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

First measurements of the ^16O(e,e'pn)^14N reaction

This paper reports on the first measurement of the ^16O(e,e'pn)^14N reaction. Data were measured in kinematics centred on a super-parallel geometry at energy and momentum transfers of 215 MeV and 316 MeV/c. The experimental resolution was sufficient to distinguish groups of states in the residual nucleus but not good enough to separate individual states. The data show a strong dependence on missing momentum and this dependence appears to be different for two groups of states in the residual nucleus. Theoretical calculations of the reaction using the Pavia code do not reproduce the shape or the magnitude of the data.Comment: 10 pages, 11 figures, 2 tables, Accepted for publication in EPJ

A Measurement of the Electric Form Factor of the Neutron through d⃗(e⃗,e′n)p\vec{d}(\vec{e},e'n)p at Q2=0.5Q^2 = 0.5 (GeV/c)2^2

We report the first measurement of the neutron electric form factor $G_E^n$ via $\vec{d}(\vec{e},e'n)p$ using a solid polarized target. $G_E^n$ was determined from the beam-target asymmetry in the scattering of longitudinally polarized electrons from polarized deuterated ammonia, $^{15}$ND$_3$. The measurement was performed in Hall C at Thomas Jefferson National Accelerator Facility (TJNAF) in quasi free kinematics with the target polarization perpendicular to the momentum transfer. The electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle segmented detector. We find $G_E^n = 0.04632\pm0.00616 (stat.) \pm0.00341 (syst.)$ at $Q^2 = 0.495$ (GeV/c)$^2$.Comment: Latex2e 5 pages, 3 figure

Measurements of electron-proton elastic cross sections for 0.4<Q2<5.5(GeV/c)20.4 < Q^2 < 5.5 (GeV/c)^2

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 $<$ $Q^2$ $<$ 5.5 $(\rm GeV/c)^2$. These measurements represent a significant contribution to the world's cross section data set in the $Q^2$ 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

Longitudinal-Transverse Separations of Structure Functions at Low Q2Q^{2} for Hydrogen and Deuterium

We report on a study of the longitudinal to transverse cross section ratio, $R=\sigma_L/\sigma_T$, at low values of $x$ and $Q^{2}$, 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 $< Q^{2} < 2.8$ GeV$^{2}$. Even at the lowest values of $Q^{2}$, $R$ remains nearly constant and does not disappear with decreasing $Q^{2}$, as expected. We find a nearly identical behaviour for hydrogen and deuterium.Comment: 4 pages, 2 gigure

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 $x>1$, 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

Cross Section Measurement of Charged Pion Photoproduction from Hydrogen and Deuterium

We have measured the differential cross section for the gamma n --> pi- p and gamma p --> pi+ n reactions at center of mass angle of 90 degree in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at photon energies greater than 3.3 GeV exhibit a global scaling behavior for both pi- and pi+ photoproduction, consistent with the constituent counting rule and the existing pi+ photoproduction data. Possible oscillations around the scaling value are suggested by these new data The data show enhancement in the scaled cross section at a center-of-mass energy near 2.2 GeV. The cross section ratio of exclusive pi- to pi+ photoproduction at high energy is consistent with the prediction based on one-hard-gluon-exchange diagrams

New measurements of high-momentum nucleons and short-range structures in nuclei

We present new measurements of electron scattering from high-momentum nucleons in nuclei. These data allow an improved determination of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data also include the kinematic region where three-nucleon correlations are expected to dominate.Comment: 5 pages, 3 figures. Results from JLab E02-01