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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.

Centre National de la Recherche Scientifique (France), Commissariat a l'Energie Atomique (France), National Science Foundation, Swiss National Science Foundation, K.C. Wong Foundation

Isoscalar spin-transfer excitations have been measured in ${}^{90}\mathrm{Zr}$ and ${}^{208}\mathrm{Pb}$ by inelastic scattering of vector and tensor polarized 400 MeV deuterons in an excitation energy range from 2.5 to 43 MeV and 2.3 to 23 MeV, respectively. For ${}^{90}\mathrm{Zr},$ spin excitations were found between 7.5 and 10.7 MeV and in a large structure in the continuum (18 to 28 MeV). For ${}^{208}\mathrm{Pb},$ spin excitations were found at 3.55 and 5.85 MeV, between 6.5 and 11 MeV, and spread over the continuum. Elastic scattering cross sections and vector and tensor analyzing powers were measured between 3.4 and $24\ifmmode^\circ\else\textdegree\fi{}$ for Zr and Pb, and optical potential parameters were derived. The experimental results are compared to DWIA/RPA calculations. The transition densities used are generated using the continuum random phase approximation.

The analyzing power A{sub y0} of the reaction H({rvec p},d){pi}{sup +} has been measured at a fixed value of the Mandelstam variable u{sub d}={minus}0.17GeV{sup 2} for nine proton energies between 1000 and 1300 MeV. The experiment was performed at SATURNE with the SPES1 spectrometer. The data exhibit structure around {radical} (s) {approx_equal}2.37GeV. The origin of this structure could be related to a resonancelike behavior of the {sup 1}S{sub 0}P or {sup 1}G{sub 4}F partial amplitudes. {copyright} {ital 1998} {ital The American Physical Society}

The first ({ital p},{ital n}) polarization-transfer measurements for delta production on a nuclear target are presented for the {sup 12}C({ital p}{searrow},{ital n}{searrow}) reaction at 0{degree} and 795 MeV. Polarization observables are used to extract the spin-longitudinal, spin-transverse, and spin-independent partial cross sections. In the spin-longitudinal channel, fair agreement is found between experiment and a model which includes a strongly attractive residual interaction. A large unexpected enhancement in the spin-transverse cross section is observed. {copyright} {ital 1996 The American Physical Society.}

The cross-section and analyzing power data for the inelastic scattering of polarized protons to the first ${2}^{+}$ and ${4}^{+}$ states of $^{12}\mathrm{C}$ between 200 MeV and 800 MeV have been analyzed through relativistic Dirac coupled channels calculations. Although considerably better agreement with the data has been obtained compared to previous nonrelativistic Schr\"odinger calculations, no better determination of the deformation parameters could be obtained. Deformations (both quadrupole and hexadecapole) are almost unchanged over this energy interval and agree with previous results.

The isoscalar spin strength in $^{12}\mathrm{C}$ has been studied in the inelastic scattering of polarized 400 MeV deuterons. The measurements were carried out over an angular range from 3\ifmmode^\circ\else\textdegree\fi{} to 7\ifmmode^\circ\else\textdegree\fi{} and an excitation energy range from 11 to 58 MeV (momentum transfer range from 0.34 to 0.92 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$). Previously unknown spin excitations were found in the 20-MeV region and over a broad range in the continuum with a cluster of strength around 30 MeV. The results are compared with spin-flip probability measurements in proton scattering. Below 35 MeV of excitation energy, the isoscalar relative spin response is strongly enhanced above the noninteracting Fermi gas value of 0.5. Above 35 MeV of excitation the spin response drops below 0.5.

We report on the first measurement of tensor polarization transfer coefficients for the excitation of the 12.7 MeV 1[sup +] state of [sup 12]C by ([ital [rvec d]],[ital [rvec d]]) inelastic scattering at 393 MeV. The experiment has been performed at Saturne with a tensor polarimeter. The data have allowed the determination of the spin-flip probability [ital S][sub 1], found to be in good agreement with the approximate signature [ital S][sub [ital d]][sup [ital y]] determined previously with a vector polarimeter. The relationships between measured polarizations and analyzing powers are discussed.

Differential cross sections and analyzing powers have been measured for inelastic proton excitation of states in $^{12}\mathrm{C}$ up to an excitation energy of 20 MeV. Angular distributions are reported for incoming proton energies of 200, 318, 398, 597, 698, and 800 MeV, typically over the momentum transfer range from 0.5 to 2 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$; some of these data have been published previously. Reaction calculations in the distorted-wave impulse approximation have been carried out for most of the data. Agreement between theory and experiment for both the magnitudes and shapes of the cross-section data is generally good; the analyzing-power distributions are less well described.

Angular distributions of the double-differential cross section ${\mathit{d}}^{2}$\ensuremath{\sigma}/d\ensuremath{\Omega} dE (\ensuremath{\sigma}) and the spin-flip probability ${\mathit{S}}_{\mathit{n}\mathit{n}}$ have been measured for inclusive inelastic proton scattering from $^{12}\mathrm{C}$ at ${\mathit{E}}_{\mathit{p}}$=318 MeV. Data have been obtained over an excitation energy range 9 MeV \ensuremath{\le}${\mathit{E}}_{\mathit{x}}$\ensuremath{\le}42 MeV for laboratory scattering angles of 3\ifmmode^\circ\else\textdegree\fi{}, 5\ifmmode^\circ\else\textdegree\fi{}, 7\ifmmode^\circ\else\textdegree\fi{}, 9\ifmmode^\circ\else\textdegree\fi{}, 12\ifmmode^\circ\else\textdegree\fi{}, 15\ifmmode^\circ\else\textdegree\fi{}, and 18\ifmmode^\circ\else\textdegree\fi{}. Multipole decompositions of angular distributions of both the spin-flip cross section ${\mathrm{\ensuremath{\sigma}}}_{\mathrm{SF}}$=\ensuremath{\sigma}${\mathit{S}}_{\mathit{n}\mathit{n}}$ and the estimated cross section for \ensuremath{\Delta}S=0 transitions have been performed. The distribution of deduced \ensuremath{\Delta}L=1, \ensuremath{\Delta}S=0 (the giant-dipole resonance) strength peaks near ${\mathit{E}}_{\mathit{x}}$=22 MeV; although there is apparently much more strength relative to the energy-weighted sum rule (EWSR) than expected, this appears to be an artifact of instrumental background at small angles. Approximately 55% of the EWSR for \ensuremath{\Delta}L=2, \ensuremath{\Delta}S=0 was observed spread uniformly across the spectrum with no evidence for a giant-quadrupole resonance. Angular distributions for ${\mathrm{\ensuremath{\sigma}}}_{\mathrm{SF}}$ were analyzed using the predictions from random-phase approximation calculations for the nuclear structure and distorted-wave impulse approximation calculations for the scattering. These predictions are found to provide a good description of the ${\mathrm{\ensuremath{\sigma}}}_{\mathrm{SF}}$ data above ${\mathit{E}}_{\mathit{x}}$=25 MeV; values of ${\mathit{S}}_{\mathit{n}\mathit{n}}$ are predicted somewhat too low in this region.

A complete set of diagonal spin-transfer observables has been measured at excitation energies between 30 and 40 MeV for inelastic proton scattering from $^{40}\mathrm{Ca}$ at 497 and 581 MeV at a momentum transfer of 0.56 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$. The longitudinal and transverse spin-flip probabilities are deduced. Their unequal enhancements relative to free nucleon-nucleon scattering values are explained by a distorted-wave impulse approximation calculation in which the finite nucleus random-phase approximation is used to describe the nuclear respose.

A signature {ital S}{sub {ital d}}{sup {ital y}} of isoscalar spin-transfer strength has been tested in the inelastic scattering of 400 MeV dueterons from {sup 12}C. It was then applied to the study of {sup 40}Ca over an angular range from 3{degree} to 7{degree} (momentum transfer range from 0.26 to 0.8 fm{sup {minus}1}) and an excitation energy range from 6.25 to 42 MeV. This is the first study of isoscalar spin strength in the continuum. Spin excitations were found in the 9 MeV region, and over a broad range in the continuum with a cluster strength around 15 MeV. The results are compared with spin-flip probability measurements in proton scattering. In contrast to the total relative spin response, which is strongly enhanced at high excitation, the isoscalar relative spin response is roughly consistent with noninteracting Fermi gas values.

Angular distributions of the double-differential cross section {ital d}{sup 2}{sigma}/{ital d}{Omega} {ital dE}({sigma}) and the spin-flip probability {ital S}{sub {ital n}{ital n}} have been measured for inclusive proton inelastic scattering from {sup 44}Ca at 290 MeV and from {sup 48}Ca at 318 MeV. Excitation energies up to about 50 MeV for {sup 44}Ca and 40 MeV for {sup 48}Ca have been investigated over the laboratory angular ranges of 3{degree} to 12{degree} for {sup 44}Ca and 3{degree} to 9{degree} for {sup 48}Ca. Multipole decompositions of angular distributions of both the spin-flip cross section {sigma}{ital S}{sub {ital n}{ital n}} and the estimated cross section for {Delta}{ital S}=0 transitions have been performed. Distributions of strengths were deduced for {Delta}{ital L}=1, {Delta}{ital S}=0 (the giant dipole), {Delta}{ital L}=2, {Delta}{ital S}=0 (the giant quadrupole), {Delta}{ital L}=0, {Delta}{ital S}=1 (the magnetic dipole), {Delta}{ital L}=1, {Delta}{ital S}=1 (the spin dipole), and {Delta}{ital L}=2, {Delta}{ital S}=1 (the spin quadrupole). The {Delta}{ital S}=0 summed strengths for {sup 44}Ca are lower than for {sup 40}Ca and {sup 48}Ca. The spin-dipole summed strengths are found to be approximately independent of {ital A}. For {sup 48}Ca, essentially all {ital M}1 strength observed was in the 10.23 MeV 1{sup +} state; for {supmore » 44}Ca, {ital M}1 strength was observed to be fragmented over a range of 7 to 18 Mev.« less

Analyzing power {ital A}{sub {ital y}} and spin-transfer observables {ital D}{sub {ital i}{ital j}} have been measured for 500-MeV proton inelastic scattering from {sup 28}Si. Measured values of the {ital D}{sub {ital i}{ital j}} for the 9.70-MeV 5{sup {minus}}, {ital T}=0, the 11.58-MeV 6{sup {minus}}, {ital T}=0, and the 14.35-MeV 6{sup {minus}}, {ital T}=1 states are reported at 17{degree} and 22{degree}; values of {ital A}{sub {ital y}} cover the range from about 10{degree} to 26{degree}. Nonrelativistic (NRIA) and relativistic (RIA) impulse-approximation calculations are compared with the data. The differences between the two types of calculations are generally small. The RIA yields excellent agreement with the {ital D}{sub {ital i}{ital j}} data for the 5{sup {minus}} state, and both RIA and NRIA do well for {ital D}{sub {ital i}{ital j}} data for the 6{sup {minus}}, {ital T}=0 state but poorly for the 6{sup {minus}}, {ital T}=1 state. For the {ital A}{sub {ital y}} data, both types of calculation give fairly good predictions for the 5{sup {minus}} and 6{sup {minus}}, {ital T}=1 states, but not for the 6{sup {minus}}, {ital T}=0 state. Comparison between theory and experiment for the combinations of observables {ital D}{sub {ital K}}, which are sensitive to individual termsmore » in the nucleon-nucleon interaction, indicates a possible need for medium corrections in the {ital T}=1 tensor and spin-orbit forces.« less

Cross sections, analyzing powers and spin-flip probabilities have been measured for inclusive inelastic scattering of 290 MeV protons from $^{54}\mathrm{Fe}$ at laboratory angles between 3.1\ifmmode^\circ\else\textdegree\fi{} and 20\ifmmode^\circ\else\textdegree\fi{}. The momentum transfers vary from small values (q\ensuremath{\sim}0.2 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$) where individual giant resonances of low multipolarity are observed, to larger values (q\ensuremath{\sim}1.4 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$) where quasielastic scattering dominates. Complete measurements of spin observables at 20\ifmmode^\circ\else\textdegree\fi{} are discussed, which show that present impulse approximation models based on either the Dirac or the Schr\"odinger equation for the nucleon are not capable of reproducing all the data. At all momentum and energy transfers the measured analyzing powers ${\mathit{A}}_{\mathit{y}}$ are smaller than predictions from nonrelativistic calculations. Relativistic calculations explain this reduction of ${\mathit{A}}_{\mathit{y}}$ for data near the quasielastic point (\ensuremath{\omega}=${\mathit{q}}^{2}$/2m) as an effect of the attractive scalar field in the nuclear medium; however, they fail to reproduce the observed slopes [d(${\mathit{A}}_{\mathit{y}}$)/d\ensuremath{\omega} at fixed angle], assuming for the nuclear response a simple Fermi gas model.

We present experimental results of the first high-precision test of quark-hadron duality in the spin-structure function g_1 of the neutron and $^3$He using a polarized 3He target in the four-momentum-transfer-squared range from 0.7 to 4.0 (GeV/c)^2. Global duality is observed for the spin-structure function g_1 down to at least Q^2 = 1.8 (GeV/c)^2 in both targets. We have also formed the photon-nucleon asymmetry A_1 in the resonance region for 3He and found no strong Q^2-dependence above 2.2 (GeV/c)^2., Comment: 13 pages, 3 figures

Doubly differential cross sections and spin-flip probabilities have been measured for 800-MeV proton scattering on {sup 40}Ca at 3.2{degree}, 4{degree}, 5{degree}, and 7{degree} in the laboratory, for excitation energies up to 45 MeV. The features of these observables in the continuum are discussed. The data indicate that nuclear spin excitations are enhanced at high excitation energy for angles corresponding to momentum transfers around 100 MeV/{ital c}, as previously observed for incident energies around 300 MeV. The relative nuclear spin response derived from these data is roughly independent of energy. This suggests that the dominance of spin-transfer excitation at high excitation energies for momentum transfers around 100 MeV/{ital c} is an intrinsic feature of the nuclear structure of {sup 40}Ca.

Analyzing powers have been measured for elastic and inelastic scattering of 500-MeV protons from $^{28}\mathrm{Si}$. These data for the first ${0}^{+}$, ${2}^{+}$, and ${4}^{+}$ states and the corresponding cross-section data have been analyzed with both Schr\"odinger and Dirac equation phenomenological coupled-channels methods. Good, qualitatively similar, results are achieved with the two methods.

We have measured the transverse asymmetry A{sub T{sup '}} in the quasielastic {sup 3}He-vector(e-vector,e{sup '}) process with high precision at Q{sup 2} values from 0.1 to 0.6 (GeV/c){sup 2}. The neutron magnetic form factor G{sub M}{sup n} was extracted at Q{sup 2} values of 0.1 and 0.2 (GeV/c){sup 2} using a nonrelativistic Faddeev calculation which includes both final-state interactions (FSI) and meson-exchange currents (MEC). Theoretical uncertainties due to the FSI and MEC effects were constrained with a precision measurement of the spin-dependent asymmetry in the threshold region of {sup 3}He-vector(e-vector,e{sup '}). We also extracted the neutron magnetic form factor G{sub M}{sup n} at Q{sup 2} values of 0.3 to 0.6 (GeV/c){sup 2} based on plane wave impulse approximation calculations.

The recoil proton polarization was measured in the {sup 2}H(e-vector,e{sup '}p-vector)n reaction in Hall A of the Thomas Jefferson National Accelerator Facility. The electron kinematics were centered on the quasielastic peak (x{sub Bj}{approx_equal}1) and included three values of the squared four-momentum transfer, Q{sup 2}=0.43,1.00 and 1.61 (GeV/c){sup 2}. For Q{sup 2}=0.43 and 1.61 (GeV/c){sup 2}, the missing momentum, p{sub m}, was centered at zero, whereas for Q{sup 2}=1.00 (GeV/c){sup 2} two values of p{sub m} were chosen: 0 and 174 MeV/c. At low p{sub m}, the Q{sup 2} dependence of the longitudinal polarization, P{sub z}{sup '}, is not well described by a state-of-the-art calculation. Further, at higher p{sub m}, a 3.5{sigma} discrepancy was observed in the transverse polarization, P{sub x}{sup '}. Understanding the origin of these discrepancies is important to confidently extract the neutron electric form factor from the analogous {sup 2}H(e-vector,e{sup '}n-vector)p experiment.

This paper was published online on 20 May 2005 without several of the authors' corrections incorporated. Equation (13) has been replaced. The captions of Figs. 16--18 have also been replaced. Typographical errors on pages 4, 6, 14, 15, 18, 19, 22, and 24 have all been corrected. The paper has been corrected as of 8 June 2005. The text is correct in the printed version of the journal.

We have studied the quasielastic He-3(e,e(')p)H-2 reaction in perpendicular coplanar kinematics, with the energy and the momentum transferred by the electron fixed at 840 MeV and 1502 MeV/c, respectively. The He-3(e,e(')p)H-2 cross section was measured for missing momenta up to 1000 MeV/c, while the A(TL) asymmetry was extracted for missing momenta up to 660 MeV/c. For missing momenta up to 150 MeV/c, the cross section is described by variational calculations using modern He-3 wave functions. For missing momenta from 150 to 750 MeV/c, strong final-state interaction effects are observed. Near 1000 MeV/c, the experimental cross section is more than an order of magnitude larger than predicted by available theories. The A(TL) asymmetry displays characteristic features of broken factorization with a structure that is similar to that generated by available models.

The physics program in Hall A at Jefferson Lab commenced in the summer of 1997 with a detailed investigation of the ^(16)O(e,e′p) reaction in quasielastic, constant (q,ω) kinematics at Q^2≈0.8(GeV/c)^2, q≈1GeV/c, and ω≈445MeV. Use of a self-calibrating, self-normalizing, thin-film waterfall target enabled a systematically rigorous measurement. Five-fold differential cross-section data for the removal of protons from the 1p-shell have been obtained for 0

We report a virtual Compton scattering study of the proton at low c.m. energies. We have determined the structure functions P(LL)-P(TT)/epsilon and P(LT), and the electric and magnetic generalized polarizabilities (GPs) alpha(E)(Q2) and beta(M)(Q2) at momentum transfer Q(2)=0.92 and 1.76 GeV2. The electric GP shows a strong falloff with Q2, and its global behavior does not follow a simple dipole form. The magnetic GP shows a rise and then a falloff; this can be interpreted as the dominance of a long-distance diamagnetic pion cloud at low Q2, compensated at higher Q2 by a paramagnetic contribution from piN intermediate states.

Exclusive electroproduction of pi{sup 0} mesons on protons in the backward hemisphere has been studied at Q2 = 1.0 GeV2 by detecting protons in the forward direction in coincidence with scattered electrons from the 4 GeV electron beam in Jefferson Lab's Hall A. The data span the range of the total (gamma*p) center-of-mass energy W from the pion production threshold to W = 2.0 GeV. The differential cross sections sigma{sub T} + epsilon sigma{sub L}, sigma{sub TL}, and sigma{sub TT} were separated from the azimuthal distribution and are presented together with the MAID and SAID parameterizations.

We have measured the nuclear transparency of the fundamental process $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{n}{\ensuremath{\pi}}^{\ensuremath{-}}p$ in ${}^{4}\mathrm{He}.$ These measurements were performed at Jefferson Lab in the photon energy range of 1.6--4.5 GeV and at ${\ensuremath{\theta}}_{\mathrm{cm}}^{\ensuremath{\pi}}=70\ifmmode^\circ\else\textdegree\fi{}$ and $90\ifmmode^\circ\else\textdegree\fi{}.$ These measurements are the first of their kind in the study of nuclear transparency in photoreactions. They also provide a benchmark test of Glauber calculations based on traditional models of nuclear physics. The transparency results suggest deviations from the traditional nuclear physics picture. The momentum transfer dependence of the measured nuclear transparency is consistent with Glauber calculations that include the quantum chromodynamics phenomenon of color transparency.

We have measured the proton recoil polarization in the 4He(e-->,e(')p-->)4H reaction at Q(2)=0.5, 1.0, 1.6, and 2.6 (GeV/c)(2). The measured ratio of polarization transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model. In addition, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control.

A high precision measurement of the transverse spin-dependent asymmetry A_T' in ^3He(e,e') quasielastic scattering was performed in Hall A at Jefferson Lab at values of the squared four-momentum transfer, Q^2, between 0.1 and 0.6 (GeV/c)^2. A_(T') is sensitive to the neutron magnetic form factor, G_M^n . Values of G_M^n at Q^2 = 0.1 and 0.2 (GeV/c)^2, extracted using Faddeev calculations, were reported previously. Here, we report the extraction of G_M^n for the remaining Q^2 values in the range from 0.3 to 0.6 (GeV/c)^2 using a plane-wave impulse approximation calculation. The results are in good agreement with recent precision data from experiments using a deuterium target.

We present data on the inclusive scattering of polarized electrons from a polarized ^3He target at energies from 0.862 to 5.06 GeV, obtained at a scattering angle of 15.5°. Our data include measurements from the quasielastic peak, through the nucleon resonance region, and beyond, and were used to determine the virtual photon cross-section difference σ_(1/2)-σ_(3/2). We extract the extended Gerasimov-Drell-Hearn integral for the neutron in the range of four-momentum transfer squared Q^2 of 0.1–0.9 GeV^2.

The coherent 3He(e,e{pi}+)3H reaction was measured at Q2 = 0.4 (GeV/c)2 and W = 1.6 GeV for two values of the virtual photon polarization, {epsilon}, allowing the separation of longitudinal and transverse cross sections. The results from the coherent process on 3He were compared to H(e,e{pi}+)n data taken at the same kinematics. This marks the first direct comparison of these processes. At these kinematics (p{pi} = 1.1 GeV/c), pion rescattering from the spectator nucleons in the 3He(e,e{pi}+)3H process is expected to be small, simplifying the comparison to {pi}+ production from the free proton.

Separated longitudinal and transverse cross sections for charged pion electroproduction from (1)H, (2)H, and (3)He were measured at Q(2) = 0.4 (GeV/c)(2) for two values of the invariant mass, W = 1.15 GeV and W = 1.60 GeV, in a search for a mass dependence which would signal the effect of nuclear pions. This is the first such study that includes recoil momenta significantly above the Fermi surface. The longitudinal cross section, if dominated by the pion-pole process, should be sensitive to nuclear pion currents. Comparisons of the longitudinal cross section target ratios to a quasifree calculation reveal a significant suppression in (3)He at W = 1.60 GeV. The W = 1.15 GeV results are consistent with simple estimates of the effect of nuclear pion currents, but are also consistent with pure quasifree production.

Double differential cross sections d{sup 2}{sigma}/d{omega}d{omega} and spin-flip probabilities S{sub nn} have been measured for the {sup 40}Ca(p(vector sign),p(vector sign){sup '}) reaction at E{sub p}=319 MeV. The angular range of the experiment was 10.5 degree sign {

Values of deformation parameters have been extracted from macroscopic coupled-channels analyses of inelastic proton scattering to the first 2 , 3 , and 4 states of SC over the energy range from 200 to 700 MeV. The apparent deformations are almost unchanged over this energy interval; they agree also with nucleon scattering data at much lower energies and at 800 MeV and 1 GeV.

Differential cross sections for the inelastic excitation of /sup 12/C by protons have been measured at 0.8 GeV; the range of the angular distribution corresponds to momentum transfers of 0.7--2.4 fm/sup -1/ (1--3.3 m/sub ..pi../). Data for the 1/sup +/(T = 0), 1/sup +/(T = 1), 2/sup +/(T = 1), and the 2/sup -/(T = 1) states at 12.71, 15.11, 16.11, and 16.58 MeV, respectively, have been obtained. These states, as well as the 2/sup +/(T = 0) state at 4.44 MeV, provide a sensitive test of different parts of the effective N-N interaction at 0.8 GeV. We conclude that the differential cross sections for the /sup 12/C excitations can be adequately described in the distorted-wave impulse approximation using a recently published t-matrix interaction.

The spin rotation parameter Q has been measured for p-/sup 40/Ca-elastic scattering at 497 MeV for 0.01< or =-t< or =0.15 (GeV/c)/sup 2/ with use of the new High Resolution Spectrometer focal plane polarimeter. In conjunction with analyzing power and differential cross section, this measurement uniquely determines the elastic scattering amplitudes up to an arbitrary phase. A parameter-free analysis within the Glauber diffractive approximation with use of N-N phase-shift solutions is presented.

The differential cross section for the reaction /sup 12/C(p,p')/sup 12/C* (15.11 MeV, 1/sup +/, T=1) has been measured at 800 MeV; the range of the angular distribution corresponds to momentum transfers of 0.7--2.4 fm/sup -1/ ((1-3.3)m/sub ..pi../). The cross section decreases almost exponentially at large angles; no maximum is observed in the region where nuclear critical opalescence might be expected.

Cross sections for the /sup 12/C(p,p') reaction leading to the 1/sup +/ states at 15.1 MeV(T = 1) and 12.7 MeV(T = 0) were measured at a bombarding energy of 402 MeV. These data, covering a range of momentum transfer q from 0.45 to 2.65 fm/sup -1/ (0.6 --3.7m/sub ..pi../) provide a test of the effects, precursor to a pion condensate, predicted to be important for the T = 1 state near q = 2--3m/sub ..pi../. The cross sections for the two 1/sup +/ states are very similar fro large q, perhaps indicating that the precursor effects are small.

New differential cross section and analyzing-power data for 800-MeV p/sub pol/ + /sup 12/C, /sup 116,124/Sn inelastic scattering to the first 2/sup +/ states are presented. A distorted-wave Born-approximation analysis which utilizes collective form factors and includes deformation of the spin-orbit potential is shown to provide a reasonable description of the analyzing-power data.

Differential cross sections have been measured for p+d\ensuremath{\rightarrow}\ensuremath{\gamma}${+}^{3}$He at ${T}_{\mathrm{p}}$(lab)=300, 350, 400, 425, 450, 470, and 500 MeV for ${\mathrm{theta}}_{\ensuremath{\gamma}}$(c.m.) near 60\ifmmode^\circ\else\textdegree\fi{} and 90\ifmmode^\circ\else\textdegree\fi{}. Measurements were also made for d+p\ensuremath{\rightarrow}\ensuremath{\gamma}${+}^{3}$He at ${T}_{\mathrm{d}}$=376 MeV for ${\mathrm{theta}}_{\ensuremath{\gamma}}$(c.m.)=84\ifmmode^\circ\else\textdegree\fi{}, 98\ifmmode^\circ\else\textdegree\fi{}, and 113\ifmmode^\circ\else\textdegree\fi{}, and at ${T}_{\mathrm{d}}$=600 MeV for ${\mathrm{theta}}_{\ensuremath{\gamma}}$=96\ifmmode^\circ\else\textdegree\fi{} and 105\ifmmode^\circ\else\textdegree\fi{}. Our results are in agreement with those of the inverse reaction, \ensuremath{\gamma}${+}^{3}$He\ensuremath{\rightarrow}p+d of Sober et al., as is expected from time-reversal invariance. Our data agree with the latest results of Cameron et al. The older radiative capture measurements of Heusch et al. and the photodisintegration measurements made at other laboratories differ significantly from our results. Our data are compared with three theoretical models; the one proposed by Maximon and Prats comes closest to describing the data.

The explicit expressions of Amado et al. for elastic scattering observables for protons at intermediate energies have been applied to data at 500 and 800 MeV. Analyses were performed using both the analytic form of the solutions and data-to-data relations. Good fits are obtained with few parameters; however, these seem to have only phenomenological significance.

The observation of $\ensuremath{\Lambda}$-hypernuclear levels in $_{\ensuremath{\Lambda}}^{12}\mathrm{C}$ by associated production through the (${\ensuremath{\pi}}^{+}, {K}^{+}$) reaction is reported. The $_{\ensuremath{\Lambda}}^{12}\mathrm{C}$ excitation-energy spectra were recorded at laboratory scattering angles of 5.6\ifmmode^\circ\else\textdegree\fi{}, 10.3\ifmmode^\circ\else\textdegree\fi{}, and 15.2\ifmmode^\circ\else\textdegree\fi{}. They show two major peaks---one attributed to the ground state, and one about 11 MeV higher. These results are compared to the strangeness-exchanging (${K}^{\ensuremath{-}}, {\ensuremath{\pi}}^{\ensuremath{-}}$) reaction. The measured cross sections are compared to relativistic distorted-wave Born-approximation calculations.

Cross sections, analyzing powers, and spin-flip probabilities have been measured at small angles in the reaction $^{90}\mathrm{Zr}(p,{p}^{\ensuremath{'}})^{90}\mathrm{Zr}^{*}$ at 319 MeV. A rich fine structure is observed in the previously proposed $M1$ giant resonance region; angular distributions of most of these structures are consistent with $M1$ excitation. The spin-flip measurements reveal a large cross section for spin excitations distributed roughly uniformly over the excitation energy region from about 8 to 25 MeV.

Recently derived data-to-data (DTD) relations have been applied to elastic and inelastic scattering of 800-MeV protons from /sup 90/Zr and /sup 92/Zr. Significant differences between the cross sections for the 2/sub 1//sup ts+/ and 4/sub 1//sup ts+/ states in the two nuclei suggest that DTD relations between elastic and inelastic cross sections are inadequate. Nevertheless, the DTD relation which predicts the analyzing power (A/sub y/) from the cross section for inelastic transitions yields excellent agreement with the data. The physical significance of the fitting parameters is discussed.

Measurements of spin-flip probabilities for inelastic scattering of 318 MeV protons from /sup 40/Ca reveal that much of the background underlying the giant dipole and quadrupole resonances at small angles is from ..delta..S = 1 transitions. This holds the promise of allowing a much better estimate of this background than has previously been possible;one model-dependent parameter is necessary. Subsequent analysis with a first estimate of this parameter is presented

Spin-flip probabilities have been measured for inelastic proton scattering from /sup 40/Ca at 319 MeV at angles between 3/sup 0/ and 12/sup 0/ and excitation energies up to about 40 MeV. These data can be directly related to the relative ((spin transfer)/(no spin transfer)) nuclear response via one model-dependent variable. Nuclear spin excitations appear relatively suppressed at low excitation energies but surprisingly enhanced at the highest excitation energies at intermediate angles. Many features of the data can be explained with a slab nuclear response with random-phase-approximation correlations.

Angular distributions of the double differential cross section {ital d}{sup 2}{sigma}/d{Omega} dE({sigma}) and the spin-flip probability {ital S}{sub {ital nn}} have been measured for inclusive proton inelastic scattering from {sup 40}Ca at 319 MeV. Excitation energies ({omega}) up to about 40 MeV have been investigated over the angular range from 3.5{degree} to 12{degree} in the laboratory (0.3 to 0.9 fm{sup {minus}1}). Here, multipole decompositions of angular distributions of {sigma}{ital S}{sub {ital nn}} for the {sup 40}Ca({ital {rvec p}},{ital {rvec p}} {prime}) reaction at 319 MeV have been performed in order to compare {Delta}{ital S}=1 strength observed with sum rules. In contrast to the well-known quenching of Gamow-Teller and {ital M}1 resonances, the spin-dipole resonance has a total measured strength which is larger than that predicted by the energy-weighted sum rule. The spin-dipole strength distribution supports asymmetric widths predicted by calculations including 2p-2h mixing. The spin-quadrupole resonance is observed near {omega}=35 MeV and its total strength for {omega}{lt}40 MeV estimated.

Author(s): Glashausser, C.; Swiniarski, R. de; Goudergues, J.; Lombard, R.M.; Mayer, B.; Thirion, J.

The sign and magnitude of the haxadecapole deformation in $^{20}\mathrm{Ne}$ is determined from measurements of the inelastic scattering of 24.5-MeV protons. A coupled-channels analysis yields a value for ${\ensuremath{\beta}}_{4}$ of + 0.28. A similar analysis of other available data in the $s\ensuremath{-}d$ shell suggests a large hexadecapole deformation in $^{28}\mathrm{Si}$ (+0.25) and $^{32}\mathrm{S}$ (+0.25); $^{24}\mathrm{Mg}$ is found to have a ${Y}_{4}$ moment close to zero.