Search

We measured the ${}^{12}\mathrm{C}{(e,e}^{\ensuremath{'}}p)$ cross section as a function of missing energy in parallel kinematics for $(q,\ensuremath{\omega})=(970 \mathrm{MeV}/c, 330 \mathrm{MeV})$ and $(990 \mathrm{MeV}/c, 475 \mathrm{MeV}).$ At $\ensuremath{\omega}=475 \mathrm{MeV},$ at the maximum of the quasielastic peak, there is a large continuum ${(E}_{m}g50 \mathrm{MeV})$ cross section extending out to the deepest missing energy measured, amounting to almost 50% of the measured cross section. The ratio of data to distorted-wave impulse approximation (DWIA) calculation is 0.4 for both p and s shells. At $\ensuremath{\omega}=330 \mathrm{MeV},$ well below the maximum of the quasielastic peak, the continuum cross section is much smaller and the ratio of data to DWIA calculation is 0.85 for the p shell and 1.0 for the s shell. We infer that one or more mechanisms that increase with $\ensuremath{\omega}$ transform some of the single-nucleon knockouts into a multinucleon knockout, decreasing the valence knockout cross section and increasing the continuum cross section.

Elastic electron scattering cross sections have been measured for [sup 89]Y at 180[degree] for 0.72[lt][ital q][lt]2.67 fm[sup [minus]1]. The [ital M]1 form factor has been extracted and a Fourier-Bessel analysis performed to obtain the ground-state magnetization density. Calculations including effects of core polarization have been performed within the framework of the finite Fermi system theory. These show a weakening of the strong repulsion in the spin-isospin channel and are in overall agreement with the data.

We have measured the [sup 12]C([gamma][sup *],[pi][sup [minus]][ital p])[sup 11]C[sub g.s.] cross section using virtual bremsstrahlung at three points at invariant masses of 1444 and 1530 MeV. At low neutron initial momentum ([ital p][sub [ital m]][approx]60 MeV/[ital c]) and large [ital N][sup *] momentum ([ital p][sub [ital N]][sup *][approx]750 MeV/[ital c]) the measured cross section is at or below the distorted wave impulse approximation (DWIA) calculation. At larger initial momentum ([ital p][sub [ital m]][approx]220 MeV/[ital c]) and smaller [ital N][sup *] momentum ([ital p][sub [ital N]][sup *][approx]500 MeV/[ital c]), the measured cross section is almost twice as large as the DWIA calculation. This discrepancy might be due to [ital N][sup *]-nucleus interactions.

Inelastic electron scattering cross sections have been measured from high spin transitions in {sup 208}Pb. Measurements were made over a range of momentum transfer of 1.1 to 2.9 fm{sup {minus}1} with energy resolution between 14 and 22 keV. In addition to the previously measured 14{sup {minus}}, 12{sup {minus}}, and 12{sup +} levels, electron scattering cross sections have been measured on {ital M}11, {ital M}10, {ital M}9, {ital E}9, and {ital E}7 transitions. High spin states are quenched from the predicted Woods-Saxon single particle amplitudes by 22% to 67%. Evidence is presented for the fragmentation of the 7.06 MeV 12{sup {minus}} transition strength. Results are interpreted in terms of the independent particle model.

Differential cross sections for inelastic scattering from $^{142}\mathrm{Ce}$ have been measured for excitation energies less than 3.3 MeV over a range of momentum transfer of 0.4 to 2.5 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$. The data have been analyzed to extract transition charge densities. These densities are interpreted in terms of a quasiparticle-phonon approach and finite Fermi system theory to disentangle the collective and noncollective modes of excitation.

Electron-scattering cross sections, measured between 0.4 and 3.1 fm{sup {minus}1}, have been unfolded to obtain charge transition densities for the low-lying 2{sup +}, 4{sup +}, 6{sup +}, and 8{sup +} states in {sup 86}Sr. A comparison is made to analogous levels in {sup 92}Mo. Angular momentum recoupling in the 1{ital g}{sub 9/2} shell of two protons in {sup 92}Mo and two neutron holes in {sup 86}Sr are the dominant configurations for these levels. Proton core polarization in {sup 86}Sr neutron valence transitions diminishes with increasing multipolarity, indicating the residual interaction weakens with increasing momentum transfer.

Inelastic-electron-scattering cross sections have been measured for the first three excitations in $^{89}\mathrm{Y}$ at forward angles for momentum transfers of 1.25q3.01 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$ and at 180\ifmmode^\circ\else\textdegree\fi{} for 0.72q2.67 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$. Transition charge and current densities extracted in a Fourier-Bessel analysis of all existing cross sections show considerable departures from the single-particle model. The inclusion of core polarization from the operator renormalization approximation for shell models gives good agreement with experimental results.

We have measured missing-energy spectra for the reaction {sup 12}C({ital e},{ital e}{prime}{ital p}) in the quasielastic region in parallel kinematics at momentum transfers {ital q} of 585, 775, and 827 MeV/{ital c}. We observed {sup 1}{ital p} and {sup 1}{ital s} single-proton knockout peaks and large broad strength attributed to multinucleon knockout. We saw no increase in strength at pion threshold. The ratio of single-particle knockout to a distorted-wave impulse-approximation calculation is approximately constant with {ital q}. Multinucleon knockout is 25%--40% of the total cross section; it increases with {ital q}. This quasielastic non-single-nucleon knockout is much stronger than previously observed.

Inelastic-electron-scattering cross sections for /sup 56/Fe have been measured in the continuum region. The longitudinal and transverse inelastic response functions have been determined for vector momentum transfers, q, from 210--410 MeV/c and for energy losses 0

A study of the ..pi..1g/sub 9/2/ orbit size in /sup 88/Sr, /sup 90/Zr, and /sup 92/Mo is presented. The rms radius for the point-proton density is extracted by studying transitions to 8/sup +/ states in these nuclei. The radii are consistently larger than a value determined in a magnetic electron scattering experiment on /sup 93/Nb. A qualitative discussion of the ground state occupation of the ..pi..1g/sub 9/2/ orbit based on the transition amplitudes to the 8/sup +/ states is given.

Inelastic electron scattering from $^{48}\mathrm{Ca}$ has been performed over a momentum transfer range from 0.6 to 3.0 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$ in both forward and backward directions. Form factors have been obtained for 25 levels up to 10 MeV excitation. Charge and current densities for 11 low lying electric transitions and current densities for two magnetic transitions have been reconstructed in Fourier Bessel analysis. Three high spin states observed in the region of 9 MeV excitation are found to have the dominant configuration \ensuremath{\nu}(1${g}_{9/2}$,1${f}_{7/2}^{\mathrm{\ensuremath{-}}1}$${)}_{8}$ $^{\mathrm{\ensuremath{-}}}$ but with a total strength of only 36% predicted for the first ${8}^{\mathrm{\ensuremath{-}}}$ in a random-phase-approximation calculation. This is interpreted as evidence for particle-phonon coupling. Comparisons of the extracted densities are made with random-phase-approximation calculations using a zero-range, density-dependent Migdal interaction.

The ground-state magnetization densities of $^{207}\mathrm{Pb}$ and $^{205}\mathrm{Tl}$ have been studied by 180\ifmmode^\circ\else\textdegree\fi{} elastic electron scattering. The magnetic form factors were found to be quenched substantially relative to the predictions of the independent-particle model. Microscopic calculations indicate that core polarization can account for part of the observed suppression but it is not sufficient to reproduce the data. The quenching observed at high momentum transfers is comparable to that observed in related electron-scattering studies in the lead region, and can be explained in terms of partial occupancy of shell orbits in $^{208}\mathrm{Pb}$.

High resolution inelastic electron scattering measurements on /sup 140/Ce have led to the identification of a J/sup ..pi../ = 12/sup -/ state at 6.31 MeV. This transition has only 8% of the calculated single-particle strength. The absence of strong transverse excitations is interpreted as evidence for fragmentation of the single-particle strength.