Using a model-space Brueckner-Hartree-Fock approach, we have carried out nuclear matter calculations using the Paris nucleon-nucleon potential. The self-consistent single particle spectrum from this approach is continuous for momentum up to $k_M$, where $k_M$≊2$k_F$ is the momentum space boundary of our chosen model space. The nuclear matter average binding energy and saturation Fermi momentum given by our calculations are ∼15.6 MeV and ∼1.56 ${\mathrm{fm}}^{\mathrm{-}1}$, respectively. When using the conventional Brueckner-Hartree-Fock approach with a spectrum which has a gap at $k_F$, the corresponding results are ∼11.5 MeV and ∼1.50 ${\mathrm{fm}}^{\mathrm{-}1}$. The gain of approximately 4 MeV in binding energy between the two calculations comes mainly from the ${}_{}{}^3{}_{}{}^{}\mathrm{S}_1^{}{}_{}{}^{}$ and ${}_{}{}^1{}_{}{}^{}\mathrm{S}_0^{}{}_{}{}^{}$ partial wave channels. We have investigated the effect of adding an empirical density dependent central potential to the Paris potential. It is found that the addition of such a potential whose strength is ∼10% of the central component of the Paris potential is adequate in making the nuclear matter binding energy and saturation density in simultaneous agreement with the empirical values.

Angular distributions of the differential cross section and analyzing power for the reaction ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(p,${\pi }^{+}$${)}^4$He have been measured at $T_{\mathrm{p}=178\mathrm{}}$ and 198 MeV. The analyzing powers, which have not been measured previously in the near threshold region, are similar to those of the elementary pp→${\pi }^{+}$d reaction at low energies reflecting the dominance of the two-nucleon reaction mechanism.

The ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$(γ,γ’${)\mathrm{}}^{115}$${\mathrm{In}}^{\mathrm{m}}$ photoactivation process was studied by γ-ray irradiation with an intense ${}_{}{}^{60}{}_{}{}^{}\mathrm{Co}$ source. The nonresonant activation of ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$ to the 1078 keV level proposed was reinvestigated. No evidence was obtained for such a direct process but an indirect process of resonance absorption of Compton-scattered γ rays offered a reasonable explanation for the experimental results. Hot atom chemical studies using tris(acetylacetonato) indium(III) as a target material indicated that the excitation of the isomeric level via nonresonant process must be less than 3.3% of the resonance effect.

We compute the magnetic moment of ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ with local Dirac scalar-tensor and vector-tensor interactions that are equivalent to a standard model scalar-vector interaction. We find that using scalar-tensor or vector-tensor interactions brings the calculated magnetic moment substantially closer to its experimental value than using scalar-vector interactions.

A previous calculation of the strong interaction shift of the 1S level in kaonic hydrogen is improved upon and compared to the results of other workers. Good agreement with other calculations—but not with experiment—is obtained.

The effects of strong, short-range attraction in exotic atoms are considered in a simplified model. The model consists of a spherical box of radius b which contains a strong, short-range, real potential well of radius a. Its eigenvalue spectrum has two parts: negative energy, strongly bound ‘‘nuclear’’ states, and positive energy ‘‘atomic’’ states. It is found that the primary effect of the attractive potential on positive energy states is to exclude the wave function from the well. The eigenvalues of these states, identified with experimentally observed atomic states, are thereby shifted upward to the values expected for a smaller box of radius (b-a). Implications for analysis of exotic atom spectra are discussed.

A nuclear system is treated in which a forbidden beta decay leads to a state metastable against gamma-ray emission. Considering both the beta decay and the internal conversion component of the isomeric decay to be accelerated by an applied electromagnetic field, the rate equation for emission from the isomeric state is solved for the case where the nucleus is subjected to alternating episodes of field on and field off. There are important qualitative differences in the solution between the cases where enhancement of the beta transition rate is greater than enhancement of the internal conversion rate, and vice versa. Application is made to the example of ${}_{}{}^{137}{}_{}{}^{}\mathrm{Cs}$.

Inclusive production of neutral pions was observed at $E_{\mathrm{lab}/\mathrm{A}=25\mathrm{}}$ MeV in the reactions ${}_{}{}^{16}{}_{}{}^{}$O+Al,Ni→${\pi }^0$+X. Neutral pions were detected by observing their two decay γ rays in coincidence in an array of 20 Pb-glass Cerenkov-detector telescopes. An array of plastic Cerenkov detectors was added to the above array to tag and reject a significant cosmic-ray background. The observed cross sections are much larger than predicted by nucleon-nucleon collision or statistical models, even if cooperative action of target and projectile nucleons and cluster formation in the final channel are taken into account. This indicates the presence of a collective production mechanism.

The transverse polarization transfer for the ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$(p,n) reaction has been measured for $E_{\mathrm{p}=160\mathrm{}}$ MeV and theta=0°. A sequence of alternating unnatural parity and natural parity excitations is clearly revealed. Some of the observed features are consistent with the known or predicted excitation energies of ΔL=0 and ΔL=1 resonances.

It is shown that a fourth degree SU(3)⊃SO(3) integrity basis interaction, encountered in both fermion and boson theories of nuclear structure, maps onto an axially symmetric rotor Hamiltonian for a special linear combination of the third (LQL) and fourth (LQQL) order scalar operators.

Angular distributions have been measured for ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}(\mathrm{n},\mathrm{n})\mathrm{}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(\mathrm{n},\mathrm{n})\mathrm{}$ at $E_{\mathrm{n}}=30.3\mathrm{} \mathrm{and} 40.3$ MeV. Coupled channels analyses of these and lower energy data have been performed and the resulting potentials compared with those from similar analyses of proton scattering. Data for ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ are also reanalyzed in the same manner. After correcting for purely Coulomb effects, twice the differences between the neutron and proton volume integrals per nucleon of the real potential, $2(J_{\mathrm{n}}-J_{\mathrm{p}}^{\prime })$, are as follows: 0±24 (${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$), -30±11 (${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$), -29±16 (${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$), and 8±14 (${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$) MeV ${\mathrm{fm}}^3$. These results are used to put limits on charge symmetry breaking in the nuclear mean field.

The yields of the (p,γ) and (p,p’γ) reactions on ${}_{}{}^{50}{}_{}{}^{}\mathrm{Cr}$ were measured in the proton energy range 1.7 to 2.5 MeV with an energy resolution <2 keV. In all, 72 resonances were found, mostly in both channels. Nine resonances, at 1.936, 1.942, 2.030, 2.042, 2.113, 2.141, 2.187, 2.303, and 2.408 MeV were determined to be close multiplets. Gamma-ray spectra were measured at 53 resonances, including the multiplets. Angular distributions of the capture γ transitions at 40 resonances and of the $2^{+}$→$0^{+}$ γ transition in ${}_{}{}^{50}{}_{}{}^{}\mathrm{Cr}$ at 27 resonances were measured. The gamma decay schemes of the resonances provided information on 43 excited states of ${}_{}{}^{51}{}_{}{}^{}\mathrm{Mn}$ up to 5.174 MeV. Bound levels at 3.029, 3.835, 3.877, 3.955, 4.006, 4.046, and 4.153 MeV were populated for the first time in the (p,γ) reaction and their decay schemes were determined. Significant revisions of the decay schemes of the 2.276, 2.702, 2.893, 3.131, 3.292, 4.450, 4.540, 5.074, 5.129, and 5.174 MeV levels have resulted from the large number of resonances studied. Spins and parities for many resonances and bound states of ${}_{}{}^{51}{}_{}{}^{}\mathrm{Mn}$ have been determined from an extensive set of angular distribution measurements. In the proton energy range studied, 13 resonances are proposed as isobaric analogs of excited states from 2.704 to 3.207 MeV in ${}_{}{}^{51}{}_{}{}^{}\mathrm{Cr}$.

The analysis of a recent high-resolution neutron capture measurement at 152 m has provided the first evidence that the strong fission resonance at 721 eV is a class-II resonance. This conclusion is based on the measured capture width of 4.7±0.6 meV, which is considerably smaller than the average capture width of 23.5 meV for the neighboring resonances. Furthermore, after analyzing the fission widths for the 721- and 1211-eV clusters, we conclude for the $J^{\pi }={\frac{1}{2}}^{+}$ fission barrier in ${}_{}{}^{239}{}_{}{}^{}\mathrm{U}$ that the inner barrier is lower than the outer barrier by ∼ 1.5 MeV.

The properties of high-spin states in ${}_{}{}^{197}{}_{}{}^{}\mathrm{Bi}$ have been studied with the ${}_{}{}^{192}{}_{}{}^{}\mathrm{Pt}$${(}^{10}$B,5n${)}^{197}$Bi reaction at ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ energies between 50 and 80 MeV. In-beam measurements of γ-ray excitations, γ-γ-t coincidences, γ-ray angular distributions, and pulsed-beam-γ timing were performed with Ge detectors to determine level energies, decay schemes, γ-ray multipolarities, $J^{\pi }$ assignments, and isomeric lifetimes. Yrast levels up to J=(33/2) were established including four isomers. The nuclear structure properties of ${}_{}{}^{197}{}_{}{}^{}\mathrm{Bi}$ are compared with systematic trends for the heavier odd-mass Bi isotopes.

The compound nucleus fluctuation cross section in the intermediate absorption regime of Γ¯/D¯≳1 is discussed within the optical background representation of Kawai, Kerman, and McVoy. A constraining inequality, involving π(Γ¯/D¯), a relevant parameter in the cross section formula, and other statistical parameters that appear in ${{\sigma }_{\mathrm{cc}}^{\mathcal{’}}}^{\mathrm{fl}}$, is derived and analyzed.

Neutrons were measured in coincidence with evaporation residues from the reaction ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$+(300 MeV) ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$. The evaporation residue velocity distribution is indicative of an average transfer of 80% of the full linear momentum in this reaction. The energy spectra of the coincident neutrons exhibit evaporative and preequilibrium components associated with integral multiplicities of $M_{\mathrm{EV}=(9.5\mathrm{}\pm }$0.5) and $M_{\mathrm{PE}=(1.7\mathrm{}\pm 0.3)}$, respectively. The experimental neutron energy and angular distributions are analyzed in terms of multiple-source parametrizations, assuming two or three emitters. The results are compared to those obtained from other inclusive and exclusive associated-particle data. It is observed that the emission patterns of the preequilibrium neutrons are in accord with the predictions of a Fermi-jet model, for neutron angles forward of 35°, while this model fails to reproduce the data at angles in the vicinity of 90° and beyond. Various different nucleon momentum distributions have been employed in the model comparison. The insufficiency of the Fermi-jet model to reproduce the data is attributed to the neglect of two-body collisions in this one-body theory. In contrast, the shape of the angle-integrated preequilibrium-neutron energy spectrum is well reproduced with the Harp-Miller-Berne preequilibrium model, if an initial exciton number of $n_0$=15 is adopted. This value, as well as the preequilibrium neutron multiplicity, is at variance with systematics established previously.

The photon bremsstrahlung spectra from nucleus-nucleus collisions at ultrarelativistic energies are calculated using the proton spectra obtained in a multiple scattering model. At small laboratory angles they are sensitive to the law of stopping when nucleons of one nucleus pass through the other nucleus.

Collective potential energy surfaces are calculated in both the adiabatic and sudden approximations by using the asymmetric two-center shell model in the Strutinsky method. It is shown that fusion of two colliding heavy ions occurs by their crossing over of the adiabatic interaction barrier. The adiabatic scattering potentials present two barriers, whereas no barrier is shown to occur in sudden scattering potentials. The first barrier is obtained just past the saddle shape but is too low, such that a deep inelastic process is expected. The other, inner, barrier is high enough to let the system fall into the fusion well, whose excitation energy then determines whether a cool compound nucleus is produced or the fusion-fission process occurs. For a given compound nucleus, the excitation energy is found to be small for only a few target-projectile combinations, which increase as their mass asymmetry increases. Such target-projectile combinations which refer to a cool compound nucleus can be identified by a simple calculation of the fragmentation potential based on the ground state binding energies with Coulomb and proximity effects calculated at a constant relative separation of the two nuclei. Our calculations are made for the composite systems with 102≤Z≤114.

The reaction of ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$ with Ta at 20 MeV/nucleon has been observed to produce pairs of complex projectile-like fragments. These fragments are emitted far from the target following the stripping of nucleons from the projectile to form an excited primary ejectile. The inelasticity of the reaction with the target is midway between a fully damped and a quasi-elastic collision. The spectra of relative fragment energies agree with an equilibrated distribution of excitation energy in the primary ejectile, thus supporting the hypothesis that the fragments are the products of a statistical decay process.

Values of deformation parameters have been extracted from macroscopic coupled-channels analyses of inelastic proton scattering to the first $2^{+}$, $3^{\mathrm{-}}$, and $4^{+}$ states of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ 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.