164 research outputs found
Longitudinal-Transverse Separations of Structure Functions at Low for Hydrogen and Deuterium
We report on a study of the longitudinal to transverse cross section ratio,
, at low values of and , as determined from
inclusive inelastic electron-hydrogen and electron-deuterium scattering data
from Jefferson Lab Hall C spanning the four-momentum transfer range 0.06 GeV. Even at the lowest values of , remains
nearly constant and does not disappear with decreasing , as expected. We
find a nearly identical behaviour for hydrogen and deuterium.Comment: 4 pages, 2 gigure
Inclusive Electron-Nucleus Scattering at Large Momentum Transfer
Inclusive electron scattering is measured with 4.045 GeV incident beam energy
from C, Fe and Au targets. The measured energy transfers and angles correspond
to a kinematic range for Bjorken and momentum transfers from . When analyzed in terms of the y-scaling function the data show
for the first time an approach to scaling for values of the initial nucleon
momenta significantly greater than the nuclear matter Fermi-momentum (i.e. GeV/c).Comment: 5 pages TEX, 5 Postscript figures also available at
http://www.krl.caltech.edu/preprints/OAP.htm
Correlated Strength in Nuclear Spectral Function
We have carried out an (e,e'p) experiment at high momentum transfer and in
parallel kinematics to measure the strength of the nuclear spectral function
S(k,E) at high nucleon momenta k and large removal energies E. This strength is
related to the presence of short-range and tensor correlations, and was known
hitherto only indirectly and with considerable uncertainty from the lack of
strength in the independent-particle region. This experiment confirms by direct
measurement the correlated strength predicted by theory.Comment: 4 pages, 2 figures, accepted by Phys. Rev. Let
Probing Quark-Gluon Interactions with Transverse Polarized Scattering
We have extracted QCD matrix elements from our data on double polarized
inelastic scattering of electrons on nuclei. We find the higher twist matrix
element \tilde{d_2}, which arises strictly from quark- gluon interactions, to
be unambiguously non zero. The data also reveal an isospin dependence of higher
twist effects if we assume that the Burkhardt-Cottingham Sum rule is valid. The
fundamental Bjorken sum rule obtained from the a0 matrix element is satisfied
at our low momentum transfer.Comment: formerly "Nachtmann Moments of the Proton and Deuteron Spin Structure
Functions
Scaling of the F_2 structure function in nuclei and quark distributions at x>1
We present new data on electron scattering from a range of nuclei taken in
Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the
cross section for , which is sensitive to short range contributions to the
nuclear wave-function, and in deep inelastic scattering corresponds to probing
extremely high momentum quarks. This result agrees with higher energy muon
scattering measurements, but is in sharp contrast to neutrino scattering
measurements which suggested a dramatic enhancement in the distribution of the
`super-fast' quarks probed at x>1. The falloff at x>1 is noticeably stronger in
^2H and ^3He, but nearly identical for all heavier nuclei.Comment: 5 pages, 4 figures, to be submitted to physical revie
Proton G_E/G_M from beam-target asymmetry
The ratio of the proton's electric to magnetic form factor, G_E/G_M, can be
extracted in elastic electron-proton scattering by measuring either cross
sections, beam-target asymmetry or recoil polarization. Separate determinations
of G_E/G_M by cross sections and recoil polarization observables disagree for
Q^2 > 1 (GeV/c)^2. Measurement by a third technique might uncover an unknown
systematic error in either of the previous measurements. The beam-target
asymmetry has been measured for elastic electron-proton scattering at Q^2 =
1.51 (GeV/c)^2 for target spin orientation aligned perpendicular to the beam
momentum direction. This is the largest Q^2 at which G_E/G_M has been
determined by a beam-target asymmetry experiment. The result, \muG_E/G_M =
0.884 +/- 0.027 +/- 0.029, is compared to previous world data.Comment: 8 pages, 6 figures, Updated to be version published in Physical
Review
Proton Spin Structure in the Resonance Region
We have examined the spin structure of the proton in the region of the
nucleon resonances (1.085 GeV < W < 1.910 GeV) at an average four momentum
transfer of Q^2 = 1.3 GeV^2. Using the Jefferson Lab polarized electron beam, a
spectrometer, and a polarized solid target, we measured the asymmetries
A_parallel and A_perp to high precision, and extracted the asymmetries A_1 and
A_2, and the spin structure functions g_1 and g_2. We found a notably non-zero
A_perp, significant contributions from higher-twist effects, and only weak
support for polarized quark--hadron duality.Comment: 6 pages, 4 figures, REVTeX4, similar to PRL submission, plots
colorized and appenix added, v3: minor edit, matches PR
Measurements of electron-proton elastic cross sections for
We report on precision measurements of the elastic cross section for
electron-proton scattering performed in Hall C at Jefferson Lab. The
measurements were made at 28 unique kinematic settings covering a range in
momentum transfer of 0.4 5.5 . These measurements
represent a significant contribution to the world's cross section data set in
the range where a large discrepancy currently exists between the ratio of
electric to magnetic proton form factors extracted from previous cross section
measurements and that recently measured via polarization transfer in Hall A at
Jefferson Lab.Comment: 17 pages, 18 figures; text added, some figures replace
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