377 research outputs found
Dispersion strenghthening of metals Progress report, Sep. 1965 - Feb. 1966
Apparatus constructed for controlled oxidation of iron-beryllium alloy powder
Book Reviews
THE SILVERLAKE EXPERIMENT. By Lamar T. Empey and Steven G. Lubeck. Chicago: Aldine Publishing Company, 1971. Pp. x, 354. 10.00.
THE INTERNATIONAL LAW OF CIVIL WAR. Edited by Richard A. Falk. Baltimore: The Johns Hopkins Press, 1971. Pp. xix, 452. 6.95
Phenomenology of the Deuteron Electromagnetic Form Factors
A rigorous extraction of the deuteron charge form factors from tensor
polarization data in elastic electron-deuteron scattering, at given values of
the 4-momentum transfer, is presented. Then the world data for elastic
electron-deuteron scattering is used to parameterize, in three different ways,
the three electromagnetic form factors of the deuteron in the 4-momentum
transfer range 0-7 fm^-1. This procedure is made possible with the advent of
recent polarization measurements. The parameterizations allow a
phenomenological characterization of the deuteron electromagnetic structure.
They can be used to remove ambiguities in the form factors extraction from
future polarization data.Comment: 18 pages (LaTeX), 2 figures Feb. 25: minor changes of content and in
Table
New Measurement of Parity Violation in Elastic Electron-Proton Scattering and Implications for Strange Form Factors
We have measured the parity-violating electroweak asymmetry in the elastic
scattering of polarized electrons from the proton. The result is A = -15.05 +-
0.98(stat) +- 0.56(syst) ppm at the kinematic point theta_lab = 12.3 degrees
and Q^2 = 0.477 (GeV/c)^2. The measurement implies that the value for the
strange form factor (G_E^s + 0.392 G_M^s) = 0.025 +- 0.020 +- 0.014, where the
first error is experimental and the second arises from the uncertainties in
electromagnetic form factors. This measurement is the first fixed-target parity
violation experiment that used either a `strained' GaAs photocathode to produce
highly polarized electrons or a Compton polarimeter to continuously monitor the
electron beam polarization.Comment: 8 pages, 4 figures, Tex, elsart.cls; revised version as accepted for
Phys. Lett.
Measurement of Tensor Polarization in Elastic Electron-Deuteron Scattering at Large Momentum Transfer
Tensor polarization observables (t20, t21 and t22) have been measured in
elastic electron-deuteron scattering for six values of momentum transfer
between 0.66 and 1.7 (GeV/c)^2. The experiment was performed at the Jefferson
Laboratory in Hall C using the electron HMS Spectrometer, a specially designed
deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new
data determine to much larger Q^2 the deuteron charge form factors G_C and G_Q.
They are in good agreement with relativistic calculations and disagree with
pQCD predictions.Comment: 5 pages, 4 figures, for associated informations, see
http://isnwww.in2p3.fr/hadrons/t20/t20_ang.html clarification about several
topics, one figure has been had, extraction of form factors use AQ
interpolation in our Q2 range onl
A precise measurement of the deuteron elastic structure function A(Q^2)
The A(Q^2) structure function in elastic electron-deuteron scattering was
measured at six momentum transfers Q^2 between 0.66 and 1.80 (GeV/c)^2 in Hall
C at Jefferson Laboratory. The scattered electrons and recoil deuterons were
detected in coincidence, at a fixed deuteron angle of 60.5 degrees. These new
precise measurements resolve discrepancies between older sets of data. They put
significant constraints on existing models of the deuteron electromagnetic
structure, and on the strength of isoscalar meson exchange currents.Comment: 3 LaTeX pages plus 2 PS figure
The ratio of proton's electric to magnetic form factors measured by polarization transfer
The ratio of the proton's elastic electromagnetic form factors was obtained
by measuring the transverse and longitudinal polarizations of recoiling protons
from the elastic scattering of polarized electrons with unpolarized protons.
The ratio of the electric to magnetic form factor is proportional to the ratio
of the transverse to longitudinal recoil polarizations. The ratio was measured
over a range of four-momentum transfer squared between 0.5 and 3.5 GeV-squared.
Simultaneous measurement of transverse and longitudinal polarizations in a
polarimeter provides good control of the systematic uncertainty. The results
for the ratio of the proton's electric to magnetic form factors show a
systematic decrease with increasing four momentum squared, indicating for the
first time a marked difference in the spatial distribution of charge and
magnetization currents in the proton.Comment: 5 pages, 2 figures, version of paper after corrections due to
referees comments and shortened by removing one figure for Physical Review
Letter
Virtual Compton Scattering and the Generalized Polarizabilities of the Proton at Q^2=0.92 and 1.76 GeV^2
Virtual Compton Scattering (VCS) on the proton has been studied at Jefferson
Lab using the exclusive photon electroproduction reaction (e p --> e p gamma).
This paper gives a detailed account of the analysis which has led to the
determination of the structure functions P_LL-P_TT/epsilon and P_LT, and the
electric and magnetic generalized polarizabilities (GPs) alpha_E(Q^2) and
beta_M(Q^2) at values of the four-momentum transfer squared Q^2= 0.92 and 1.76
GeV^2. These data, together with the results of VCS experiments at lower
momenta, help building a coherent picture of the electric and magnetic GPs of
the proton over the full measured Q^2-range, and point to their non-trivial
behavior.Comment: version 2: modified according to PRC Editor's and Referee's
recommendations. Archival paper for the E93-050 experiment at JLab Hall A. 28
pages, 23 figures, 5 cross-section tables. To be submitted to Phys.Rev.
Virtual Compton Scattering and Neutral Pion Electroproduction in the Resonance Region up to the Deep Inelastic Region at Backward Angles
We have made the first measurements of the virtual Compton scattering (VCS)
process via the H exclusive reaction in the nucleon resonance
region, at backward angles. Results are presented for the -dependence at
fixed GeV, and for the -dependence at fixed near 1.5 GeV.
The VCS data show resonant structures in the first and second resonance
regions. The observed -dependence is smooth. The measured ratio of
H to H cross sections emphasizes the different
sensitivity of these two reactions to the various nucleon resonances. Finally,
when compared to Real Compton Scattering (RCS) at high energy and large angles,
our VCS data at the highest (1.8-1.9 GeV) show a striking -
independence, which may suggest a transition to a perturbative scattering
mechanism at the quark level.Comment: 20 pages, 8 figures. To appear in Phys.Rev.
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