A multienergy phase shift analysis of all published proton-proton (pp) scattering data in the energy range $T_{\mathrm{lab}\mathrm{\le }30}$ MeV is presented. In the description of all partial waves the well-known long-range interaction is included: the improved Coulomb, the vacuum polarization, and the one-pion-exchange potential. In the lower partial waves the energy-dependent analysis uses a P-matrix parametrization for the short-range interaction. Special attention is paid to the electric interaction, the definition of the phase shifts, and the selection of the data. The fit to the final data set comprising 360 scattering observables results in ${\chi }^2$/$N_{\mathrm{df}=1.0\mathrm{}}$, where $N_{\mathrm{df}}$ is the number of degrees of freedom. The pp${\pi }^0$ coupling constant is determined to be ${\mathit{g}}_{\mathrm{pp}}$${\mathrm{\pi }}_{{}_{}{}^2{}_{}{}^{}}^0$/4π=14.5±1.2, but there are several indications for a lower value. The optimum value for the P-matrix radius b≊1.4 fm is satisfying. Single-energy phase shifts with second derivative matrices, and effective range parameters are given.

Measurements of the production cross sections and angular distributions of high energy γ rays from the reaction of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ with ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ with ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$ at a bombarding energy $E_{\mathrm{proj}/\mathrm{n}\mathrm{u}\mathrm{c}\mathrm{l}\mathrm{e}\mathrm{o}\mathrm{n}=15\mathrm{}}$ MeV are reported. Gamma rays in the energy region of 10 to 30 MeV were observed in a set of bismuth germanate scintillators. A large component of known γ-ray transitions in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ nuclei near 15 MeV dominated the γ-ray spectra from the ${}_{}{}^{12}{}_{}{}^{}$C${+}^{12}$C system. The spectra were fit with a combination of the discrete lines (using the calibrated response function of the BGO detectors) and an underlying exponential distribution of γ rays. The γ-ray spectra observed in the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ti}$ reaction were similar but lacked the discrete lines. The fitted parameters are compared to the results of previous studies of high energy γ-ray production.

Energy and angular distributions of neutrons emitted from collisions of 35 MeV/nucleon ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ ions with carbon, nickel, and holmium nuclei were measured. The neutrons were in coincidence with Li, Be, B, or C fragments at angles from 7° to 23° in the plane of the neutron detectors and at 15° out of this plane. Using fragment velocity bins of width corresponding to E/A=7 MeV, we find the shapes of the neutron spectra above 15 MeV to be similar for the different targets for a given coincident fragment species, velocity bin, and angle. The cross sections are discussed in terms of moving thermal sources. In all cases the velocity and temperature parameters of the intermediate rapidity source are consistent with E/A=8.5±2.5 MeV and T=9±2.5 MeV, respectively. In agreement with a simple stripping-pickup model, the associated neutron multiplicities of this source decrease approximately linearly with the velocity of the coincident light fragments for fragment angles ≤15°. Using the model to compute the mass of the source, we find that, with some fluctuations, these multiplicities are proportional to the mass. Also, the linear relationship is approximately the same for the three targets. The temperature parameters of the target-like source are between 1 and 3.5 MeV for all three targets, while the associated neutron multiplicities increase considerably with target mass. For colinear neutron-fragment coincidences for a given projectile-like isotope, the neutron multiplicities associated with the projectile-like source are about the same for all three targets, indicating that the average excitations of the parent fragments are similar.

Using the expanding fireball model, we calculate the $K^{+}$/${\pi }^{+}$ ratio from heavy-ion collisions at 14.5 GeV/nucleon. A substantially larger ratio than that from the proton-nucleus collisions at the same energy is obtained if the contribution from the pion-pion interactions is included. This is supported by the preliminary data.

Inclusive neutron spectra were measured at 0° from Nb-Nb and Au-Au collisions at 800 MeV/nucleon. The spectra in the rest frame of the projectile were decomposed into three Gaussians with standard deviations of 55±4, 114±12, and 259±22 MeV/c for Nb-Nb collisions, and 56±4, 110±10, and 279±15 MeV/c for Au-Au collisions. Physical processes associated with each Gaussian are discussed. The dependence of the parameters of the three Gaussians on the impact parameter indicates that the temperature of the spectators excited by peripheral collisions is lower than that excited by nonperipheral collisions, that projectile neutrons involved in nonperipheral collisions have a broader momentum distribution than those involved in peripheral collisions, and that an observed high-energy tail has its origin primarily in nonperipheral collisions. The high-energy tail is explained well by collective backscattering of neutrons in the target from nucleon clusters in the projectile with a mean cluster size of about 1.3 in both Nb and Au.

Nuclide distributions have been measured for damped collision products formed in the reaction of E/A=8.5 MeV ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ and ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$ ions with ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. The data demonstrate that in these very asymmetric systems the evolution of the nucleon-exchange process as a function of energy loss depends strongly on the N/Z value of the projectile and the corresponding gradient in the potential-energy surface. Comparison of the data with transport model calculations shows qualitative agreement with the N and Z centroids, variances, and correlation coefficients. However, absolute discrepancies exist which suggest the need for improvement in the model.

The cross section for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^{139}$La,X${)}^{11}$C reaction was measured using 1.26-GeV/nucleon ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$ ions. Annihilation radiation from the decay of ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ was counted using a large volume NaI(Tl) detector. The resulting cross section for ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$ was 147.9±2.0 mb. The results are compared with similar measurements using relativistic ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, and ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ projectiles and the predictions of a linear transport model.

A unified theory of photopion reactions in two-nucleon systems (γd→pn, ${\pi }^0$d, and πNN) and NN bremsstrahlung (NN→NNγ) is presented. By exposing the two-body [BB, where B=N or Δ(1232)] and three-body (πBB and γBB) unitarity, we derive a set of coupled integral equations to determine the amplitudes for these reactions. These equations have the same kernel as the equations one gets for the BB-πBB system. The two-body input amplitudes are the result of a coupled channel unitary theory for πN→πN and pion photoproduction on a single baryon, within the framework of a gauge and chirally invariant Lagrangian, which is obtained from the chiral bag model Lagrangian. The renormalization due to the πB interaction is incorporated in a consistent manner.

Cross sections and analyzing powers for ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ at 250 MeV and for ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ at 200 and 250 MeV, and cross sections for ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ at 400 MeV are presented for elastic scattering and inelastic scattering to the low-lying $2^{+}$ state in each nucleus. The data are compared to ‘‘consistent’’ microscopic distorted-wave impulse approximation calculations in both relativistic and nonrelativistic models. The calculations presented here give a good description of the data. For comparison, calculations are also presented for previously published data on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at 200, 250, and 400 MeV.

Angular distributions of charge asymmetry A($T_{\pi }$,θ), have been measured for πd elastic scattering. Data were obtained in the backward hemisphere for pion bombarding energies of 143, 180, 220, and 256 MeV. The results are compared with predictions employing different mass and width parameters for the delta isobars.

Angular distributions of the tensor analyzing powers $T_{20}$ and ${\tau }_{21}$ have been measured for πd elastic scattering, in a single scattering experiment employing a tensor polarized deuteron target. Measurements of $T_{20}$ were obtained for pion bombarding energies of 134, 151, 180, 220, and 256 MeV. Measurements of ${\tau }_{21}$ were obtained for pion bombarding energies of 134, 180, and 220 MeV. The results are compared with three-body calculations where effects relating to pion absorption are seen to play an important role.

Integral recoil properties of 25 nuclides produced in the interaction of 800 MeV p${+}^{89}$Y were determined using activation techniques. The forward-to-backward recoil ratios are a factor of 3 larger for n-deficient products compared to near-stable and n-excess products of similar mass, a behavior not discovered in previous studies. The results are interpreted as an indication that the near-stable and n-excess products, previously assumed to be the result of conventional N-N intranuclear cascades, actually reflect a significant contribution from ‘‘target fragmentation’’ channels.

Based on the Lagrangian of Olsson and Turner, contributions of the second kind of meson exchange current to pion-nucleus double-charge-exchange reactions ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$(${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^{\mathrm{-}}$${)}^{18}$${\mathrm{N}}_{\mathit{e}\mathrm{}(\mathrm{g}.\mathrm{s}))}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^{\mathrm{-}}$${)}^{14}$${\mathrm{O}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ have been evaluated. The calculated results show that the second kind of meson exchange current makes the forward theoretical cross section closer to the experimental data but the long-standing puzzling problem of the location of the minimum of the angular distribution at the energy of 164 MeV has not been solved.

Gamow-Teller β decay of ${}_{}{}^{80}{}_{}{}^{}\mathrm{Zn}$ to levels in ${}_{}{}^{80}{}_{}{}^{}\mathrm{Ga}$ has been calculated from a random-phase-approximation shell model with Nilsson model wave functions. The predicted features are compared to existing experimental results. Gross β-decay properties as well as quasiparticle structure indicate shape coexistence for ${}_{}{}^{80}{}_{}{}^{}\mathrm{Ga}$. This result implies a rather rapid weakening of the shell strength far from β stability above ${}_{28}{}^{78}{}_{}{}^{}\mathrm{Ni}_{50}^{}{}_{}{}^{}$. The nuclear properties of ${}_{}{}^{80}{}_{}{}^{}\mathrm{Zn}$ as an astrophysical ‘‘waiting-point’’ nucleus suggest that the r-process scenario which is responsible for the solar r abundances has attained an (n,γ)-(γ,n) equilibrium.

The first information obtained on excited states of the N=50 isotone ${}_{}{}^{83}{}_{}{}^{}\mathrm{As}$ populated in the β decay of neutron-rich ${}_{}{}^{83}{}_{}{}^{}\mathrm{Ge}$ is presented. The ${}_{}{}^{83}{}_{}{}^{}\mathrm{Ge}$ half-life was measured to be 1.85±0.06 s. Using γ singles and γγ coincidence measurements, a total of 51 γ rays were placed in a level scheme for ${}_{}{}^{83}{}_{}{}^{}\mathrm{As}$ corresponding to 28 levels in a range of excitation energy up to 4.84 MeV. The density of levels up to 2.0 MeV excitation energy is reasonably well reproduced by shell-model calculations, indicating that ${}_{}{}^{78}{}_{}{}^{}\mathrm{Ni}$ is probably a doubly magic nucleus. Approximately half of the β intensity to excited states in ${}_{}{}^{83}{}_{}{}^{}\mathrm{As}$ populates a group of levels above 3.5 MeV excitation energy which can be interpreted as primarily core polarization neutron particle-neutron hole states.

The branching ratio between internal electromagnetic transitions and ${\beta }^{\mathrm{-}}$ decays of the isomer ${}_{}{}^{79\mathrm{m}}{}_{}{}^{}\mathrm{Se}$ was determined experimentally. Extremely clean samples of ${}_{}{}^{78}{}_{}{}^{}\mathrm{Se}$ were activated with thermal neutrons at a high-flux reactor. A mini-orange-Si (Li) detection system was used to measure ${\beta }^{\mathrm{-}}$ particles and conversion electrons immediately after neutron irradiation. For the ${\beta }^{\mathrm{-}}$ decay we obtain logft${=4.70\mathrm{}}_{\mathrm{-}0.09}^{+0.10\mathrm{}}$. Our present result was used to recalculate the temperature dependence of the effective ${\beta }^{\mathrm{-}}$ half-life of ${}_{}{}^{79}{}_{}{}^{}\mathrm{Se}$ in the stellar interior. In combination with the half-life deduced from a quantitative branching analysis, we obtain a possible temperature range between 182 and 295 million degrees for the weak component of the s process.

The level structure of ${}_{}{}^{143}{}_{}{}^{}\mathrm{La}$ has been investigated by measurement of gamma-ray and conversion-electron singles, gamma-gamma coincidence, and gamma-gamma angular correlation spectra following the decay of 15.0-s ${}_{}{}^{143}{}_{}{}^{}\mathrm{Ba}$. Comparison of the observed structure of ${}_{}{}^{143}{}_{}{}^{}\mathrm{La}$ with the structures of isotopic La and isotonic N=86 nuclides, as well as those of the adjacent Cs isotopes and N=84 isotones, suggests the presence of unusual low-lying ${(3/2\mathrm{}}^{+}$ and ${(5/2\mathrm{}}^{\mathrm{-}}$ levels that are not readily accounted for by theoretical calculations. The observed structures suggest that the deformation in this mass region is influenced by different factors than that of the nuclides above Z=64, and that reflection asymmetric structures play an important role in the structure of the nuclides in the A=145 mass region.

In view of recent experimental data on g factors of osmium isotopes which show interesting variations as a function of mass number as well as spin, we have calculated these following the methods of variation after exact angular momentum projection of axial Hartree-Fock-Bogoliubov wave functions and the cranked Hartree-Fock-Bogoliubov theory. The observed trend of the variation of g factor at I=2 with the mass number A=186–192 is reproduced with very minor adjustments of the force constants of the employed pairing-plus-quadrupole model Hamiltonian in both the approaches. However, the variation of g factor with spin, which is sensitive to the interplay between collective and single particle degrees of freedom, can be understood only in the cranking approach. Though these nuclei are prolate in shape, with the increase of A they become more and more γ soft and we suggest that γ deformation should be treated in a generator coordinate type of calculation.

The low-density expansion of the ground-state energy for spin-dependent forces is given, through order $k_F^6$ for the ladder approximation and through order $k_F^6$ln$k_F$ for the complete energy, in terms of derivatives with respect to the strength of the attractive part of the interaction defined by the Baker-Hind-Kahane potential. The ladder approximation is also computed by the numerical solution of the K-matrix equation. The resulting series gives a satisfactory representation of the energy at interesting densities. Using Padé extrapolation techniques, both in the density and in the attractive part of the interaction, we obtain the ground-state energy of nuclear matter.

We present a systematic study of transverse current multipoles of the ground-state band in even-even rare-earth nuclei. We analyze the q dependence of the form factors under different assumptions about the nature of the rotational mode. We show and compare numerical results of projected-Hartree-Fock and cranking model calculations for ${}_{}{}^{154}{}_{}{}^{}\mathrm{Sm}$, ${}_{}{}^{156}{}_{}{}^{}$,158Gd, ${}_{}{}^{164}{}_{}{}^{}\mathrm{Dy}$, ${}_{}{}^{166}{}_{}{}^{}$,168Er, and ${}_{}{}^{174}{}_{}{}^{}\mathrm{Yb}$. We discuss the dependence of the multipoles on the mean field used to generate the ground-state wave function. Finally, we compare to predictions of the rigid rotor and irrotational fluid flow models. Comparison to experiment is restricted to very low momentum transfer by lack of relevant data.