The spectrum shape and the angular distribution of γ rays from highly excited and rotating ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ and ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$ compound nuclei were measured and analyzed. The results are in good agreement with theory including both intrinsic-shape fluctuations and shape-orientation fluctuations about an equilibrium shape which changes from spherical to oblate deformed with increasing spin.

A recent macroscopic approach to the giant dipole resonances in hot rotating nuclei is extended to include the angular distributions of the γ rays emitted in the resonance decay. It provides a uniform description of thermal fluctuations in all quadrupole shape degrees of freedom within the framework of the Landau theory. In particular, the inclusion of fluctuations in the nuclear orientation with respect to the rotation axis is crucial in reproducing the observed attenuation of the angular anisotropy. The theory is applied to recent precision measurements in ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ and ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$ and is the first to reproduce well both the observed giant-dipole-resonance cross sections and the angular anisotropies.

A measurement of the ${\mathit{K}}^{+}$ total cross sections on carbon and deuterium and their ratios from 450 to 740 MeV/c has been carried out at the Brookhaven Alternating Gradient Synchrotron. The observed ratios depart significantly from those expected from conventional nuclear physics calculations. The data are compared to models of nucleon ‘‘swelling,’’ which ascribe the effect to quark deconfinement or, alternatively, to vector-meson exchange with density-dependent masses.

Two-proton correlation functions measured for the ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$${+}^{27}$Al reaction at E/A=75 MeV are compared to correlation functions predicted for collision geometries obtained from numerical solutions of the Boltzmann-Uehling-Uhlenbeck (BUU) equation. The calculations are in rather good agreement with the experimental correlation function, indicating that the BUU equation gives a reasonable description of the space-time evolution of the reaction.

The first correlation functions from a neutron–light-charged-particle small-angle coincidence measurement are reported for the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{27}$Al reaction at E${(}^{16}$O)=215 MeV. Clear evidence for singlet-deuteron and ${}_{}{}^5{}_{}{}^{}\mathrm{He}$ production, and an anticorrelation of low-relative-momentum neutron-dueteron pairs, is observed. The nuclear temperature of 1.6±0.3 MeV, calculated from the ratio of excited-state to ground-state deuteron emission and corrected for sequential emission, is considerably lower than expected.

The intensities of γ transitions from neutron-resonance states in ${}_{}{}^{169}{}_{}{}^{}\mathrm{Er}$ and ${}_{}{}^{178}{}_{}{}^{}\mathrm{Hf}$ to low-lying states with spin 2–5 are shown to depend on the K values of the final states. This K dependence favors a conclusion that the resonance states can also be associated with good K quantum numbers. The results contradicts the hypothesis that K is completely mixed in this energy region, as expected for a chaotic structure.

Measurements of the vector analyzing power ${\mathit{iT}}_{11}$ in ${\mathrm{\pi }}^{+}$d elastic scattering at 50 MeV have been made at pion laboratory scattering angles between 60° and 130° using a dynamically polarized target and a magnetic spectrometer. In contrast to measurements of spin observables at higher energies, we find agreement with models that include the πN ${\mathit{P}}_{11}$ amplitude and disagreement with models that exclude or suppress it.

Quasielastic (e,e’p) cross sections have been calculated with a full partial-wave expansion of both Coulomb-distorted electron waves and distorted proton waves in the framework of the relativistic σ-ω model. Results are compared with those from currently used nonrelativistic approximations and with data. Spectroscopic factors are derived for the valence-proton knockout of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ and are compared with predictions from recent theoretical approaches.

We calculate the charge response to an electromagnetic field for a homogeneous system of nucleons and pions in the functional framework. This requires dealing with the pion propagation in the medium within the random-phase-approximation scheme. A quenching of the response is obtained in line with the experimental findings. Remarkably, the quenching takes place mainly in the isoscalar channel.

Current data on deep-inelastic processes off nuclei are analyzed by using exact QCD sum rules for the total momentum and baryon charge of nuclei. Evidence for an overall enhancement of the gluon field in heavy nuclei (≥4%) is found which, combined with the calculation of nuclear shadowing, yields a substantial enhancement of valence-quark and gluon distributions at x≊0.1, as well as a suppression of the sea for x≤0.1. It is also shown that scaling violations lead to a strong decrease of shadowing for the sea at x≊0.05. Implications for disentangling the origin of internuclear forces are further discussed.

We have studied (${\mathit{K}}^{\mathrm{-}}$,${\mathit{K}}^{+}$) reactions from an emulsion target. The S=-2 H dibaryon has been searched for by the analysis of the ${\mathit{K}}^{+}$ momentum spectrum together with emulsion data. No evidence of H production was observed in the mass range of 1.90–2.16 GeV/${\mathit{c}}^2$. Upper limits for the production cross section of the H are (0.2–0.6)% of that for the quasifree ${\mathrm{\Xi }}^{\mathrm{-}}$ production at the 90% confidence level.

An internal-target technique was used to make the first measurements of the tensor analyzing power ${\mathit{T}}_{20}$ of electron-deuteron elastic scattering in the four-momentum-transfer range of 2–3 ${\mathrm{fm}}^{\mathrm{-}1}$. Polarized deuterium atoms were confined within a storage cell in the VEPP-3 electron storage ring in Novosibirsk to achieve a total target thickness of 3×${10}^{12}$ ${\mathrm{cm}}^{\mathrm{-}2}$, 15 times greater than was previously possible with an atomic-beam target alone. The results for ${\mathit{T}}_{20}$ are in agreement with reasonable models of the deuteron wave function.

The method of scaled factorial moments is used to study fluctuations of the fragment-size distribution in the percolation model and in nuclear multifragmentation following the breakup of high-energy nuclei in nuclear emulsion. The percolation model accounts well for the fluctuations in the nuclear fragmentation process. An intermittent pattern of fluctuations is found in the data, suggesting a self-similarity in the fragment-size distribution and a random character for the scaling law. However, no evidence of the critical behavior in nuclear multifragmentation is found.

Motivated by a recent measurement of β-delayed fission in the ${}_{}{}^{180}{}_{}{}^{}\to _{}^{180}{}_{}{}^{}$Hg chain, we have calculated the β strength distribution ${\mathit{S}}_{\mathrm{\beta }}$ of the neutron-deficient nuclide ${}_{}{}^{180}{}_{}{}^{}\mathrm{Tl}$ within the framework of the proton-neutron quasiparticle random phase approximation (pn-QRPA). The fission barrier height is then deduced from the measured β-delayed fission probability ${\mathit{P}}_{\mathrm{\beta }\mathrm{DF}}$. In addition, as a test for the reliability of the theoretical strength distributions, ${\mathrm{\beta }}^{+}$/EC half-lives of some isotopic chains are calculated using the pn-QRPA including both particle-hole and particle-particle Gamow-Teller residual interactions.

Four, possibly five, superdeformed bands have been observed in ${}_{}{}^{193}{}_{}{}^{}\mathrm{Hg}$. Two of these bands have strikingly different dynamical moments of inertia from all previously observed superdeformed bands in this region. This behavior can be understood in terms of a level or band crossing. Evidence for transitions between two superdeformed bands is observed for the first time. This, together with the reduced alignments observed and the strong interaction between the crossing bands, is the first experimental evidence supporting the prediction for strong octupole correlations in superdeformed nuclei.

We describe a full nonspurious 4ħω shell-model calculation that successfully reproduces the low-lying spectrum of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, including the superdeformed $0^{+}$ (6.05 MeV) state, and discuss its connection with the coexistence model. This treatment provides a realistic microscopic framework for discussing various electroweak processes: E2 transitions in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, the role of exchange currents and the pseudoscalar coupling constant in the $0^{+}$⇆$0^{\mathrm{-}}$ β-decay and μ-capture transition, and the evaluation of the Gamow-Teller inclusive response function.

A formalism is developed that incorporates parity violation into the statistical theory of nuclear reactions. It allows the calculation of average square values of observables sensitive to parity breaking starting from well known average parameters (transmission coefficients and level densities) as input. For the case of low-energy neutron resonance scattering, a systematic study of the expected size of the effect is presented. An enhanced sensitivity of these reactions to parity violation is borne out.

Optical isotope shifts have been measured in the 5s[3/2${]}_2^0$-5p[3/2${]}_2$ transition in atomic krypton (λ=760 nm) using collinear-fast-beam laser spectroscopy. Isotope shifts were determined for the short-lived neutron-rich isotopes ${}_{}{}^{88}{}_{}{}^{}\mathrm{Kr}$ and ${}_{}{}^{90}{}_{}{}^{}\mathrm{Kr}$, as well as for all the stable isotopes between A=78 and 86, thus extending the data in this element, for the first time, beyond the N=50 shell closure. The deduced changes in the nuclear charge radii show a decrease of the charge radius with increasing neutron number below N=50, and a much more rapid increase above it. A preliminary interpretation of the results is given in terms of the droplet model.

Parity nonconservation was studied for seventeen states in ${}_{}{}^{239}{}_{}{}^{}\mathrm{U}$ by measuring the helicity dependence of the total cross section for epithermal neutrons scattered from ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. The root-mean-squared parity-violating matrix element for the mixing of p-wave and s-wave states was determined to be M=0.${58}_{\mathrm{-}0.25}^{+0.50\mathrm{}}$ meV. This corresponds to a parity-violating spreading width of ${\mathrm{\Gamma }}^{\mathrm{PV}}$=1.0×${10}^{\mathrm{-}7}$ eV. Under plausible assumptions this gives a value of 4×${10}^{\mathrm{-}7}$ for ‖${\mathrm{\alpha }}_{\mathit{P}}$‖, the ratio of strengths of the P-odd and P-even effective nucleon-nucleon interactions.

No evidence of neutron emission was observed following deuterium loading into palladium and titanium in both electrochemical and pressurization experiments. Upper limits obtained with a detector having a very clean neutron signature are at least 100 times lower than values reported in recent publications giving evidence of cold fusion. The deduced fusion rate limits were lower than 2×${10}^{\mathrm{-}26}$ per second per pair of deuterons.