We have measured the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(parrow,${\gamma }_0$${)\mathrm{}}^{13}$N in the energy region of the $E_{\mathrm{p}=1.7\mathrm{}}$ MeV resonance and applied R-matrix theory to its analysis. We used the strong interaction form of the theory where the wave function in the internal region is represented entirely in terms of compound nucleus formation. In order to account fully for the data, an extranuclear direct capture background was found to be necessary, but no internal background was needed.

Measurements of angular distributions of the cross sections and analyzing powers for the elastic and inelastic scatterings of 65 MeV polarized protons from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, and ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ are reported. Coupled channels analyses of the scattering data are presented assuming the $0_1^{+}$, $2_1^{+}$, and $4_1^{+}$ states to be members of the ground band, the $0_2^{+}$ state to begin the

β band, and the $3_1^{\mathrm{-}}$ state to begin the $K^{\pi }$${=3\mathrm{}}^{\mathrm{-}}$ band in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$; the $0_1^{+}$, $2_1^{+}$, and $4_1^{+}$ states to comprise the ground band, the $2_2^{+}$, $3_1^{+}$, and $4_2^{+}$ states to comprise the γ band, the $3_1^{\mathrm{-}}$ state to begin the $K^{\pi }$${=3\mathrm{}}^{\mathrm{-}}$ band, and the $1_1^{\mathrm{-}}$ and $3_2^{\mathrm{-}}$

states to comprise the $k^{\pi }$${=0\mathrm{}}^{\mathrm{-}}$ band in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$; and the $0_1^{+}$, $2_1^{+}$, and $4_1^{+}$ states to comprise the ground band, the $0_2^{+}$ state to begin the β band, the $3_1^{\mathrm{-}}$, $4_1^{\mathrm{-}}$, $5_1^{\mathrm{-}}$, and $6_1^{\mathrm{-}}$ states to comprise the $k^{\pi }$${=3\mathrm{}}^{\mathrm{-}}$ band, and the $1_1^{\mathrm{-}}$

and $3_1^{\mathrm{-}}$ states to comprise the $K^{\pi }$${=0\mathrm{}}^{\mathrm{-}}$ band in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$. The fit of the analyzing power of the β band $0_2^{+}$ level is improved by mixing the breathing mode of oscillation into the β vibration. Coupled channels analyses of the experimental angular distributions are presented for the levels in ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ in which the $0_1^{+}$, $2_1^{+}$, and $4_1^{+}$ states were assumed to belong to the ground band, the $0_2^{+}$ and $2_3^{+}$ states to the β band, the $2_2^{+}$, $3_1^{+}$,

and $4_2^{+}$ states to the γ band, the $3^{\mathrm{-}}$ state to the $3^{\mathrm{-}}$ band, and the $1^{\mathrm{-}}$ state to the $0^{\mathrm{-}}$ band. These states were treated assuming a symmetric rotator model. The coupled channels calculations in terms of a vibrational model were also performed for ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$. Multipole moments obtained from present data are compared to the moments deduced from hadron scattering and electromagnetic measurements. Transition strengths deduced from the (p,p’) scattering are compared with gamma-ray decay widths for $2^{+}$ states in the ground bands.

The differential cross section for the ${}_{}{}^{16}{}_{}{}^{}(\gamma$,p${)}^{15}$N process has been measured in the energy range $E_{\gamma }$=100–400 MeV at laboratory angles of 45°, 90°, and 135°. The cross sections for the (γ,p) reaction leaving ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ in its ground state, in its first and second excited states at $E_x$≊5.3 MeV, and in its third excited state at $E_x$=6.3 MeV were extracted from the tip region of the proton spectra measured at a series of bremsstrahlung end point energies. The data are compared with calculations based on a direct, single-particle knockout mechanism and on mechanisms involving two particles in an intermediate state.

Inelastic alpha scattering measurements have been performed for ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ at small angles including zero degrees. A total of 66% of the E0 energy-weighted sum rule was identified (using a Satchler version 2 form factor) centered at $E_x$=17.9 MeV having a width of 4.8 MeV and 34% of the E2 energy-weighted sum rule was identified above $E_x$=15.3 MeV centered at 19.0 MeV with a width of 4.4 MeV. The dependence of the extracted E0 strength on form factor and optical potential was explored.

A polarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ target, which uses conventional optical pumping with ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ discharge lamps, has been used for the measurement of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ analyzing powers $A_y$(θ) at energies of 25.0, 30.0, 32.5, and 35.0 MeV. The statistical uncertainties in the data are on the order of 0.03; the systematic uncertainty is estimated to be 0.05. These data are compared with fits and predictions from various phase shift analyses.

In ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, the isovector M2 strength distribution in the excitation region of $E_x$=11–24 MeV was investigated by inelastic electron scattering. Two transitions to levels at $E_x$=11.62 and 12.1 MeV were observed with strengths of B(M2,k)↑=64±13 and 56±13 ${\mu }_{\mathrm{N}}^2$${\mathrm{fm}}^2$, respectively. A comparison with the analogous (${\pi }^{\mathrm{-}}$,γ) reaction shows that orbital contributions are non-negligible in these transitions. The data are compared to model predictions.

The (p,pα) cluster knockout reaction on ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ was investigated using polarized incident protons. Coincident data for eight quasifree angle pairs were obtained at a bombarding energy of 150 MeV. Both differential cross sections and analyzing powers were measured for the energy-sharing distribution. Distorted wave impulse approximation calculations indicate that the reaction is dominated by a quasifree knockout process, and that a D-state component of the cluster-core wave function is important for larger momentum transfer. Extracted absolute spectroscopic factors for both S- and D-state knockout are in good agreement with theoretical predictions. The analyzing power follows the trend of free p${\mathrm{-}}^4$He scattering and agrees with the distorted wave impulse approximation calculation reasonably well. Near zero recoil momentum, the spin-orbit interaction in the distorted waves plays little role.

The polarization transfer parameter $D_t$(180°) for n-p scattering has been measured at 50 MeV for the first time. Polarized neutrons produced in the ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(darrow,narrow${)\mathrm{}}^3$He reaction were scattered from the hydrogen in a polyethylene target and the polarization of the recoil protons emitted at 0° was measured in a carbon polarimeter. The result of this measurement tests the prediction of $D_t$ from a phase shift analysis of the N-N data and that of a theoretical proposal concerning n-p charge exchange.

New data are presented for the ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$(p,n${)}^{11}$C reaction taken at 1 MeV intervals for proton bombarding energies in the $E_{\mathrm{p}=16\mathrm{}–}$26 MeV range. In the experiment, final states in ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ up to $E_x$≃10 MeV were clearly identified and differential cross sections were extracted for the first four levels in ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$. The $E_{\mathrm{p}=26\mathrm{}}$ MeV data are examined in microscopic distorted-wave approximation calculations using the wave functions of Cohen and Kurath to describe the states in ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$ and ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ and using the G matrix interaction of Bertsch et al. for the effective nucleon-nucleon interaction. Gamow-Teller matrix elements for transitions to excited states in ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ are extracted on the basis of these calculations, thus extending the information on Gamow-Teller matrix elements in the mass 11 systems beyond the ground state matrix element known from β decay. Throughout, the results are contrasted with existing information from electromagnetic studies of ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$. It is concluded that the Cohen-Kurath model places too much Gamow-Teller strength in the low lying states of the mass 11 systems and not enough strength at higher excitation energies. In addition, this model underestimates the net contribution to M1 matrix elements from the isoscalar spin and current and isovector current parts of the M1 operator.

The structure of $5^{\mathrm{-}}$, $6^{\mathrm{-}}$, and $7^{\mathrm{-}}$ yrast states in ${}_{}{}^{68}{}_{}{}^{}\mathrm{Zn}$ has been studied through the reaction ${}_{}{}^{67}{}_{}{}^{}\mathrm{Zn}$(d,p${)}^{68}$Zn at $E_{\mathrm{d}}$=6 MeV. The spectroscopic factors in the (d,p) reaction strongly suggest that these negative-parity states are not rotational states, but spherical two-quasiparticle states with ν(1$f_{5/2}$1$g_{9/2}$${)}^{J=5\mathrm{}}$,6, 7 configurations. The possible low-spin members with ν(1$f_{5/2}$1$g_{9/2}$${)}^{J=2\mathrm{}}$,3, 4 configurations have been observed in the present reaction. Spectroscopic factors and l values for 36 levels have also been extracted by angular distribution measurements.

Inelastic electron scattering from ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ has been performed over a momentum transfer range from 0.6 to 3.0 ${\mathrm{fm}}^{\mathrm{-}1}$ 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 ν(1$g_{9/2}$,1$f_{7/2}^{\mathrm{-}1}$${)}_8$ ${}_{}{}^{\mathrm{-}}{}_{}{}^{}$ but with a total strength of only 36% predicted for the first $8^{\mathrm{-}}$ 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.

In an attempt to study isovector spin-flip excitations and to find a consistent picture of giant resonances in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, we analyzed giant resonance data from 172 MeV α scattering, 140 MeV ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ scattering, and 200 MeV proton scattering. Using spectroscopic information from α scattering, a good description of recent ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ scattering data is obtained. A detailed analysis of results from different probes reveals differences between complex particle and proton spectra which are interpreted as due to spin-flip contributions. The spin-flip strength is estimated in a microscopic p-h model. At the scattering angles considered it gives resonant strength at ∼9 MeV dominated by $2^{\mathrm{-}}$ excitations and further gives an increasing continuum yield towards higher excitation energies. The cross sections of these spin-flip excitations in (p,p’) are comparable to giant resonance yields and have to be considered in order to obtain a description consistent with complex particle spectra. The continuum part of isoscalar excitations is rather different from that of isovector spin-flip excitations. These features are qualitatively understood from the nuclear matter response. Calculations using the semi-infinite nuclear slab model of Esbensen and Bertsch give an almost quantitative description of isoscalar and spin-isospin continuum.

Six low-lying negative parity levels of ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$, up to 688.5 keV excitation energy, were observed to be Coulomb excited with 4.32 MeV protons. Eleven deexcitation transitions from these levels were identified in the singles gamma-ray spectra recorded with a 57 ${\mathrm{cm}}^3$ Ge(Li) detector. The 515.5, 566.8, 638, and 688.5 keV levels have been Coulomb excited with protons for the first time. Level energies, branching ratios, B(E2) transition probabilities, and the multipole mixing ratios (δ) were obtained. Existing ambiguities in the reported measurements of B(E2) were resolved. The angular distributions of the nine deexcitation transitions were analyzed to extract the angular distribution coefficients $A_2$, and the δ values for the mixed 115.1, 543.3, 566.8, and 593.8 keV transitions. The results have been discussed in light of the previously reported results.

Reactions between heavy ions at medium energy are calculated using the Boltzmann-Uehling-Uhlenbeck equation. This equation incorporates the effects of a mean field as well as Pauli blocking of the nucleon-nucleon collisions. The numerical solution for two light systems, ${}_{}{}^{16}{}_{}{}^{}$O${+\mathrm{}}^{12}$C at 25back20A MeV bombarding energy and ${}_{}{}^{12}{}_{}{}^{}$C${+\mathrm{}}^{12}$C at 84back20A MeV bombarding energy, is presented and discussed in detail. In the absence of nucleon-nucleon collisions, the theory reduces to classical mean-field physics and agrees well with the quantal time-dependent Hartree-Fock theory. With collisions, the system is driven toward equilibrium even at the lower bombarding energy. The final state nucleon distribution is compared to single-particle spectra and is found to agree quite well in shape.

We carry out a numerical simulation of the hydrodynamic evolution of a cylindrically symmetric quark-gluon plasma of finite extent, as formed in a central collision of two identical ultrarelativistic heavy ions, assuming inviscid flow with Lorentz-invariant initial conditions within the plasma and an ideal gas equation of state. For the central collisions of ${}_{}{}^{238}{}_{}{}^{}$U${+\mathrm{}}^{238}$U at a center-of-mass energy of 30 GeV per nucleon, the critical temperature for hadronization is reached just 1.5 fm/c after the onset of hydrodynamic expansion, at which time the expansion is still predominantly longitudinal.

Angular distributions for the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$${(}^6$Li${,}^6$He) charge exchange reaction, ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$${(}^6$Li${,}^6$Li) elastic and inelastic scattering, and the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$${(}^6$Li${,}^7$Li) transfer reaction have been measured at E=32 MeV. Limited measurements at 36 MeV showed no change in the cross sections at this energy compared with those at 32 MeV. Coupled channels calculations are necessary to describe the inelastic scattering data to the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, 2.43 MeV, ${\mathrm{}(5/2)\mathrm{}}^{\mathrm{-}}$ state. The deformation length obtained is in good agreement with the electron scattering value. A microscopic analysis of the charge exchange reaction shows that the M3Y interaction gives a good description of the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ ground state to ${}_{}{}^9{}_{}{}^{}\mathrm{B}$ ground state transition, but underpredicts the cross section to the ${}_{}{}^9{}_{}{}^{}\mathrm{B}$, 2.36 MeV, ${\mathrm{}(5/2)\mathrm{}}^{\mathrm{-}}$ state by a factor of 3. The same calculations carried out for previously reported ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$${(}^6$Li${,}^6$He) data reproduce the magnitude of the data provided that Visscher-Ferrell densities are used for the ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ to ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ transition. The results of finite range distorted-wave Born approximation calculations for ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$${(}^6$Li${,}^7$${\mathrm{Li}}_0$,1) ${}_{}{}^8{}_{}{}^{}$${\mathrm{Be}}_0$ show the neutron pickup spectroscopic factors to be in good agreement with the Cohen-Kurath calculations.

Gamma ray multiplicities and the (HI,xn) cross sections for the dominant reaction channel were measured at near-barrier bombarding energies for the systems α${+\mathrm{}}^{154}$Sm and ${}_{}{}^{12}{}_{}{}^{}$C${+\mathrm{}}^{154}$Sm. The mean value of the spin distribution of the compound nucleus was obtained for each of the systems studied. The results of these measurements together with the results of an earlier study on ${}_{}{}^{16}{}_{}{}^{}$O${+\mathrm{}}^{154}$Sm indicate that at bombarding energies near and below the Coulomb barrier the spin distributions of the compound nucleus are broader than the triangular distributions expected from a sharp cutoff model, these deviations being larger for the more massive projectiles. The different behavior of the three systems clearly indicates the importance of the centrifugal barrier penetrability in determining the spin distribution of the compound nucleus. The absolute values of the mean angular momentum can be accounted for if one also includes deformation effects. A one-dimensional barrier-penetration model including the effect of averaging over the orientation of the deformed target can account for the experimental results.

Excitation functions have been measured for production of isotopes of Bk through Fm in bombardments of ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$ with 234- to 294-MeV ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ ions and with 239- to 318-MeV ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ ions. The maxima of the isotopic distributions for these elements occur at only 2 to 3 mass numbers larger for ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ than for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ reactions. The shapes of the distributions and the half-widths of about 2.5 mass numbers are quite similar to those observed previously for reactions of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, and ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$ with ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$. In general, the excitation functions for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ show maxima near the Coulomb barrier while those for ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ are about 20 MeV above the barrier. The cross sections decrease rather slowly with increasing projectile energy over the energy range studied, indicating that the additional projectile energy is not manifested as excitation energy of these actinide products.

The role of nonequilibrium and quantal effects in fast nucleus-nucleus collisions is studied via the Vlasov-Uehling-Uhlenbeck theory which includes the nuclear mean field dynamics, two-body collisions, and Pauli blocking. The intranuclear cascade model, where the dynamics is governed by independent NN collisions, and the Vlasov equation, where the nuclear mean field determines the collision dynamics, are also studied as reference cases. The Vlasov equation (no collision term) yields single particle distribution functions which–after the reaction–are only slightly modified in momentum space; even in central collisions, transparency is predicted. This is in agreement with the predictions of the quantal time-dependent Hartree-Fock method. In contrast, large momentum transfer is obtained when the Uehling-Uhlenbeck collision term is incorporated; then the final momentum distribution is nearly spherically symmetric in the center of mass and a well-equilibrated nuclear system is formed: the nuclei stop each other; the translational kinetic energy is transformed into randomized microscopic motion. The Vlasov-Uehling-Uhlenbeck theory is supplemented with a phase space coalescence model of fragment formation. Calculated proton spectra compare well with recent data for Ar(42, 92, and 137 MeV/nucleon) + Ca. Also the total yields of medium mass fragments are well reproduced in the present approach. The mean field dynamics without two-body collisions, on the other hand, exhibits forward peaked proton distributions, in contrast to the data. The cascade approach underpredicts the yields of low energy protons by more than an order of magnitude.

Excitation functions have been measured at 0° and 180° for the ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$${(}^{16}$O${,}^{12}$C${)}^{28}$ Si(g.s.) reaction, and at 180° for the ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$${(}^{16}$O${,}^{12}$C${)}^{28}$ Si($2^{+}$) reaction over the energy range 36 MeV≤$E_{\mathrm{c}.\mathrm{m}.\mathrm{}}$≤54 MeV. Angular distributions were measured at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}$=35.5 and 36.2 MeV where, for the latter energy, much of the angular range between 0° and 180° was covered. These data, combined with earlier measurements at lower energies, establish that the reaction cross section is strongly influenced by resonances of the compound system over a large energy range. At the higher energies, however, both the energy averaged cross section and the resonance amplitudes fall off sharply. An attempt is made to reproduce the observed structure in the ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$(g.s.) 0° and 180° excitation functions by fitting to the data a band of Breit-Wigner resonances with an energy dependence proportional to J(J+1). The general behavior of the 0° and 180° yield is well reproduced by this procedure, even though there are twice as many resonance poles as there are clear bumps in the data. Some regularity is evident in the resulting resonance parameters, although the fitted resonance amplitudes show greater scatter than expected for a nuclear molecular band.