Search

Double differential cross sections and analyzing powers over the quasielastic region have been measured using the ({ital {rvec p}},{ital n}) reaction on {sup 12}C and {sup nat}Pb. The data were obtained at proton energies of 495 and 795 MeV and cover momentum transfers from 1.0--2.1 fm{sup {minus}1} at 495 MeV data and from 0.0--3.5 fm{sup {minus}1} at 795 MeV. The cross section data are compared to results from a nonrelativistic reaction model that includes contributions from two-step scattering. The analyzing power measurements are compared to a recent relativistic plane-waves model.

Complete sets of polarization transfer coefficients have been measured for quasifree ([ital [rvec p]],[ital [rvec n]]) scattering from [sup 2]H, [sup 12]C, and [sup 40]Ca at 494 MeV and scattering angles of 12.5[degree], 18[degree], and 27[degree] ([ital q]=1.2,1.7,2.5 fm[sup [minus]1]). These measurements yield separated transverse ([sigma] [times]/I[ital q]) and longitudinal ([sigma] [center dot]/I[ital q]) isovector spin responses. Comparison of the separated responses to calculations and to electron-scattering responses reveals a strong enhancement in the spin transverse channel. This excess transverse strength masks the effect of pionic correlations in the response ratio.

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.

The polarization transfer observable [ital D][sub [ital L][ital L]](0[degree]) has been measured for [sup 2]H([ital [rvec p]],[ital [rvec n]])2[ital p], [sup 12]C([ital [rvec p]],[ital [rvec n]])[sup 12]N, and [sup 14]C([ital [rvec p]],[ital [rvec n]])[sup 14]N reactions with beam energies of 318 and 494 MeV. The deuterium results are in close agreement with free [ital NN] scattering constrained to the [Delta][ital J][sup [pi]]=1[sup +] channel. The results for the carbon targets, however, are systematically more negative than those for deuterium, which suggests a difference between the free and effective nucleon-nucleon interactions. Such a medium modification of the spin-dependent interaction may have important implications for intepretation of other intermediate-energy scattering experiments.

A complete set of polarization-transfer observables has been measured for quasifree (p\ensuremath{\rightarrow},n\ensuremath{\rightarrow}) reactions on $^{2}\mathrm{H}$, $^{12}\mathrm{C}$, and $^{40}\mathrm{Ca}$ at a bombarding energy of 495 MeV and a laboratory scattering angle of 18\ifmmode^\circ\else\textdegree\fi{}. The data span an energy-loss range from 0 to 160 MeV, with a corresponding momentum transfer range of ${\mathit{q}}_{\mathrm{c}.\mathrm{m}.}$=1.7--1.9 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$. The laboratory observables are used to construct partial cross sections proportional to the nonspin response and three orthogonal spin responses. These results are compared to the transverse spin response measured in deep inelastic electron scattering and to nuclear responses based on the random phase approximation. The polarization observables for all three targets are remarkably similar and reveal no evidence for an enhancement of the spin-longitudinal nuclear response relative to the spin-transverse response. These results suggest the need for substantial modifications to the standard form assumed for the residual particle-hole interaction.

A complete set of polarization transfer observables for quasifree scattering in the ({rvec p}, {rvec n}) reaction at 495 MeV is reported. Measurements were carried out on CD{sub 2}, natural carbon, and calcium targets at a momentum transfer of 1.72 fm{sup {minus}1} using the new Neutron Time-of-Flight facility at LAMPF. The spin-longitudinal and spin-transverse responses are extracted from the data. The ratio of these responses are compared to DWIA-RPA calculations in which the particle-hole interaction is taken to be of the form g{prime}+{pi}+{rho}. No evidence for these RPA correlations is seen in the data at this momentum transfer. 8 refs., 2 figs.

Complete spin-transfer observables for the two lowest ${1}^{+}$ levels in $^{12}\mathrm{C}$ have been studied with incident protons of 500 MeV. Outgoing protons were detected with an energy resolution of 120 keV at laboratory angles of 3.5\ifmmode^\circ\else\textdegree\fi{}, 5.0\ifmmode^\circ\else\textdegree\fi{}, 7.5\ifmmode^\circ\else\textdegree\fi{}, 9.5\ifmmode^\circ\else\textdegree\fi{}, and 12.5\ifmmode^\circ\else\textdegree\fi{}. Angular distributions of differential cross sections, analyzing powers, and the individual spin observables for each ${1}^{+}$ state are recombined into three transverse and one longitudinal partial differential cross section as well as the spin-sum and spin-difference functions. Results are compared with model calculations and electron-scattering data. Information about experimental quantities not accessible in electron scattering is also discussed.

Differential cross sections and analyzing powers have been measured for the excitation by 318 MeV protons of states of $^{40}\mathrm{Ca}$ below 7.2 MeV. The data for those normal-parity excitations for which transition densities are available from electroexcitation measurements are analyzed in terms of medium modifications to the nucleon-nucleon interaction. We find that the empirical effective interaction previously fitted to $^{16}\mathrm{O}$(p,p') data at the same energy predicts $^{40}\mathrm{Ca}$(p,p') very well. Density-dependent modifications of the effective interaction fitted to data for $^{40}\mathrm{Ca}$ or $^{16}\mathrm{O}$, either independently or simultaneously, are virtually identical. The density dependence of the empirical interaction is considerably stronger than that of interactions based upon nonrelativistic nuclear matter theory and persists to lower density. The most significant differences are that the empirical interaction has a stronger repulsive core and that absorption is enhanced at high density, contrary to expectations based upon Pauli blocking. We also find substantial suppression of the spin-orbit interaction at low density and enhancement at high density. Nevertheless, the independence of the effective interaction from the target supports the concept of local nuclear matter density. We also find that optical potentials based upon the empirical effective interaction are very similar to Schr\"odinger-equivalent potentials based upon a relativistic impulse approximation model, suggesting that the empirical density dependence is similar to the equivalent density dependence that arises from elimination of lower components from Dirac wave functions. Finally, the results are compared with global optical potentials from Dirac phenomenology.

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

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.

Zero-degree cross sections have been measured for the {sup 11}B({ital p},{ital n}){sup 11}C reaction at bombarding energies of {ital E}{sub {ital p}}=160, 200, 494, 644, and 795 MeV. In addition, spectra have been obtained at laboratory scattering angles of 3{degree} and 5{degree} at 494 MeV, and the transverse spin-flip probability at zero degrees has been measured for {ital E}{sub {ital p}}=160 MeV. These data are used to obtain estimates of the Gamow-Teller transition strength to final states in {sup 11}C up to an excitation energy of {ital E}{sub {ital x}}{approx equal}14 MeV. The uncertainty (1 standard deviation) in the extracted transition strengths is estimated to be in the range (2--8)%. Measured cross sections for the first four excited states in {sup 11}C have been compared to distorted-wave impulse approximation calculations. In this comparison, no evidence is found in the cross-section data for certain effects associated with knock-on exchange and noncentral interactions.

Cross sections at 0{degree} for the pure Fermi (0{sup +}, 2.31, MeV) and Gamow-Teller (1{sup +}, 3.95 MeV) states in the {sup 14}C({ital p},{ital n}){sup 14}N reaction have been measured at {ital E}{sub {ital p}}=494, 644, and 795 MeV using the LAMPF neutron time-of-flight facility with a new 617-m neutron flight path. The measured cross sections per unit transition strength, {cflx {sigma}}, provide a measure of the isovector spin-flip and non-spin-flip central components of the effective nucleon-nucleon interaction. Cross sections and the ratio {ital R}{sup 2}={cflx {sigma}}{sub GT}/{cflx {sigma}}{sub F} are compared to lower-energy measurements and to calculations using a free {ital NN} {ital t} matrix.

Differential-cross-section distributions for the {sup 7}Li({ital p},{ital n}){sup 7}Be(g.s.+0.43-MeV) reaction have been measured for {ital E}{sub {ital p}}=80, 120, 160, 200, 494, 644, and 795 MeV. These distributions have been integrated and normalized to independent values for the total cross section obtained from parametrizations of {sup 7}Li({ital p},{ital n}) activation measurements. Zero-degree cross sections obtained from this normalization are reported.

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.

Using a liquid deuterium target, 800 MeV quasielastic $\stackrel{\ensuremath{\rightarrow}}{p}+n$ and $\stackrel{\ensuremath{\rightarrow}}{p}+p$ analyzing powers were measured over the center-of-momentum angular range 14\ifmmode^\circ\else\textdegree\fi{}-75\ifmmode^\circ\else\textdegree\fi{}. Elastic $\stackrel{\ensuremath{\rightarrow}}{p}+p$ analyzing powers were measured over the center-of-momentum angular range 10\ifmmode^\circ\else\textdegree\fi{}-47\ifmmode^\circ\else\textdegree\fi{} using a liquid hydrogen target, and elastic $p+p$ differential cross sections were obtained over the angular range 6\ifmmode^\circ\else\textdegree\fi{}-90\ifmmode^\circ\else\textdegree\fi{} using CH and C${\mathrm{H}}_{2}$ targets. The quasielastic $\stackrel{\ensuremath{\rightarrow}}{p}+p$ data are in good agreement with existing elastic $\stackrel{\ensuremath{\rightarrow}}{p}+p$ data, suggesting that the effects of final state interactions and Fermi motion averaging are small at this energy for the range of momentum transfer covered by these data. Results of phase shift analyses are reported, and the amplitudes important to microscopic analysis of 800 MeV $\stackrel{\ensuremath{\rightarrow}}{p}$+nucleus elastic differential cross section and analyzing power data are discussed. Use of these amplitudes to generate the microscopic Kerman-McManus-Thaler optical potential for 800 MeV $\stackrel{\ensuremath{\rightarrow}}{p}$+$^{40}\mathrm{Ca}$ elastic scattering does not resolve the problems encountered previously concerning nuclear size information and poor fits to the analyzing power data.NUCLEAR REACTIONS $^{2}\mathrm{H}(\stackrel{\ensuremath{\rightarrow}}{p}, pn)p$, $^{2}\mathrm{H}(\stackrel{\ensuremath{\rightarrow}}{p}, pp)n$, $^{1}\mathrm{H}(\stackrel{\ensuremath{\rightarrow}}{p}, p)$, $^{1}\mathrm{H}(p, p)$; ${E}_{p,\mathrm{inc}}=800$ MeV; measured $p+p$ elastic $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}$ for $6\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}{\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}\ensuremath{\le}90\ifmmode^\circ\else\textdegree\fi{}$; measured $\stackrel{\ensuremath{\rightarrow}}{p}+p$ elastic ${A}_{y}(\ensuremath{\theta})$ for $10\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}{\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}}\ensuremath{\le}47\ifmmode^\circ\else\textdegree\fi{}$; measured $\stackrel{\ensuremath{\rightarrow}}{p}+p$ and $\stackrel{\ensuremath{\rightarrow}}{p}+n$ quasielastic ${A}_{y}(\ensuremath{\theta})$ for $14\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}{\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}\ensuremath{\le}75\ifmmode^\circ\else\textdegree\fi{}$; CH, C${\mathrm{H}}_{2}$, liquid hydrogen and liquid deuterium targets; two arm coincidence for quasielastic; phase shift analyses; microscopic (KMT) optical model calculations for 800 MeV $\stackrel{\ensuremath{\rightarrow}}{p}$+$^{40}\mathrm{Ca}$.

A set of proton spin observables has been measured for the inelastic transitions to the ${3}^{\ensuremath{-}}$ (3.73 MeV) and ${5}^{\ensuremath{-}}$ (4.48 MeV) states in the $^{40}\mathrm{Ca}(p, {p}^{\ensuremath{'}})^{40}\mathrm{Ca}$ reaction and for the ${3}^{\ensuremath{-}}$ (2.61 MeV) state in the $^{208}\mathrm{Pb}(p, {p}^{\ensuremath{'}})^{208}\mathrm{Pb}$ reaction at 497 MeV. The interval of laboratory scattering angles was 6 to 20\ifmmode^\circ\else\textdegree\fi{} for $^{40}\mathrm{Ca}$ and 2.5 to 14\ifmmode^\circ\else\textdegree\fi{} for $^{208}\mathrm{Pb}$. Comparison of these observables reveals that they satisfy relations analogous to those valid in the elastic scattering of spin \textonehalf{} and spin 0 objects. The origin of these observed relations is explained.NUCLEAR REACTIONS Relations between spin observables in $^{40}\mathrm{Ca}(p, {p}^{\ensuremath{'}})^{40}\mathrm{Ca}$ and $^{208}\mathrm{Pb}(p, {p}^{\ensuremath{'}})^{208}\mathrm{Pb}$ at 500 MeV.

Proton cross sections for $^{208}\mathrm{Pb}$ have been measured for elastic and inelastic scattering to the ${12}^{+}$, 6.10 MeV, ${12}_{1}^{\mathrm{\ensuremath{-}}}$, 6.43 MeV, ${12}_{2}^{\mathrm{\ensuremath{-}}}$, 7.06 MeV, and ${14}^{\mathrm{\ensuremath{-}}}$, 6.74 MeV states at ${E}_{\mathrm{p}=318}$ MeV. We analyze the inelastic transitions in the distorted wave impulse approximation and use the previously published electron scattering results to constrain the wave functions in the unnatural parity calculations. A ${13}^{\mathrm{\ensuremath{-}}}$ state is discussed as an unresolved ``contaminant'' to the ${12}_{1}^{\mathrm{\ensuremath{-}}}$, 6.43 MeV state. Mixing between the ${12}^{\mathrm{\ensuremath{-}}}$ neutron and proton particle-hole configurations is found to reduce substantially the differences reported previously in observed proton and electron quenching factors. This results in greater quenching for the ${12}_{2}^{\mathrm{\ensuremath{-}}}$, 7.06 MeV state, and less quenching for the ${12}_{1}^{\mathrm{\ensuremath{-}}}$, 6.43 MeV state than was previously reported in (e,e') analyses.

Differential cross sections sigma(theta) and analyzing powers A(theta) for pp elastic scattering have been measured in the Coulomb-nuclear interference region at 800 MeV. The measurements, which extend down to 0.5 deg in the laboratory, have been analyzed to deduce the zero-degree pp scattering amplitudes. The ratio rho of the real to imaginary parts of the spin-independent amplitude was found to be -0.04 +- 0.04; the contribution of the double-spin-flip amplitudes to sigma(0) was found to be 0.16 +- 0.03 times that of the spin-independent amplitude; while the ratios of the imaginary and real parts of the single spin-flip amplitude to sintheta were found to be 0.74 +- 0.04 and -0.03 +- 0.08 fm, respectively. Except for the last, these experimental values agree with the predictions of forward dispersion relations and phase shift analyses.

We have used a polarized proton beam to measure the analyzing power for pd backward elastic scattering at incident kinetic energies of 0.68, 1.03, and 1.53 GeV and for the reaction p + p ..-->.. d + ..pi.. at 1.03 GeV. The data indicate that several mechanisms dominate pd backward elastic scattering over this energy range.

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 elastic scattering of 800 MeV polarized protons, with longitudinal, normal, and sideways orientations, from deuterons polarized normal to the scattering plane has been measured. The four-momentum transfer interval measured in this experiment is from 0.03 to 0.17 (GeV/c)/sup 2/. Spin-correlation and spin-transfer observables have been extracted from the data. This experiment is one of a series designed to determine a number of observables in excess of the minimum number required to reconstruct the 12 subamplitudes of the proton-deuteron elastic scattering amplitude directly from spin observables. A comparison of the data with theoretical calculations employing three different phase-shift solutions for NN amplitudes reveals that sizable ambiguities exist in the values of NN amplitudes at small momentum transfers.

It has been suggested that bags containing more than three interacting quarks may be formed in high-energy collisions; these states would appear as narrow resonances in the inelastic channels. We have measured the inclusive cross section d+/sup 4/He..-->..p+X at E/sub c.m./=6.25 to 7.91 GeV in steps of 50 to 100 MeV to search for an eighteen-quark bag resonance. No evidence for narrow resonances was found and upper limits on the production cross section are presented.

Inelastic scattering of 800-MeV protons from $^{40}\mathrm{Ca}$, $^{116}\mathrm{Sn}$, and $^{208}\mathrm{Pb}$ shows a broad giant resonance at an excitation energy of $\frac{110}{{A}^{\frac{1}{3}}}$ MeV. The angular distributions are consistent only with scalar-isoscalar $l=3$ transfer. The excitation energy and width of this high-energy octupole giant resonance are in reasonable accord with theory. However, its energy-weighted sum-rule strength (\ensuremath{\sim}20%) is only about one half that predicted by randomphase-approximation calculations.

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.

The energy spectra of deuterons recoiling from a deuterium gas target bombarded by transversely polarized 796-MeV protons have been measured to obtain the differential cross sections, dsigma/dt, and analyzing powers, A/sub y/(t), for p-d elastic scattering over a range of laboratory angles from 4.53/sup 0/ to 13.02/sup 0/, corresponding to a range of four-momentum transfer squared, Vertical BartVertical Bar, from 0.013 to 0.108 GeV/sup 2//c/sup 2/. Employing several sets of nucleon-nucleon, N-N, amplitudes obtained from N-N phase shift analyses, comparisons are made between the experimental data and the predictions of a multiple scattering theory. In this region of four-momentum transfer, A/sub y/ is shown to depend almost entirely on the spin-independent and spin-orbit N-N amplitudes.

The elastic differential cross sections of 7.0-GeV/c /sup 4/He scattered from hydrogen (equivalent T/sub p/ = 1.05 GeV) has been measured over a range 0.17 < or = - t < or = 0.85(GeV/c)/sup 2/. The experiment has very low background (< or = 2%), adequate t resolution (< or = 5%), a good absolute normalization (15%), and a statistical accuracy in the interference region of about 3%. The data show a shallow first minimum and a shape very similar to the recent data from Centres d'Etudes Nucleaires de Saclay.

Differential cross section measurements have been made for the giantresonance region (13.2--40 MeV) in /sup 40/Ca using 500 MeVprotons with an experimental energy resolution of 70 keV. Fine structure wasobserved in this energy region. After fixing the energy weighted sum ruledepletion for the isovector giant dipole resonance at 70%, energy weighted sumrules of 70+-14 % for the isoscalar giant quadrupole resonanceand 15+-3 % for the isoscalar giant hexadecapole resonance werededuced. All of these energy weighted sum rule depletions agree well withtheoretical predictions and results from other experiments.

Differential cross sections are reported for ..pi../sup +/+/sup 3,4/He elastic scattering at 260, 295, and 310 MeV and ..pi../sup -/+/sup 3,4/He at 295 MeV. The angular distributions )except for ..pi../sup -/+/sup 3/He) confirm the fixed angle (thetaapprox. =75/sup 0/) minimum seen at lower energies (caused by the (3,3) ..pi..+N resonance dominance) and show a deep minimum at thetaapprox. =110/sup 0/. Comparisons are made to ..pi..+d and the current discussion of pion excitation of intermediate dibaryon and ..delta..N states.

Measurements for spin observables for elastic scattering of 320, 400, 500, 650, and 800 MeV protons from /sup 16/O and /sup 40/Ca are reported. Comparisons of the data with theoretical calculations were carried out in the framework of nonrelativistic and relativistic approaches. The differences between the relativistic and nonrelativistic predictions are found, in agreement with earlier theoretical predictions, to decrease with the increasing energy. The trend can be best seen by examining the data for the spin-down channel differential cross sections. Unlike the spin-up cross sections, they are sensitive to the relativistic corrections. For all targets and energies considered, predictions of the relativistic and nonrelativistic approaches are similar and agree with the spin-up channel data. The predictions differ considerably in the spin-down channel.

Measurements of the tensor and vector spin observables C(0,NN,0,0), C(0,SS,0,0), and C(0,N,0,0), in p-d elastic scattering at 600, 800, and 1000 MeV equivalent proton bombarding energy, are reported. The data were taken in the range 0.1

Zero-degree (p,n) cross sections, measured with approximately 1-MeV energy resolution at ${E}_{p}$=492 MeV, are reported for $^{7}\mathrm{Li}$, $^{11}\mathrm{B}$, and $^{12}$,13,14C. Measurements for $^{11}\mathrm{B}$(p,n) and $^{13}\mathrm{C}$(p,n) were also obtained at 590 MeV. The cross sections for Gamow-Teller and Fermi type transitions are used to estimate the strengths of the isovector spin-dependent (${J}_{\ensuremath{\sigma}\ensuremath{\tau}}$) and spin-independent (${J}_{\ensuremath{\tau}}$) terms of the effective interaction. The measured zero-degree cross sections for the $^{14}\mathrm{C}$(p,n${)}^{14}$N transitions to the 2.31 MeV isobaric analog state and the 3.95-MeV ${J}^{\ensuremath{\pi}}$${=1}^{+}$ state are compared with calculated values. Values for the unit cross-section ratio ${R}^{2}$=\ensuremath{\sigma}${^}_{\mathrm{GT}}$/\ensuremath{\sigma}${^}_{F}$ =(${J}_{\ensuremath{\sigma}\ensuremath{\tau}}$/${J}_{\ensuremath{\tau}}$${)}^{2}$ (${N}_{\ensuremath{\sigma}\ensuremath{\tau}}$/${N}_{\ensuremath{\tau}}$) obtained from the present data are compared with results for other energies.

Large angle elastic differential cross section and analyzing power data are reported for 497.5 MeV p-arrow-right+/sup 40/Ca. The characteristic diffraction pattern extends to the largest momentum transfer, 5.3 fm/sup -1/. Theoretical models which incorporate either relativistic or nonrelativistic dynamics do not quantitatively describe the data for q>3.5 fm/sup -1/. Possible explanations for the discrepancy are suggested

800 MeV elastic p+p spin-depolarization and -rotation parameters D/sub N/N, D/sub S/S, D/sub L/L, D/sub S/L, and D/sub L/S have been measured for the center-of-momentum angular range 4.8/sup 0/--23.8/sup 0/ (0.26 fm/sup -1/< or =q< or =1.28 fm/sup -1/). Statistical uncertainties are approx. = +- 0.01--0.02 and total systematic uncertainty is < or = +- 0.035. The data are in overall agreement with predictions from global phase shift analysis.

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.

The structure of giant resonances in /sup 208/Pb has been studied using inelastic scattering of 334-MeV polarized protons. Data were obtained with 70-keV energy resolution over an angular range from 2--13 deg and the spectra were measured over an excitation energy range from 0--25 MeV. The results show that the quadrupole resonance strength is divided into two main components, one centered at 10.6 MeV containing 70% of the energy-weighted sum rule in a 2-MeV wide peak and a second component composed of several discrete peaks located between 7 and 9 MeV which deplete a total of approximately 20% of the energy-weighted sum rule. The giant monopole and dipole resonances as well as a hexadecapole resonance are observed. Measurements of differential cross sections for elastic scattering and inelastic scattering to low-lying 3/sup -/, 2/sup +/, and 4/sup +/ levels are presented. Comparison of these data with collective model direct reaction calculations shows the calculations to correctly describe the shape and magnitude of the cross sections when normalized to the known transition rates for each level.

The inelastic cross sections and analyzing powers for spin excitations in /sup 40,48/Ca have been measured at E/sub p/ = 334 MeV. The data for excited states in /sup 40/Ca at 8.424 MeV (2/sup -/) and 10.31 MeV (1/sup +/) and the 10.22-MeV (1/sup +/) state in /sup 48/Ca are fairly well described by microscopic distorted-wave impulse approximation calculations. Normalizations of the calculated cross sections to the experimental data show that these spin excitations are quenched. We deduce B(M2)up-arrow = 281 ..mu../sub N//sup 2/fm/sup 2/ for the 8.42-MeV 2/sup -/ state in /sup 40/Ca.

Inelastic scattering of 800 MeV protons has been studied for targets of /sup 208/Pb, /sup 144/Sm, and /sup 116/Sn. At excitation energies above particle emission threshold a spectrum of giant resonances is clearly in evidence. Angular distributions were extracted for the high-lying peaks (approx.20 MeV excitation energy) in /sup 208/Pb and /sup 144/Sm. Collective model distorted-wave Born approximation analyses of these data show that isoscalar octupole and dipole states dominate the spectra.

Measurements are reported for the elastic and inelastic scattering of 800 MeV protons from $^{40}\mathrm{Ca}$. Differential cross sections were measured out to 42\ifmmode^\circ\else\textdegree\fi{} while analyzing powers were obtained out to 30\ifmmode^\circ\else\textdegree\fi{}. The angular distributions are diffractive in character at all angles. Theoretical analysis of the data was carried out in the framework of the diffraction multiple scattering theory. The following results were obtained: (i) Diffraction multiple scattering theory reproduces the data qualitatively out to the large momentum transfers. (ii) For the ground state density distribution ${〈{{r}_{p}}^{2}〉}^{\frac{1}{2}}\ensuremath{-}{〈{{r}_{n}}^{2}〉}^{\frac{1}{2}}=0.142\ifmmode\pm\else\textpm\fi{}0.075$ fm is obtained and the analysis favors the value of the correlation length ${\ensuremath{\xi}}_{c}=\ensuremath{-}0.5$ fm. (iii) The excitation of the lowest-lying collective states (${3}^{\ensuremath{-}}$, ${5}^{\ensuremath{-}}$, ${2}^{+}$) was analyzed using one-phonon excitation macroscopic parameters. The values of the ${\ensuremath{\beta}}_{2}$, ${\ensuremath{\beta}}_{3}$, ${\ensuremath{\beta}}_{5}$ parameters obtained agree quantitatively with lower energy ($p$,${p}^{\ensuremath{'}}$) scattering results.

Measurements of the spin-flip probability for states in /sup 12/C excited by 397 MeV protons are presented. These data are compared with distorted-wave Born approximation and plane-wave calculations using Cohen-Kurath wave functions as well as simpler transition densities. The results are discussed in terms of the implications for nuclear structure as well as the nucleon-nucleon effective interaction.

The spin-rotation parameter Q(theta) was measured for 800 MeV p\ensuremath{\rightarrow}${+}^{16}$O, $^{40}\mathrm{Ca}$, and $^{208}\mathrm{Pb}$ elastic scattering for 2\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}${\mathrm{theta}}_{\mathrm{lab}\mathrm{\ensuremath{\le}}21\mathrm{\ifmmode^\circ\else\textdegree\fi{}}}$. Microscopic ``relativistic'' (Dirac equation dynamics) and ``nonrelativistic'' (Schr\"odinger equation dynamics) optical model predictions are compared with the data. Slight preference for the relativistic impulse approximation approach is observed, but a marked mass dependence of the quality of the fit is evident. Other calculations are presented which suggest that inclusion of nuclear two-body correlation effects in the relativistic impulse approximation model might lead to better agreement with experiment.

Proton spectra of /sup 3,4/He(..pi../sup + -/,p) and /sup 27/Al(..pi../sup + -/,p) have been measured at theta/sub p/ = 20/sup 0/ for T/sub ..pi../ = 50, 100, 150, 200, and 250 MeV, and at theta/sub p/ = 20/sup 0/ and 40/sup 0/ for T/sub ..pi../ = 295 MeV. A small contributor to these spectra is the exclusive pion absorption reaction for which the cross section of /sup 4/He(..pi../sup +/,p)/sup 3/He is reported. Major contributions are identified to come from quasifree ..pi..N..--> pi..p scattering and ..pi..NN..-->..Np absorption for which cross sections are also reported. The quasifree cross sections are compared with those of the free reactions ..pi..N..--> pi..p and ..pi..d..-->..pp. We use these results to assess the contribution of quasifree reactions to the total reaction cross section. The comparison of the quasifree ..pi..NN..-->..Np reaction relative to ..pi..d..-->..pp is discussed in terms of differences in the attenuation and the dynamics of the reactions. This information is of interest for the phenomenological interpretation of complex reactions such as the two-nucleon absorption model of /sup 3/He(..pi../sup -/, n)/sup 2/H, /sup 4/He(..pi../sup -/, n)/sup 3/H, and /sup 4/He(..pi../sup +/, p)/sup 3/He in which ..pi..d..-->..pp is assumed to be an elementary process. This experiment also providesmore » information on the cross section of ..pi../sup -/pp..-->..pn from which we determine the dependence of pion absorption on the isospin of the initial NN state.« less

A vibrational collective model has been used to analyze 15 bound states in /sup 40/Ca excited by inelastic scattering of 500 MeV polarized protons. It is shown that for those states which have surface peaked charge transition densities the collective model describes the shape and magnitude of the angular distributions quite well. The hadronic deformation lengths extracted are shown to be constant over the incident proton energy range of 25--800 MeV with the exception of data at 185 MeV. The average values for the hadronic deformation lengths are used to calculate the ratio of the neutron to proton multipole matrix elements for five states. Elastic scattering and the 3/sub 1//sup -/, 2/sub 1//sup +/, and 5/sub 1//sup -/ transitions have also been studied using the relativistic collective model.

The cross section and transverse polarization transfer for the $^{2}\mathrm{H}$(p,n)2p reaction at ${E}_{\mathrm{p}=160}$ MeV and theta=0\ifmmode^\circ\else\textdegree\fi{} have been measured with good energy resolution (1 MeV). An asymmetric peak shape characteristic of the $^{1}\mathrm{S}_{0}$ final-state interaction of the residual two-proton system has been clearly observed. The measured transverse polarization transfer coefficient for this peak is ${D}_{\mathrm{NN}}$(0?(de)=-0.43\ifmmode\pm\else\textpm\fi{}0.04. A simple impulse approximation calculation including the $^{1}\mathrm{S}_{0}$ final-state interaction reproduces the main features of the observed peak shape and polarization transfer. Small discrepancies observed in the peak tail region can be accounted for by including the $^{3}\mathrm{P}_{0}$,1,2 final state interaction.

We have measured the differential cross section d/sup 2/sigma/d..cap omega.. dT and estimated the total cross section sigma/sub T/ for the double charge exchange reaction /sup 4/He(..pi../sup +/,..pi../sup -/)4p at 140, 200, and 295 MeV. The values for sigma/sub T/ are at least an order of magnitude larger than predictions based on sequential single charge exchange ..pi..-N scatterings. It is possible, therefore, that /sup 4/He(..pi../sup +/,..pi../sup -/) is dominated by other processes, such as the formation of a ..delta.. in the intermediate state or scattering from meson exchange currents.

By measuring the energy spectra of recoil particles, the following data have been obtained at an incident proton energy of 796 MeV: (1) the differential cross section for proton-proton (p-p) elastic scattering at laboratory angles between 1.37/sup 0/ and 6.40/sup 0/, and (2) the analyzing power for p-p elastic scattering at laboratory angles between 3.13/sup 0/ and 6.40/sup 0/. Analyses of these data have determined certain parameters characterizing the nuclear amplitude for p-p elastic scattering. The ratio, rho, of the real to the imaginary parts of the forward p-p spin independent amplitude was found to be +0.005 +- 0.04. The ratio R of the summed moduli squared of the forward p-p double spin flip scattering amplitudes to the modulus squared of the forward p-p spin independent amplitude was found to be 0.16 +- 0.03. The real and imaginary parts of the p-p spin orbit scattering amplitude divided by sintheta were found to be 0.72 +- 0.05 and 0.18 +- 0.11 fm, respectively. These values are compared with results of recent phase-shift analyses and forward dispersion relation calculations.

Inclusive quasielastic {ital {rvec p}}+{sup 2}H analyzing-power and spin-rotation depolarization ({ital D}{sub {ital ij}}) data are reported for the nucleon-nucleon center-of-momentum angular ranges 46.9{degree}--118.0{degree} and 58.3{degree}--110.0{degree} at 647 and 800 MeV, respectively. Exclusive quasielastic {ital {rvec p}p} and {ital {rvec p}n} analyzing-power data and exclusive {ital {rvec p}p} {ital D}{sub {ital ij}} data are also presented. A simple isospin weighting model successfully describes the inclusive data and is used to estimate the free {ital {rvec p}n} {ital D}{sub {ital ij}} values. The new data are compared with those of previous experiments and with predictions of phase-shift analyses. The deduced {ital {rvec p}n} {ital D}{sub {ital ij}} values extend the angular range of previous 800 MeV data and provide entirely new information at 647 MeV.

The cross section, analyzing power, and spin-flip probability have been measured for the M1 transition at 10.23 MeV excitation energy in the /sup 48/Ca(p,p') /sup 48/Ca /sup 48/Ca(p,p') /sup 48/Ca agreement with distorted-wave impulse approximation calculations; about 28% of the pure single particle (..nu..f/sub 7/2/ /sup -1/,f/sub 5/2/)M1 strength is observed. The results serve as a good calibration of results expected in heavy nuclei.

Measurements have been made of the inelastic cross sections and analyzing powers between 2/sup 0/ and 9/sup 0/ for nine 2/sup +/ states in /sup 40/Ca with excitation energies below 10.0 MeV excited by 334-MeV protons. The data can be well described by macroscopic distorted-wave Born-approximation calculations. In general the ..beta..R values deduced from the analysis are in agreement with those obtained by other means. We do not observe a 2/sup +/ state at 6.422 MeV recently reported in a study of the (..gamma..,..gamma..') reaction. A peak at 9.868 MeV is observed which can be described by an L = (0 or 1)+2 admixture. For the L = 2 component (i.e., 2/sup +/ state), we deduce B(E2)arrow-down = 2.0 +- 0.4 e/sup 2/fm/sup 4/.