We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the ...four-momentum transfer range 0.2 < Q^2 < 5.5 GeV^2. The data have been used to accurately perform 167 Rosenbluth-type longitudinal / transverse separations. The precision R = sigma_L / sigma_T data are presented here, along with the first separate values of the inelastic structure functions F_1 and F_L in this regime. The resonance longitudinal component is found to be significant, both in magnitude and in the existence of defined mass peaks. Additionally, quark-hadron duality is here observed above Q^2 = 1 GeV^2 in the separated structure functions independently.
Kaon electroproduction from light nuclei and hydrogen, using 1H, 2H, 3He, 4He, and Carbon targets has been measured at Jefferson Laboratory. The quasifree angular distributions of Lambda and Sigma ...hyperons were determined at Q^2= 0.35(GeV/c)^2 and W= 1.91GeV. Electroproduction on hydrogen was measured at the same kinematics for reference.
The quasielastic (e,eprimep) reaction was studied on targets of deuterium, carbon, and iron up to a value of momentum transfer Q2 of 8.1 (GeV/c)2. A nuclear transparency was determined by comparing ...the data to calculations in the plane-wave impulse approximation. The dependence of the nuclear transparency on Q2 and the mass number A was investigated in a search for the onset of the color transparency phenomenon. We find no evidence for the onset of color transparency within our range of Q2. A fit to the world's nuclear transparency data reflects the energy dependence of the free-proton-nucleon cross section.
Phys.Rev.C72:054602,2005 We studied the reaction 12C(e,e'p) in quasielastic kinematics at momentum
transfers between 0.6 and 1.8 (GeV/c)^2 covering the single-particle region.
From this the nuclear ...transparency factors are extracted using two methods.
The results are compared to theoretical predictions obtained using a
generalization of Glauber theory described in this paper. Furthermore, the
momentum distribution in the region of the 1s-state up to momenta of 300 MeV/c
is obtained from the data and compared to the Correlated Basis Function theory
and the Independent-Particle Shell model.
Phys.Rev.Lett.93:182501,2004 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.
Phys.Rev.C73:044607,2006 A pioneering experiment in Lambda hypernuclear spectroscopy, undertaken at
the Thomas Jefferson National Accelerator Facility (Jlab), was recently
reported. The experiment ...used the high- precision, continuous electron beam at
Jlab, and a special arrangement of spectrometer magnets to measure the spectrum
from {nat}C and 7Li targets using the (e,e' K+)reaction. The 12B hypernuclear
spectrum was previously published. This experiment is now reported in more
detail, with improved results for the 12B hypernuclear spectrum. In addition,
unpublished results of the 7He hypernuclear spectrum are also shown. This later
spectrum indicates the need for a more detailed few-body calculation of the
hypernucleus and the reaction process. The success of this experiment
demonstrates that the (e,e'K+) reaction can be effectively used as a high
resolution tool to study hypernuclear spectra, ant its use should be vigorously
pursued.
PDF
