The spherical basis for the P factor is emphasized and its applicability to the transactinide elements is discussed in light of the enhanced stability found in this region.

The nuclide ${}^{69}$Kr with $T_z=-3/2$, $A=4n+1\mathrm{}$ produced in the ${}^{40}\mathrm{Ca}{(}^{32}\mathrm{S},3n)$ reaction has been observed via β-delayed proton emission by using pulsed-beam technique. A single proton group at a laboratory energy of $4.07\pm 0.05$ MeV with half-life of 32±10 ms was observed for the first time, corresponding to decay of the $T=3/2\mathrm{}$ isobaric analog state in ${}^{69}$Br to the ground state of ${}^{68}$Se. Combining this result with a Coulomb displacement energy calculation yields a mass excess for ${}^{69}$Kr of $-32.15\pm 0.30$ MeV. The partial decay scheme of ${}^{69}$Kr is proposed.

The dependence of intermediate-mass-fragment (IMF) element distributions on the multiplicity, $N_{\mathrm{IMF}},$ of detected fragments has been measured for ${}^{84}{\mathrm{K}\mathrm{r}+}^{197}\mathrm{Au}$ collisions at $E/A=35\mathrm{}$, 55, 70, 100, 200, and 400 MeV. The observed dependence can be parametrized as ${P(N}_{\mathrm{IMF}}|Z\left)\propto P\right(Z\left)\mathrm{}\exp \right(-c\cdot N_{\mathrm{IMF}}\cdot Z),$ where $c$ is a beam-energy and excitation-energy dependent parameter. Previous work indicated this parameter is zero in the liquid-gas coexistence region and positive in the gaseous phase. In contrast, we observe both negative and positive values for $c$, revealing the meaning of this parameter to be less straightforward than previously assumed. The magnitude of $c$ appears nonetheless to provide a nontrivial test of multifragmentation models.

We measured the fusion-fission excitation functions for the ${}^{32}$S+${}^{181}$Ta reaction and the ${}^{38}$S+${}^{181}$Ta reaction. (The radioactive ${}^{38}$S beam was produced by projectile fragmentation.) The thresholds were measured to be 137.5$\pm$1.0 and 130.7$\pm$2.0 MeV for the ${}^{32}$S and ${}^{38}$S-induced reactions, respectively. This result agrees with the systematics of fusion excitation functions and may be significant in the synthesis of new heavy nuclei.

An upper limit to the production of ${}^{19}\mathrm{Ne}$ through the ${}^{18}\mathrm{F}(p,\gamma )$ reaction at the recently discovered $s$-wave resonance has been determined. The limit implies that in a hot stellar environment ${(T}_9>0.5)$ this reaction is not a significant gateway from the hot CNO cycle towards the production of heavier elements in stars.

A semiclassical coupled-channels calculation of the elastic breakup of the deuteron is performed in order to demonstrate that strong postacceleration effects are expected to be observable in the longitudinal velocity spectrum of the outgoing proton. The relevance of this phenomenon in elucidating possibly similar effects in the breakup of light halolike radioactive nuclei is stressed.

We use a large-scale $6ħ\Omega$ calculation for ${}^6$Li with microscopically derived two-body interaction to construct the $0ħ\Omega$ $0p$ shell effective Hamiltonian, electric quadrupole, and magnetic dipole operators. While the E2 and M1 $6ħ\Omega$ operators are one-body operators with free nucleon charges, the effective operators are two-body operators with substantially different renormalization for the isoscalar and isovector matrix elements, especially for the E2 operator. We show that these operators can be very well approximated by one-body operators provided that effective proton and neutron charges are used. The obtained effective charges are compatible with those used in phenomenological shell-model studies. The two-body part of the effective operators is estimated.

Predictions are made for the structure of a second 2${}^{+}$ resonance, the soft dipole mode and unnatural parity modes in the ${}^6$He continuum. We use a structure model which describes the system as a three-body $\alpha$+$N$+$N$ cluster structure, giving the experimentally known properties of ${}^6$He and ${}^6$Li, and use the distorted-wave impulse approximation (DWIA) reaction theory appropriate for dilute matter. The presence of both resonant and nonresonant structures in the halo excitation continuum is shown to be manifest in charge-exchange reactions as well as inelastic scattering with single nucleons.

The onset of superfluidity in isospin-asymmetric nuclear matter is investigated within the BCS theory. A neutron-proton superfluid state in the channel ${}^3{S}_1$-${}^3{D}_1$ comes about from the interplay between thermal excitations and separation $\delta \mu$ of the two Fermi surfaces. The superfluid state disappears above the threshold value of the density-asymmetry parameter $\alpha {=(n}_n-n_p)/n\simeq 0.35$. For large enough shift between the two Fermi surfaces $\delta \mu =$$\frac{1}{2}$$\left({\mu }_n-{\mu }_p\right)$ the transition to the normal state becomes a first-order transition and a second gap solution develops. This solution, however, corresponds to a metastable superfluid state which is unstable with respect to the transition to the normal state.

A recent analysis of experimental energy systematics suggests that all collective nuclei fall into one of three classes — seniority, anharmonic vibrational, or rotational — with sharp phase transitions between them. We investigate the transition from the seniority to the anharmonic vibrator regime within a shell model framework involving a single large $j$ orbit. The calculations qualitatively reproduce the observed transitional behavior, both for U(5)-like and O(6)-like nuclei. They also confirm the preeminent role played by the neutron-proton interaction in producing the phase transition.

High-spin states in the odd-odd nucleus ${}^{76}$Br were populated with two different reactions: ${}^{63}$Cu${(}^{16}$O,$n2p)$ and ${}^{63}$Cu${(}^{19}$F,$\alpha pn)$. The Pitt multidetector array was used to collect $\gamma$-$\gamma$ coincidence data. The level scheme has been extended considerably. The features of the level scheme, particularly the signature inversions in the yrast band, are compared to the results of cranked Woods-Saxon shell-model calculations with self-consistent pairing.

The nuclear structure of ${}^{101}$Tc was studied using the ${}^{100}$Mo${(}^3$He,$\mathrm{pn}\gamma )$ reaction, which has populated most states in the nucleus below 2 MeV excitation energy. The proton exit channel was isolated from competing reaction channels by operating $\gamma$-ray detectors in coincidence with a large-solid-angle proton detector. The experiments included $\gamma$-ray excitation functions, $\gamma$-ray angular distributions, and $\gamma$-$\gamma$ coincidences. The results were interpreted using a particle-rotor model.

The level density of ${}^{29}$Si has been studied over an excitation energy range of 3 to 22 MeV. Three techniques were used to derive level density values from experimental data. In the region of resolved levels, results were obtained from level counting while neutron resonance data were used in the region of slightly overlapping levels near the neutron binding energy. At the highest excitation energies, characterized by strongly overlapping levels, Ericson theory was employed to deduce level densities by examining energy-dependent fluctuations in cross sections. Three reactions yielding the same compound nucleus, ${}^{29}$Si, were investigated. Partial cross sections from ${}^{28}$Si($n,p$), ${}^{28}$Si($n$,α), and ${}^{27}$Al($d,n$)${}^{28}$Si reactions were measured with good experimental resolution and statistical accuracy. From these cross sections, level densities were extracted using the two independent methods proposed by Ericson. Reasonable agreement was found among level densities derived from the two Ericson methods. Values obtained are also fairly consistent with those of various predictions and theoretical models.

${}^{186}$Ir has been restudied through the ${}^{180}$Hf${(}^{11}$B,5$n)$ reaction at 65 MeV using in-beam $\gamma$-ray and conversion-electron spectroscopy. The unfavored component of the doubly decoupled band was established and shown to be consistent with a description in terms of the $\pi h_{9/2}\otimes \nu [\widetilde{411}1/2,3/2]$ structure, i.e., the coupling of an aligned proton and a neutron pseudospin doublet.

Four new superdeformed bands have been observed with the Gammasphere array and have been assigned to the ${}^{195}$Hg nucleus. Two of the bands are interpreted as signature partners most likely based on $N_{\mathrm{osc}}$=6 neutron quasiparticles coupled to a superdeformed core, while the other two appear to be based on a $j_{15/2}$ intruder orbital. These four bands do not exhibit a simple, “identical bands” relationship to other superdeformed bands in this mass region.

High spin states in ${}^{113}$In have been established up to 6.2 MeV in excitation energy and to a tentative spin of (43/2${}^{-})$ through the reaction ${}^{110}$Pd${(}^7$Li, ${4n)}^{113}$In at a beam energy of 40 MeV. In-beam measurements involved $\gamma$-$\gamma$ coincidences, angular distribution of emitted gamma rays, and directional correlation of oriented states. $M$1 bands consisting of $\Delta I=1\mathrm{}$ dipole transitions have been observed. Possible quasiparticle configurations suggest that these bands are similar to the shears bands observed in Pb nuclei. Two intruder bands based on the $\pi h_{11/2}$ orbital and $\pi g_{7/2}$ orbital have been observed. Results of the total Routhian surface and cranked shell model calculations are compared with the experimental data. Alignment features of the intruder bands in the $N=62\mathrm{}$ and 64 isotones are discussed.

An effective interaction for relativistic Hartree-Fock (HF) calculations of nuclear structure is constructed. It includes a nonlinear functional of the most simple general form taking into account interactions and self-interactions of isoscalar meson fields. The parameters are determined to reproduce Dirac-Brueckner HF nuclear matter results obtained from different types of one-boson-exchange potential (OBEP) fitting NN scattering data. The effective interaction is used then to calculate ground-state properties of finite nuclei. Results for some specific OBEP’s (BM-B version) are in reasonable agreement with experiment. The symmetry energy coefficient, in particular, is well reproduced. It is found that the ${\mathrm{\sigma }}^2$${\mathrm{\omega }}^2$ and ${\mathrm{\omega }}^4$ components of the effective interaction play an important role.

A total of 34 experimental levels of ${}^{210}$Bi have been fitted with a generalized intermediate coupling model involving a $n$-$p$ interaction with a Gaussian radial dependence with and without coupling to an octupole phonon. ${\chi }^2$ values are somewhat lower with the octupole parameter. Comparison of ${\chi }^2$ values with those obtained by fitting the same 34 experimental levels using the delta force radial dependence indicate the Gaussian radial dependence is 8–10 times lower. The $n$-$p$ interaction parameters are then used to calculate other ${}^{210}$Bi levels.

Complete diagonalizations in the $\mathrm{pf}$ major shell lead to very good agreement with the experimental data (level schemes, transitions rates, and static moments) for the $A=47\mathrm{}$ and $A=49\mathrm{}$ isotopes of Ca, Sc, Ti, V, Cr, and Mn. Gamow-Teller and $M1\mathrm{}$ strength functions are calculated. The necessary monopole modifications to the realistic interactions are shown to be critically tested by the spectroscopic factors for one particle transfer from ${}^{48}$Ca, reproduced in detail by the calculations. The collective behavior of ${}^{47}$Ti, and of the mirror pairs ${}^{47}$V-${}^{47}$Cr and ${}^{49}$Cr-${}^{49}$Mn is found to follow at low spins the particle plus rotor model. It is then analyzed in terms of the approximate quasi-SU(3) symmetry, for which some new results are given.

The first spin-transfer experiment performed for the $\pi d\to \to p\to p$ reaction is described. Three spin-transfer parameters for this $\pi$-absorption process were determined, $K_{\mathrm{LS}}^a$, $K_{\mathrm{SS}}^a$, and $K_{\mathrm{NN}}^a$, which correspond to the π-production parameters, $K_{\mathrm{SL}}^p$, $K_{\mathrm{SS}}^p$, and $K_{\mathrm{NN}}^p$, of the time-reversed $p\to p\to d\to \pi$ process. Each observable was measured at a single angle for a number of energies spanning the $\Delta$ resonance of this system. The results are compared with the predictions of published partial wave amplitude fits which are primarily based on existing data for the time-reversed $\mathrm{pp}\to d\pi$ reaction, and also with the predictions of two current theories. The failure of these theories to describe the fundamental features of the data clearly demonstrates the need for further theoretical work in this area.