Precision studies of the reaction 3 He(e,e ′ p) using the threespectrometer facility at the Mainz microtron MAMI are presented.All data are for quasielastic kinematics at | q | = 685 MeV/c.Absolute cross sections were measured at three electron kinematics.For the measured missing momenta range from 10 to 165 MeV/c, no strength is observed for missing energies higher than 20 MeV.Distorted momentum distributions were extracted for the two-body breakup and the continuum.The longitudinal and transverse behavior was studied by measuring the cross section for three photon polarizations.The longitudinal and transverse nature of the cross sections is well described by a currently accepted and widely used prescription of the off-shell electron-nucleon cross-section.The results are compared to modern three-body calculations and to previous data.
Transverse electron scattering form factors from the ground-state rotational band of $^{181}\mathrm{Ta}$ have been measured to study the single-particle contribution to the magnetization current density. The data are compared with a Hartree-Fock calculation by use of density matrix expansion with filling approximation.
Definitive evidence for strong density dependence in the two-nucleon effective interaction is noted in inelastic ($p$,${p}^{\ensuremath{'}}$) differential cross section and polarization data for ${E}_{p}\ensuremath{\sim}150$ MeV. These effects are quite sensitive to variations in the nuclear medium and are well described, for inelastic scattering, by the local-density approximation with use of density-dependent effective interactions from nuclear matter.
The first (e,e'p) polarization transfer measurements on a nucleus heavier than deuterium have been carried out at Jefferson Laboratory. Transverse and longitudinal components of the polarization of protons ejected in the reaction 16O(e,e'p) were measured in quasielastic perpendicular kinematics at a Q^2 of 0.8 (GeV/c)^2. The data are in good agreement with state of the art calculations, but do not exclude possible changes in the ratio of the electric to magnetic form factors of the nucleon in the nuclear medium at the level of recent theoretical predictions.
We report the first measurement of target single-spin asymmetries (A$_N$) in the inclusive hadron production reaction, $e~$+$~^3\text{He}^{\uparrow}\rightarrow h+X$, using a transversely polarized $^3$He target. The experiment was conducted at Jefferson Lab in Hall A using a 5.9-GeV electron beam. Three types of hadrons ($\pi^{\pm}$, $\text{K}^{\pm}$ and proton) were detected in the transverse hadron momentum range 0.54 $
The distribution of Gamow-Teller strength in the $^{18}\mathrm{O}(p, n)^{18}\mathrm{F}$ reaction was studied at a bombarding energy of 135 MeV. Five ${1}^{+}$, $T=0$ states are identified below ${E}_{x}=7$ MeV and a concentration of ${1}^{+}$ states of presumed $T=1$ character is observed between ${E}_{x}=9.5 \mathrm{and} 12$ MeV. Approximately 82% of the ${1}^{+}$ strength is concentrated into the ground-state transition and only 5.5% is seen in the $T=1$ component. Normalization of the ground-state transition to the known Gamow-Teller matrix element from the analogous beta decay of $^{18}\mathrm{Ne}$ allows the ($p, n$) cross sections to be related to the Gamow-Teller strength. The resulting total Gamow-Teller strength observed in the ($p, n$) reaction is about two-thirds of the minimum value required by the sum rule for a $T=1$ nucleus. This result is in reasonable agreement with the total Gamow-Teller strength predicted from a shell-model calculation which uses empirically renormalized single-particle Gamow-Teller matrix elements. The concentration of the $T=0$ strength predominantly into the ground state and the observed ratio of $T=1$ to $T=0$ strength also are consistent with these calculations.NUCLEAR REACTIONS $^{18}\mathrm{O}(p, n)^{18}\mathrm{F}$, $E=135$ MeV; neutron spectra measured in \ensuremath{\sim}3\ifmmode^\circ\else\textdegree\fi{} steps between 0\ifmmode^\circ\else\textdegree\fi{} and 69\ifmmode^\circ\else\textdegree\fi{}; angular distributions extracted for separate transitions. Strengths of forward-peaked transitions compared with shell-model predictions of Gamow-Teller strength.
