineer contemplate but don’t forget to calculate ! Reinhold A. Bertlmann Faculty of Physics, University of Vienna talk at symposium “ shut up and contemplate ! ” University of Vienna, March 3rd, 2017 engineer’s career at Harwell John Stewart Bell graduated at Queen’s University Belfast in experimental physics 1948 in mathematical physics 1949 high interest in quantum mechanics showing his dissatisfaction ! position at AERE Harwell from1949 on joined accelerator group of Walkinshaw (Malvern) William Walkinshaw: John on his new “Ariel” “ a young man of high caliber who showed his at Harwell 1952 independence … his mathematical talent was superb and elegant.” papers on electron and proton linear accelerators e.g. “basic algebra on strong focussing systems” “linear accelerator phase oscillations” “phase debunching by focussing foils in proton linear accelerator” Reinhold A. Bertlmann 2 turn to particle physics & Bohm’s qm in mid1950s Bell turned to nuclear and particle physics “time reversal in field theory …”, CPT theorem, PhD thesis fundamental ! “anomalous magnetic moments of nucleons”, collab. Tony Skyrme at that time paper of David Bohm appeared 1952 “interpretation of quantum theory in terms of hidden variable” Mary: for John a “revelation” “everything has definite properties” I remember John saying Bell’s talk about Bohm’s theory in TH division fierce debates with audience especially with Franz Mandl 1954 John married Mary Ross “mathematical engineer” accelerator physicist Reinhold A. Bertlmann 3 engineer’s job
    [Show full text]
  • Skyrmions and Biskyrmions in Magnetic Films
    City University of New York (CUNY) CUNY Academic Works Dissertations, Theses, and Capstone Projects CUNY Graduate Center 6-2021 Skyrmions and Biskyrmions in Magnetic Films Daniel Capic The Graduate Center, City University of New York How does access to this work benefit ou?y Let us know! More information about this work at: https://academicworks.cuny.edu/gc_etds/4286 Discover additional works at: https://academicworks.cuny.edu This work is made publicly available by the City University of New York (CUNY). Contact: [email protected] Skyrmions and Biskyrmions in Magnetic Films by Daniel Capic A dissertation submitted to the Graduate Faculty in Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy, The City University of New York 2021 ii c 2021 Daniel Capic All Rights Reserved iii Skyrmions and Biskyrmions in Magnetic Films by Daniel Capic This manuscript has been read and accepted by the Graduate Faculty in Physics in satisfaction of the dissertation requirement for the degree of Doctor of Philosophy. Date Eugene M. Chudnovsky Chair of Examining Committee Date Alexios Polychronakos Executive Officer Supervisory Committee: Dmitry A. Garanin Pouyan Ghaemi Andrew Kent Sergey Vitkalov The City University of New York iv Skyrmions and Biskyrmions in Magnetic Films by Daniel Capic Advisor: Distinguished Professor Eugene M. Chudnovsky Co-advisor: Professor Dmitry A. Garanin Skyrmions have garnered significant attention in condensed matter systems in recent years. In principle, they are topologically protected, so there is a large energy barrier preventing their annihilation. Furthermore, they can exist at the nanoscale, be manipulated with very small currents, and be created by a number of different methods.
    [Show full text]
  • Proton - Wikipedia Page 1 of 10
    Proton - Wikipedia Page 1 of 10 Proton From Wikipedia, the free encyclopedia + A proton is a subatomic particle, symbol p or p , with a Proton positive electric charge of +1e elementary charge and mass slightly less than that of a neutron. Protons and neutrons, each with masses of approximately one atomic mass unit, are collectively referred to as "nucleons". One or more protons are present in the nucleus of every atom. They are a necessary part of the nucleus. The number of protons in the nucleus is the defining property of an element, and is referred to as the atomic number (represented by the symbol Z). Since each element has a unique number of protons, each element has its own unique atomic number. The word proton is Greek for "first", and this name was given to the hydrogen nucleus by Ernest Rutherford in 1920. In previous years Rutherford had discovered that the hydrogen nucleus (known to be the lightest nucleus) could be extracted from the nuclei of nitrogen by collision. Protons were therefore a The quark structure of a proton. The color assignment of candidate to be a fundamental particle and a building block individual quarks is arbitrary, but all three colors must be of nitrogen and all other heavier atomic nuclei. present. Forces between quarks are mediated by gluons. In the modern Standard Model of particle physics, protons Classification Baryon are hadrons, and like neutrons, the other nucleon (particle Composition 2 up quarks, 1 down quark present in atomic nuclei), are composed of three quarks. Statistics Fermionic Although protons were originally considered fundamental or elementary particles, they are now known to be composed of Interactions Gravity, electromagnetic, weak, three valence quarks: two up quarks and one down quark.
    [Show full text]
  • The University of Birmingham's Alumni Magazine
    OLDJOETHE UNIVERSITY OF BIRMINGHAM’S ALUMNI MAGAZINE Autumn 2014 Shaping the future by creating history The supermarket scientist Reflections of an astronaut Keeping UoB in the family Meet the new Chancellor 2 OLD JOE THE FIRST WORD The firstword he inscription over the entrance to the Great Hall records: ‘From August GUEST EDITOR T 1914 to April 1919 these buildings were used by the military authorities as the 1st Southern General Hospital. Within these walls men died What a testament it is to our for their country. Let those who come after wonderful university that many of us live in the same service’. By the end of the do keep it in the family (page 19). First World War, more than 64,000 wounded My amazing dad, Stephen, was soldiers had been treated in campus buildings awarded his PGCE by the University requisitioned by the War Office. of Birmingham in 1993 (with two As we embark on a four-year programme of national and global events BScs already under his belt). I like to commemorating the centenary of the First World War, it is a fitting time to reflect think that my youngest daughter has on the many ways in which the University’s alumni, staff, and students contributed just added to the tradition, having to the war effort. graduated this summer, complete While academic work was suspended from 1914 to 1918, the skills of our with cap and gown, from The Oaks, alumni and staff were brought to bear in a variety of ways: from the design of tank one of the two day nurseries owned radiators and engine parts to investigating the technology of poison gas and aiding and managed by the University! in the development of wireless telegraphy.
    [Show full text]