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Title: Nucleon Electromagnetic Form Factors

Although nucleons account for nearly all the visible mass in the universe, they have a complicated structure that is still incompletely understood. The first indication that nucleons have an internal structure, was the measurement of the proton magnetic moment by Frisch and Stern (1933) which revealed a large deviation from the value expected for a point-like Dirac particle. The investigation of the spatial structure of the nucleon, resulting in the first quantitative measurement of the proton charge radius, was initiated by the HEPL (Stanford) experiments in the 1950s, for which Hofstadter was awarded the 1961 Nobel prize. The first indication of a non-zero neutron charge distribution was obtained by scattering thermal neutrons off atomic electrons. The recent revival of its experimental study through the operational implementation of novel instrumentation has instigated a strong theoretical interest. Nucleon electro-magnetic form factors (EMFFs) are optimally studied through the exchange of a virtual photon, in elastic electron-nucleon scattering. The momentum transferred to the nucleon by the virtual photon can be selected to probe different scales of the nucleon, from integral properties such as the charge radius to scaling properties of its internal constituents. Polarization instrumentation, polarized beams and targets, and the measurement of themore » polarization of the recoiling nucleon have been essential in the accurate separation of the charge and magnetic form factors and in studies of the elusive neutron charge form factor.« less
Authors:
Publication Date:
OSTI Identifier:
834525
Report Number(s):
JLAB-PHY-04-300; DOE/ER/40150-2972
TRN: US0407237
DOE Contract Number:
AC05-84ER40150
Resource Type:
Conference
Resource Relation:
Conference: SUSSP58, St. Andrews, Scotland (GB), 08/30/2004--09/01/2004; Other Information: PBD: 1 Aug 2004
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (US)
Sponsoring Org:
USDOE Office of Energy Research (ER) (US)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CHARGE DISTRIBUTION; ELECTROMAGNETIC FORM FACTORS; ELECTRONS; FORM FACTORS; IMPLEMENTATION; MAGNETIC MOMENTS; NEUTRONS; NUCLEONS; PHOTONS; POLARIZATION; POLARIZED BEAMS; PROBES; PROTONS; SCATTERING; TARGETS; THERMAL NEUTRONS