Single-particle overlap functions and spectroscopic factors are calculated on the basis of the one-body density matrices (ODM) obtained for the nucleus ${}^{16}\mathrm{O}$ employing different approaches to account for the effects of correlations. The calculations use the relationship between the overlap functions related to bound states of the $\left(A-1\right)$-particle system and the ODM for the ground state of the A-particle system. The resulting bound-state overlap functions are compared and tested in the description of the experimental data from $\mathrm{}(p,d)\mathrm{}$ reactions for which the shape of the overlap function is important.

An extended version of the nonlinear Walecka model, with $\rho$ mesons and electromagnetic field is used to investigate the possibility of phase transitions in hot (warm) nuclear matter, giving rise to droplet formation. Surface properties of asymmetric nuclear matter as the droplet surface energy and its thickness are also examined. The effects of the Coulomb interaction are discussed.

Using effective meson Lagrangians we study the interaction of $\rho$ mesons in a hot baryon-free system. Various mesonic resonances in direct s-channel reactions are investigated employing standard self-energy techniques, including new reactions that have up to now not been considered in a self-consistent approach at finite temperature. The importance of subthreshold resonances, which are readily accounted for through off-shell effects within our framework, is emphasized. Special care is taken in reproducing radiative decay widths, as they provide valuable constraints on the evaluation of dilepton spectra. In particular, we compare our results for dilepton production rates to earlier calculations based on an incoherent summation of individual processes.

The assumption of local equilibrium in relativistic heavy ion collisions at energies from $10.7A$ GeV (AGS) up to $160A$ GeV (SPS) is checked in the microscopic transport model. Dynamical calculations performed for a central cell in the reaction are compared to the predictions of the thermal statistical model. We find that kinetic, thermal, and chemical equilibration of the expanding hadronic matter are nearly approached late in central collisions at AGS energy for $t>~10\hspace{0.5em}\mathrm{fm}/c$ in a central cell. At these times the equation of state may be approximated by a simple dependence $P\cong (0.12\mathrm{}-0.15)\varepsilon$. Increasing deviations of the yields and the energy spectra of hadrons from statistical model values are observed for increasing energy, $40A$ GeV and $160A$ GeV. These violations of local equilibrium indicate that a fully equilibrated state is not reached, not even in the central cell of heavy ion collisions at energies above $10A$ GeV. The origin of these findings is traced to the multiparticle decays of strings and many-body decays of resonances.

A new mechanism for the $p\overrightarrow{p}\mathrm{pp}{\pi }^0$ reaction close to threshold is suggested coming from the isoscalar excitation of the Roper and its decay into $N(\pi \pi {)}_{s-\mathrm{w}\mathrm{a}\mathrm{v}\mathrm{e}},$ with one of the ${\pi }^0$ emitted and the other one reabsorbed on the second nucleon. We show that this new mechanism can lead to important interference with other mechanisms suggested so far.

High spin states in the odd-odd $N=Z$ nucleus ${}^{46}\mathrm{V}$ have been identified. At low spin, the $T=1\mathrm{}$ isobaric analog states of ${}^{46}\mathrm{Ti}$ are established up to $I^{\pi }{=6\mathrm{}}^{+}.$ Other high spin states, including the band terminating state, are tentatively assigned to the same $T=1\mathrm{}$ band. The $T=0\mathrm{}$ band built on the low-lying $3^{+}$ isomer is observed up to the ${1f}_{7/2}$-shell termination at $I^{\pi }{=15\mathrm{}}^{+}.$ Both signatures of a negative parity $T=0\mathrm{}$ band are observed up to the terminating states at $I^{\pi }{=16\mathrm{}}^{-}$ and $I^{\pi }{=17\mathrm{}}^{-},$ respectively. The structure of this band is interpreted as a particle-hole excitation from the ${1d}_{3/2}$ shell. Spherical shell model calculations are found to be in excellent agreement with the experimental results.

The $\gamma$ radiation and neutrons emitted following the $\beta$ decays of ${}^{24}\mathrm{O},$ ${}^{25–27}\mathrm{F},$ and ${}^{28-30}\mathrm{Ne}$ have been measured. The nuclides were produced in the quasifragmentation of a 2.8 GeV ${}^{36}\mathrm{S}$ beam, separated in-flight and identified through time-of-flight and energy-loss measurements. The ions were stopped in a silicon detector telescope, which was used to detect the $\beta$ particles emitted in their subsequent radioactive decay. The coincident $\gamma$ rays were measured using four large volume germanium detectors mounted close to the implantation point and the neutrons were detected using 42 ${}^3\mathrm{He}$ proportional counters. The measured $\gamma$-ray energy spectra are compared with shell model calculations and, where available, the level energies deduced from multinucleon transfer reactions.

Experiment E910 has measured slow protons and deuterons from collisions of 18 $\mathrm{GeV}/c$ protons with Be, Cu, and Au targets at the BNL AGS. These correspond to the “grey tracks” first observed in emulsion experiments. We report on their momentum and angular distributions and investigate their use in measuring the centrality of a collision, as defined by the mean number of projectile-nucleon interactions. The relation between the measured $N_{\mathrm{grey}}$ and the mean number of interactions $\overline{\nu }{(N}_{\mathrm{grey}})$ is studied using several simple models, one newly proposed, as well as the RQMD event generator. RQMD is shown to reproduce the $N_{\mathrm{grey}}$ distribution, and exhibits a dependence of $N_{\mathrm{grey}}$ on centrality that is similar to the behavior of the simple models. We find a strong linear dependence of $\overline{N_{\mathrm{grey}}}$ on $\nu$, with a constant of proportionality that varies with target. For the Au target, we report a relative systematic error for extracting $\overline{\nu }{(N}_{\mathrm{grey}})$ that lies between 10 and 20 % over all $N_{\mathrm{grey}}.$

First order Bose condensation in asymmetric nuclear matter and in neutron stars is studied, with particular reference to kaon condensation. We demonstrate explicitly why the Maxwell construction fails to assure equilibrium in multicomponent substances. Gibbs conditions and conservation laws require that for phase equilibrium, the charge density must have opposite sign in the two phases of isospin asymmetric nuclear matter. The mixed phase will therefore form a Coulomb lattice with the rare phase occupying lattice sites in the dominant phase. Moreover, the kaon condensed phase differs from the normal phase, not by the mere presence of kaons in the first, but also by a difference in the nucleon effective masses. The mixed phase region, which occupies a large radial extent amounting to some kilometers in our model neutron stars, is thus highly heterogeneous. It should be particularly interesting in connection with the pulsar glitch phenomenon as well as transport properties.

We propose a discovery experiment for production and identification of isotopes of unobserved elements up to element 119. We predict decay properties of nuclear systems that might be obtained in this experiment and discuss posibilities of identification of new elements on the basis of the calculated properties.

Recent calculations using random two-body interactions showed a preponderance of $J^P{=0\mathrm{}}^{+}$ ground states, despite the fact that there is no strong pairing character in the force. We carry out an analysis of a system of identical particles occupying orbits with $j=1/2,$ 3/2, and 5/2 and discuss some general features of the spectra derived from random two-body interactions. We show that for random two-body interactions that are not time-reversal invariant the dominance of $0^{+}$ states in this case is more pronounced, indicating that time-reversal invariance cannot be the origin of the $0^{+}$ dominance.

High energy solar neutrinos can come from the hep reaction, ${}^3\mathrm{He}(p,\nu e^{+}{)}^4\mathrm{He},$ with a large end point energy of 18.8 MeV. Understanding the hep reaction may be important for interpreting solar neutrino spectra. We calculate the contribution of the axial-charge transition ${}^3{\overrightarrow{P_0}}^1{S}_0$ to the hep thermonuclear S factor using a one-body reaction model involving a nucleon moving in optical potentials. Our result is comparable to or larger than previous calculations of the s-wave Gamow-Teller contribution. This indicates that the hep reaction may have p-wave strength leading to an enhancement of the S factor.

The random phase approximation (RPA), the renormalized RPA (RRPA), and the self-consistent RPA (SCRPA) methods are applied to calculate the wave functions of the ground and excited states of an exactly solvable model. The approximated wave functions are expanded in the basis of the exact solutions. It is found that, when the RPA collapses, the RPA wave functions are orthogonal to the exact solutions while the RRPA and SCRPA ones have small but finite overlaps with the exact results. In spite of the apparently good agreement between the results of the RRPA, the SCRPA, and the exact solution, for the energy of the first excited state beyond the point of collapse, it is found that these approximations do not correctly describe the exact wave functions.

Lifetime measurements on the high-spin rotational bands in ${}^{133}\mathrm{Nd}$ have been carried out by the Doppler-shift attenuation method using the GASP array. The ${}^{133}\mathrm{Nd}$ nuclei were populated in the ${}^{104}\mathrm{Pd}{(}^{32}\mathrm{S},2pn)$ reaction at a bombarding energy of 135 MeV. The Doppler-broadened line shapes were analyzed for Au-backed and Gd-backed targets. Values of $Q_t=4.7\mathrm{}\left(5\right)\mathrm{}$, 5.6(5), and $7.4\left(4\right)\mathrm{}\hspace{0.5em}e\mathrm{b}\mathrm{}$ have been determined for the mean transitional quadrupole moments of the ground-state band, the negative-parity band involving the neutron $h_{9/2}{/f}_{7/2}$ intruder orbitals, and the band built on the neutron $\left[660\right]{1/2}^{+}$ intruder orbital, respectively. The presently determined quadrupole moments are compared with those of the low-spin members of the bands derived elsewhere from recoil distance method measurements. The observed polarizing effects of the neutron intruder orbitals are compared with cranked shell model predictions.

The ${}^{14}\mathrm{Be}$ two-neutron halo nucleus is described within a two-neutron pairing model. In order to reproduce the measured two-neutron separation energy in ${}^{14}\mathrm{Be}$ and the $d_{5/2}$ resonance in ${}^{13}\mathrm{Be}$ at the measured energy of 2 MeV, one has to assume in ${}^{13}\mathrm{Be}$ the inversion of ${1p}_{1/2}$ and ${2s}_{1/2}$ shells as in ${}^{11}\mathrm{Be}$ and ${}^{10}\mathrm{Li}$. We thus predict the ground state of ${}^{13}\mathrm{Be}$ to be a ${1/2}^{-}$ state unbound by about 0.3 MeV, instead of a ${1/2}^{+}$ state as usually accepted.

Extending the earlier work of Bateman et al., we have measured the energy-integrated yield of ${}^{26}{\mathrm{Al}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ from the ${}^{16}\mathrm{O}{(}^{16}\mathrm{O}{,x)}^{26}{\mathrm{Al}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ and ${}^{16}\mathrm{O}{(}^{14}\mathrm{N}{,x)}^{26}{\mathrm{Al}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ reactions. We find that although the yield from the ${}^{16}\mathrm{O}{(}^{16}\mathrm{O}{,x)}^{26}{\mathrm{Al}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ reaction is several times larger than from the ${}^{12}\mathrm{C}{(}^{16}\mathrm{O}{,x)}^{26}{\mathrm{Al}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ reaction, the abundance of fossil ${}^{26}{\mathrm{Al}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ observed in carbonaceous chondrite meteorites could be produced by oxygen-rich cosmic rays via the ${}^{16}\mathrm{O}{(}^{16}\mathrm{O}{,x)}^{26}{\mathrm{Al}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ reaction only under the improbable scenario that more than 40% of the solar system oxygen was injected into the protosolar nebula as cosmic rays.

We start from a Lagrangian describing scalar “nucleons” and mesons which interact through a simple vertex. Okubo’s method of unitary transformation is used to describe a single nucleon dressed by its meson cloud. We find an expression for the physical mass of the nucleon being correct up to second order in the coupling constant. It is then verified that this result is the same as the corresponding expression found by Feynman techniques. Finally we also express the three boost operators in terms of the physical nucleon mass. Doing so we find expressions for all the ten generators of Poincaré transformations for the system of one single dressed nucleon.

The strength distribution of low-lying dipole excitations in the medium-weight vibrational nucleus ${}^{112}\mathrm{Cd}$ was investigated by means of nuclear resonance fluorescence experiments (NRF) performed at the bremsstrahlung beam of the Stuttgart Dynamitron accelerator (end-point energy 4.1 MeV). Detailed information on excitation energies, spins, decay widths, and transition probabilities of about 20 new spin-1 states in ${}^{112}\mathrm{Cd}$ has been obtained. In comparison with comprehensive spectroscopic information available for ${}^{112}\mathrm{Cd}$ conclusions on the parities of the lowest states can be made. A strongly excited $J^{\pi }{=1\mathrm{}}^{-}$ state is interpreted as the $1^{-}$ member of the quadrupole-octupole coupled quintuplet. The observed transition intensities are described in the framework of the interacting boson model and compared with those obtained from recent nuclear resonance fluorescence experiments on the neighboring Cd isotopes ${}^{113,114}\mathrm{Cd}.$

Gamma ray spectra in the range of $\sim 8–35\mathrm{MeV}$ have been measured at $45°,$ $90°,$ and $135°$ in the reaction ${p+}^{197}\mathrm{Au}$ at $E_p=27\mathrm{}\mathrm{MeV}.$ The statistical and the nucleon-nucleon bremsstrahlung models fail to describe the data. The direct-semidirect capture model works well for $E_{\gamma }>20\mathrm{}\mathrm{MeV}.$ The possibility of extracting information on the single particle strength distribution in the final nucleus has been illustrated.