600 research outputs found
Short-Distance Structure of Nuclei
One of Jefferson Lab's original missions was to further our understanding of
the short-distance structure of nuclei. In particular, to understand what
happens when two or more nucleons within a nucleus have strongly overlapping
wave-functions; a phenomena commonly referred to as short-range correlations.
Herein, we review the results of the (e,e'), (e,e'p) and (e,e'pN) reactions
that have been used at Jefferson Lab to probe this short-distance structure as
well as provide an outlook for future experiments.Comment: 16 pages, 8 figures, for publication in Journal of Physics
Polarized light ions and spectator nucleon tagging at EIC
An Electron-Ion Collider (EIC) with suitable forward detection capabilities
would enable a unique experimental program of deep-inelastic scattering (DIS)
from polarized light nuclei (deuterium 2H, helium 3He) with spectator nucleon
tagging. Such measurements promise significant advances in several key areas of
nuclear physics and QCD: (a) neutron spin structure, by using polarized
deuterium and eliminating nuclear effects through on-shell extrapolation in the
spectator proton momentum; (b) quark/gluon structure of the bound nucleon at x
> 0.1 and the dynamical mechanisms acting on it, by measuring the spectator
momentum dependence of nuclear structure functions; (c) coherent effects in
QCD, by exploring shadowing in tagged DIS on deuterium at x << 0.1. The JLab
MEIC design (CM energy sqrt{s} = 15-50 GeV/nucleon, luminosity ~ 10^{34}
cm^{-2} s^{-1}) provides polarized deuterium beams and excellent coverage and
resolution for forward spectator tagging. We summarize the physics topics, the
detector and beam requirements for spectator tagging, and on-going R&D efforts.Comment: 6 pages, 2 figures. Prepared for proceedings of DIS 2014, XXII.
International Workshop on Deep-Inelastic Scattering and Related Subjects,
University of Warsaw, Poland, April 28 - May 2, 201
Precise determination of proton magnetic radius from electron scattering data
We extract the proton magnetic radius from the high-precision electron-proton
elastic scattering cross section data. Our theoretical framework combines
dispersion analysis and chiral effective field theory and implements the
dynamics governing the shape of the low- form factors. It allows us to use
data up to 0.5 GeV for constraining the radii and overcomes the
difficulties of empirical fits and extrapolation. We obtain
a magnetic radius = 0.850 0.001 (fit 68%) 0.010 (theory full
range) fm, significantly different from earlier results obtained from the same
data, and close to the extracted electric radius = 0.842 0.002
(fit) 0.010 (theory) fm.Comment: 5 pages, 2 figure
Electron Spin Precession at CEBAF
The nuclear physics experiments at the Thomas Jefferson National Accelerator
Facility often require longitudinally polarized electrons to be simultaneously
delivered to three experimental halls. The degree of longitudinal polarization
to each hall varies as function of the accelerator settings, making it
challenging in certain situations to deliver a high degree of longitudinal
polarization to all the halls simultaneously. Normally, the degree of
longitudinal polarization the halls receive is optimized by changing the
initial spin direction at the beginning of the machine with a Wien filter.
Herein, it is shown that it is possible to further improve the degree of
longitudinal polarization for multiple experimental halls by redistributing the
energy gain of the CEBAF linacs while keeping the total energy gain fixed.Comment: 4 pages, 3 figures, to appear in the proceedings of the 18th
International Symposium on Spin Physics (SPIN2008
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