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Measurements of Elastic Electron-Proton Scattering at Large Momentum Transfer*
SLAC-PUB-4395 Rev. January 1993 m Measurements of Elastic Electron-Proton Scattering at Large Momentum Transfer* A. F. SILL,(~) R. G. ARNOLD,P. E. BOSTED,~. C. CHANG,@) J. GoMEz,(~)A. T. KATRAMATOU,C. J. MARTOFF, G. G. PETRATOS,(~)A. A. RAHBAR,S. E. ROCK,AND Z. M. SZALATA Department of Physics The American University, Washington DC 20016 D.J. SHERDEN Stanford Linear Accelerator Center , Stanford University, Stanford, California 94309 J. M. LAMBERT Department of Physics Georgetown University, Washington DC 20057 and R. M. LOMBARD-NELSEN De’partemente de Physique Nucle’aire CEN Saclay, Gif-sur- Yvette, 91191 Cedex, France Submitted to Physical Review D *Work supported by US Department of Energy contract DE-AC03-76SF00515 (SLAC), and National Science Foundation Grants PHY83-40337 and PHY85-10549 (American University). R. M. Lombard-Nelsen was supported by C. N. R. S. (French National Center for Scientific Research). Javier Gomez was partially supported by CONICIT, Venezuela. (‘)Present address: Department of Physics and Astronomy, University of Rochester, NY 14627. (*)Permanent address: Department of Physics and Astronomy, University of Maryland, College Park, MD 20742. (C)Present address: Continuous Electron Beam Accelerator Facility, Newport News, VA 23606. (d)Present address: Temple University, Philadelphia, PA 19122. (c)Present address: Stanford Linear Accelerator Center, Stanford CA 94309. ABSTRACT Measurements of the forward-angle differential cross section for elastic electron-proton scattering were made in the range of momentum transfer from Q2 = 2.9 to 31.3 (GeV/c)2 using an electron beam at the Stanford Linear Accel- erator Center. The data span six orders of magnitude in cross section. -
The Lamb Shift Experiment in Muonic Hydrogen
The Lamb Shift Experiment in Muonic Hydrogen Dissertation submitted to the Physics Faculty of the Ludwig{Maximilians{University Munich by Aldo Sady Antognini from Bellinzona, Switzerland Munich, November 2005 1st Referee : Prof. Dr. Theodor W. H¨ansch 2nd Referee : Prof. Dr. Dietrich Habs Date of the Oral Examination : December 21, 2005 Even if I don't think, I am. Itsuo Tsuda Je suis ou` je ne pense pas, je pense ou` je ne suis pas. Jacques Lacan A mia mamma e mio papa` con tanto amore Abstract The subject of this thesis is the muonic hydrogen (µ−p) Lamb shift experiment being performed at the Paul Scherrer Institute, Switzerland. Its goal is to measure the 2S 2P − energy difference in µp atoms by laser spectroscopy and to deduce the proton root{mean{ −3 square (rms) charge radius rp with 10 precision, an order of magnitude better than presently known. This would make it possible to test bound{state quantum electrody- namics (QED) in hydrogen at the relative accuracy level of 10−7, and will lead to an improvement in the determination of the Rydberg constant by more than a factor of seven. Moreover it will represent a benchmark for QCD theories. The experiment is based on the measurement of the energy difference between the F=1 F=2 2S1=2 and 2P3=2 levels in µp atoms to a precision of 30 ppm, using a pulsed laser tunable at wavelengths around 6 µm. Negative muons from a unique low{energy muon beam are −1 stopped at a rate of 70 s in 0.6 hPa of H2 gas. -
Muonium-Antimuonium Conversion Abstract
SciPost Phys. Proc. 5, 009 (2021) Muonium-antimuonium conversion Lorenz Willmann? and Klaus Jungmann Van Swinderen Institute, University of Groningen, 9747 AA, Groningen, The Netherlands ? [email protected] Review of Particle Physics at PSI doi:10.21468/SciPostPhysProc.5 Abstract The MACS experiment performed at PSI in the 1990s provided an yet unchallenged upper bound on the probability for a spontaneous conversion of the muonium atom, + + M =(µ e−), into its antiatom, antimuonium M =(µ−e ). It comprises the culmination of a series of measurements at various accelerator laboratories worldwide. The experimen- tal limits on the process have provided input and steering for the further development of a variety of theoretical models beyond the standard theory, in particular for mod- els which address lepton number violating processes and matter-antimatter oscillations. Several models beyond the standard theory could be strongly disfavored. There is inter- est in a new measurement and improved sensitivity could be reached by exploiting the time evolution of the conversion process, e.g., at intense pulsed muonium sources. Copyright L. Willmann and K. Jungmann. Received 16-02-2021 This work is licensed under the Creative Commons Accepted 28-04-2021 Check for Attribution 4.0 International License. Published 06-09-2021 updates Published by the SciPost Foundation. doi:10.21468/SciPostPhysProc.5.009 9.1 Introduction + The bound state of a positive muon (µ ) and an electron (e−) is an exotic atom which has been named muonium (M) by V.Telegdi. This exotic atom was first produced and observed by V.W. Hughes and collaborators in 1960 [1]. -
Hadronic Light-By-Light Contribution to $(G-2) \Mu $ from Lattice QCD: A
MITP/21-019 CERN-TH-2021-047 Hadronic light-by-light contribution to (g − 2)µ from lattice QCD: a complete calculation En-Hung Chao,1 Renwick J. Hudspith,1 Antoine G´erardin,2 Jeremy R. Green,3 Harvey B. Meyer,1, 4, 5 and Konstantin Ottnad1 1PRISMA+ Cluster of Excellence & Institut f¨urKernphysik, Johannes Gutenberg-Universit¨atMainz, D-55099 Mainz, Germany 2Aix Marseille Univ, Universit´ede Toulon, CNRS, CPT, Marseille, France 3Theoretical Physics Department, CERN, 1211 Geneva 23, Switzerland 4Helmholtz Institut Mainz, Staudingerweg 18, D-55128 Mainz, Germany 5GSI Helmholtzzentrum f¨urSchwerionenforschung, Darmstadt, Germany (Dated: April 7, 2021) We compute the hadronic light-by-light scattering contribution to the muon g 2 − from the up, down, and strange-quark sector directly using lattice QCD. Our calcu- lation features evaluations of all possible Wick-contractions of the relevant hadronic four-point function and incorporates several different pion masses, volumes, and lattice-spacings. We obtain a value of aHlbl = 106:8(14:7) 10−11 (adding statistical µ × and systematic errors in quadrature), which is consistent with current phenomenolog- ical estimates and a previous lattice determination. It now appears conclusive that the hadronic light-by-light contribution cannot explain the current tension between theory and experiment for the muon g 2. − I. INTRODUCTION The anomalous magnetic moment of the muon, aµ (g 2)µ=2, is one of the most precisely measured quantities of the Standard Model (SM)≡ of− particle physics. Its value is of considerable interest to the physics community as, currently, there exists a 3:7σ tension between the experimental determination of Ref. -
Neutron Scattering
Neutron Scattering Basic properties of neutron and electron neutron electron −27 −31 mass mkn =×1.675 10 g mke =×9.109 10 g charge 0 e spin s = ½ s = ½ −e= −e= magnetic dipole moment µnn= gs with gn = 3.826 µee= gs with ge = 2.0 2mn 2me =22k 2π =22k Ek== E = 2m λ 2m energy n e 81.81 150.26 Em[]eV = 2 Ee[]V = 2 λ ⎣⎡Å⎦⎤ λ ⎣⎦⎡⎤Å interaction with matter: Coulomb interaction — 9 strong-force interaction 9 — magnetic dipole-dipole 9 9 interaction Several salient features are apparent from this table: – electrons are charged and experience strong, long-range Coulomb interactions in a solid. They therefore typically only penetrate a few atomic layers into the solid. Electron scattering is therefore a surface-sensitive probe. Neutrons are uncharged and do not experience Coulomb interaction. The strong-force interaction is naturally strong but very short-range, and the magnetic interaction is long-range but weak. Neutrons therefore penetrate deeply into most materials, so that neutron scattering is a bulk probe. – Electrons with wavelengths comparable to interatomic distances (λ ~2Å ) have energies of several tens of electron volts, comparable to energies of plasmons and interband transitions in solids. Electron scattering is therefore well suited as a probe of these high-energy excitations. Neutrons with λ ~2Å have energies of several tens of meV , comparable to the thermal energies kTB at room temperature. These so-called “thermal neutrons” are excellent probes of low-energy excitations such as lattice vibrations and spin waves with energies in the meV range. -
Compton Sources of Electromagnetic Radiation∗
August 25, 2010 13:33 WSPC/INSTRUCTION FILE RAST˙Compton Reviews of Accelerator Science and Technology Vol. 1 (2008) 1–16 c World Scientific Publishing Company COMPTON SOURCES OF ELECTROMAGNETIC RADIATION∗ GEOFFREY KRAFFT Center for Advanced Studies of Accelerators, Jefferson Laboratory, 12050 Jefferson Ave. Newport News, Virginia 23606, United States of America kraff[email protected] GERD PRIEBE Division Leader High Field Laboratory, Max-Born-Institute, Max-Born-Straße 2 A Berlin, 12489, Germany [email protected] When a relativistic electron beam interacts with a high-field laser beam, the beam electrons can radiate intense and highly collimated electromagnetic radiation through Compton scattering. Through relativistic upshifting and the relativistic Doppler effect, highly energetic polarized photons are radiated along the electron beam motion when the electrons interact with the laser light. For example, X-ray radiation can be obtained when optical lasers are scattered from electrons of tens of MeV beam energy. Because of the desirable properties of the radiation produced, many groups around the world have been designing, building, and utilizing Compton sources for a wide variety of purposes. In this review paper, we discuss the generation and properties of the scattered radiation, the types of Compton source devices that have been constructed to present, and the future prospects of radiation sources of this general type. Due to the possibilities to produce hard electromagnetic radiation in a device small compared to the alternative storage ring sources, it is foreseen that large numbers of such sources may be constructed in the future. Keywords: Compton backscattering, Inverse Compton source, Thomson scattering, X-rays, Spectral brilliance 1. -
Angular Distribution Measurement of Beam-Foil Muonium Part II: Muon Injection Simulation for a New Muon G-2 Experiment
LAr-12380-T DE93 002178 Part I: Angular Distribution Measurement of Beam-Foil Muonium Part II: Muon Injection Simulation for a New Muon g-2 Experiment Hyo Eun Ahn* 'Guest Scientist at Los Alamos. Department of Physics, Yale University, New Haven, CT 06511-8167. DISTFUDUTiCN Of-' TH5S DOCUMENT 16 f7\\C^ /A\ fl^ir?Trr)/?^i(^ Los A|amos National Laboratoryy L ^© ZAiUaiLI LJ U\VJ& LoL s Alamos.NeAlN w MexicMi o 8754875455 Acknowledgement s I thank my advisor, Vernon Hughes, for his support and guidance throughout the last five years and for providing me an opportunity to work on both muonium experiments at LAMPF and the simulation study on muon g—2 experiment at BNL. I am grateful to Walter Lysenko for introducing me to the simulation study of muon injection and the availability of his help whenever I need. I also like to thank my collaborators for the angular distribution experiment. They are Frank Chmely, Ver- non Hughes, Steve Kittell, Yunan Kuang, Bjorn Matthias, Hans-Jurgen Mundinger, Benwen Ni, Gisbert zu Putlitz, Reiner Schaefer, and Kim Woodle. This experiment would not have been possible without the effort and commitment of these co-workers. Special thanks goes to Bjorn Matthias ior many helpful remarks and discussion from the first stage of data analysis to reading this manuscript. Technical support from LAMPF staff was marvelous. Thanks goes to Jov Ivie, Chandra Pillai, Richard Werbeck, and the LAMPF staff. I appreciate the help of the staff at the data analysis center (DAC) of LAMPF; they are Art Chavez, John Faucett, Elvira Martinez, and Mike Oothoudt. -
Experimental Limits for the Electron-Proton Charge Difference and for the Neutron Charge
790 Session P 1 (II and III) polarized muons were stopped in argon Our recent measurements of the asymmetry para at different magnetic fields and for case I pions were meter, a, for various gases at high pressure, done in stopped. The solid curves were obtained from the a free muon precession experiment3), give : analysis of the data and represent the per cent am plitude of A compared to the total counting rate. The dashed curves are theoretical line shapes centered in each case at the muonium precession frequency predicted from the measured value of the magnetic field. Resonances are clearly seen in cases II and Since depolarization in this experiment is a necessary III and indicate abundant formation of muonium condition for muonium formation, it can be conclu in pure argon. ded that no more than one half of the muons stopping The general conditions required to form muonium in SF6 and 02 form muonium, whereas all of the and to retain its polarization are not well understood. muons may form muonium in A, N2, and N20. From our experiments alone it is not determined In view of the abundant formation of muonium in whether the high purity of the argon gas is required, pure argon, it should be possible to measure the although if they are combined with unpublished hyperfine structure, Av, of muonium with high preci negative results of others2) it appears that the purity sion. Comparison of a precise experimental value is essential. If this is indeed true, it seems quite for Av with the theoretical value would provide a likely that free muonium is lost in a chemical reac critical test of electrodynamics involving the muon tion in impure argon. -
Physics of Muonium and Muonium Oscillations
Physics of muonium and muonium oscillations Alexey A. Petrov1 1Department of Physics and Astronomy Wayne State University, Detroit, MI 48201, USA Precision studies of a muonium, the bound state of a muon and an electron, provide access to physics beyond the Standard Model. We propose that extensive theoretical and experimental studies of atomic physics of a muonium, its decays and muonium-antimuonium oscillations could provide an impact on indirect searches for new physics. An especially clean system to study BSM effects in in the Standard Model at tree level, New Physics degrees lepton sector is muonium Mµ, a QED bound state of a of freedom can effectively compete with the SM parti- positively-charged muon and a negatively-charged elec- cles running in the loop graphs, making their discovery + − tron, jMµi ≡ jµ e i. The main decay channel of the possible. This is, of course, only true provided beyond state is driven by the weak decay of the muon. The av- the Standard Model (BSM) constructions include flavor- erage lifetime of a muonium state τMµ is thus expected violating interactions. In order to probe those we con- to be the same as that of the muon, τµ = (2:1969811 ± sider muonium decays and oscillations. −6 0:0000022) × 10 s [1], apart from the tiny effect due to Denoting the \muon quantum number" by Lµ, FCNC 2 2 2 −10 time dilation, (τMµ −τµ)/τµ = α me=(2mµ) = 6×10 . decays of a muonium would probe ∆Lµ = 1 interactions. Such a lifetime, in principle, is rather long to allow for The effective Lagrangian, L∆Lµ=1, can then be divided precision measurements of muonium's atomic and parti- eff into the dipole part, LD, and a part that involves four- cle physics properties [2]. -
Femtosecond Laser-Assisted Electron Scattering for Ultrafast Dynamics of Atoms and Molecules
atoms Review Femtosecond Laser-Assisted Electron Scattering for Ultrafast Dynamics of Atoms and Molecules Reika Kanya and Kaoru Yamanouchi * Department of Chemistry, School of Science, The University of Tokyo, Tokyo 113-0033, Japan * Correspondence: [email protected]; Tel.: +81-3-5841-4334 Received: 7 July 2019; Accepted: 23 August 2019; Published: 2 September 2019 Abstract: The recent progress in experimental studies of laser-assisted electron scattering (LAES) induced by ultrashort intense laser fields is reviewed. After a brief survey of the theoretical backgrounds of the LAES process and earlier LAES experiments started in the 1970s, new concepts of optical gating and optical streaking for the LAES processes, which can be realized by LAES experiments using ultrashort intense laser pulses, are discussed. A new experimental setup designed for measurements of LAES induced by ultrashort intense laser fields is described. The experimental results of the energy spectra, angular distributions, and laser polarization dependence of the LAES signals are presented with the results of the numerical simulations. A light-dressing effect that appeared in the recorded LAES signals is also shown with the results of the numerical calculations. In addition, as applications of the LAES process, laser-assisted electron diffraction and THz-wave-assisted electron diffraction, both of which have been developed for the determination of instantaneous geometrical structure of molecules, are introduced. Keywords: electron scattering; electron diffraction; -
Study of Nuclear Properties with Muonic Atoms
EPJ manuscript No. (will be inserted by the editor) Study of nuclear properties with muonic atoms A. Knecht1a, A. Skawran1;2b, and S. M. Vogiatzi1;2c 1 Paul Scherrer Institut, Villigen, Switzerland 2 Institut f¨urTeilchen- und Astrophysik, ETH Z¨urich, Switzerland Received: date / Revised version: date Abstract. Muons are a fascinating probe to study nuclear properties. Muonic atoms can easily be formed by stopping negative muons inside a material. The muon is subsequently captured by the nucleus and, due to its much higher mass compared to the electron, orbits the nucleus at very small distances. During this atomic capture process the muon emits characteristic X-rays during its cascade down to the ground state. The energies of these X-rays reveal the muonic energy level scheme, from which properties like the nuclear charge radius or its quadrupole moment can be extracted. While almost all stable elements have been examined using muons, probing highly radioactive atoms has so far not been possible. The muX experiment has developed a technique based on transfer reaction inside a high pressure hydrogen/deuterium gas cell to examine targets available only in microgram quantities. PACS. 14.60. Ef Muons { 36.10.Dr Positronium, muonium, muonic atoms and molecules { 32.30.Rj X-ray spectra { 21.10.-k General and average properties of nuclei 1 Introduction Muons are fascinating particles with experiments being conducted in the context of particle, nuclear and atomic physics [1]. Additionally, also applied research is possible by measuring the spin precession and dynamics of muons inside materials through the µSR technique [2] thus probing the internal magnetic fields of the sample under study. -
Lecture 5 — Wave and Particle Beams
Lecture 5 — Wave and particle beams. 1 What can we learn from scattering experiments • The crystal structure, i.e., the position of the atoms in the crystal averaged over a large number of unit cells and over time. This information is extracted from Bragg diffraction. • The deviation from perfect periodicity. All real crystals have a finite size and all atoms are subject to thermal motion (at zero temperature, to zero-point motion). The general con- sequence of these deviations from perfect periodicity is that the scattering will no longer occur exactly at the RL points (δ functions), but will be “spread out”. Finite-size effects and fluctuations of the lattice parameters produce peak broadening without altering the integrated cross section (amount of “scattering power”) of the Bragg peaks. Fluctuation in the atomic positions (e.g., due to thermal motion) or in the scattering amplitude of the individual atomic sites (e.g., due to substitutions of one atomic species with another), give rise to a selective reduction of the intensity of certain Bragg peaks by the so-called Debye- Waller factor, and to the appearance of intensity elsewhere in reciprocal space (diffuse scattering). • The case of liquids and glasses. Here, crystalline order is absent, and so are Bragg diffraction peaks, so that all the scattering is “diffuse”. Nonetheless, scattering of X-rays and neutrons from liquids and glasses is exploited to extract radial distribution functions — in essence, the probability of finding a certain atomic species at a given distance from another species. • The magnetic structure. Neutron possess a dipole moment and are strongly affected by the presence of internal magnetic fields in the crystals, generated by the magnetic moments of unpaired electrons.