We have identified three modes of radioactive decay of ${}_{}{}^{234}{}_{}{}^{}\mathrm{U}$ by barrier penetration (in addition to alpha decay): emission of a Ne ion, emission of a Mg ion, and spontaneous fission. Lifetimes are (3.7${\pm }_{0.9}^{1.2}$) × ${10}^{17}$, (1.1${\pm }_{0.6}^{1.3}$) × ${10}^{18}$, and (1.9±0.1) × ${10}^{16}$ yr, respectively. This is the first example of a nuclide with four hadronic decay modes.

Absolute gamma intensities have been measured for the strong transitions in the decay chain ${}_{}{}^{98}{}_{}{}^{}\mathrm{Rb}$→ ${}_{}{}^{98}{}_{}{}^{}\mathrm{Sr}$→ ${}_{}{}^{98}{}_{}{}^{}\mathrm{Y}$→ ${}_{}{}^{98}{}_{}{}^{}\mathrm{Zr}$ and ${}_{}{}^{98}{}_{}{}^{}\mathrm{Nb}$→ ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}$ and found approximately four times higher than those currently adopted. As a consequence, several contradictions in this critical chain of nuclei are resolved. Shape coexistance is established in ${}_{}{}^{98}{}_{}{}^{}\mathrm{Y}$ with a $J^{\pi }=1^{-}$ "spherical" ground state and with a previously reported deformed band with band head at 495.7 keV.

Our previous model is used and improved to estimate branching ratios for $B=0\mathrm{}$ (N¯N) and $B=1\mathrm{}$ (N¯NN) annihilations. Particular emphasis is put on the two-body exit channels. It is pointed out that relative values of two-body exit channel branching ratios in $B=1\mathrm{}$ annihilations are largely model independent. Nuclear effects in p¯-nucleus annihilation at rest are estimated.

Motivated by the close similarity between a sum rule originally derived by Cabibbo and Radicati and a simplified version based on nonrelativistic nuclear physics in the long-wavelength limit, we have investigated the effect of retardation corrections. An account of the contributions due to higher multipolarities is presented, together with a physical interpretation of the results.

Employing the W-matrix representation of the partial-wave T matrix introduced by Bartnik, Haberzettl, and Sandhas, we show for the example of the Malfliet-Tjon potentials I and III that the single-term separable part of the W-matrix representation, when used as input in three-nucleon neutron-deuteron scattering calculations, is fully capable of reproducing the exact results obtained by Kloet and Tjon. This approximate two-body input not only satisfies the two-body off-shell unitarity relation but, moreover, it also contains a parameter which may be used in optimizing the three-body data. We present numerical evidence that there exists a variational (minimum) principle for the determination of the three-body binding energy which allows one to choose this parameter also in the absence of an exact reference calculation. Our results for neutron-deuteron scattering show that it is precisely this choice of the parameter which provides optimal scattering data. We conclude that the W-matrix approach, despite its simplicity, is a remarkably efficient tool for high-quality three-nucleon calculations.

Differential cross sections for the ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$(p,n${)}^{34}$Cl reaction were measured at $E_{\mathrm{p}=35\mathrm{}}$ MeV. Remarkable differences were observed among the angular distribution shapes for the known $1^{+}$ states in ${}_{}{}^{34}{}_{}{}^{}\mathrm{Cl}$ at 0.441, 0.666, 2.581, and 3.128 MeV. Distorted-wave Born approximation calculations using the recent full sd-shell wave functions of Brown and Wildenthal successfully reproduce such differences, whose origin was traced back to the different contributions of the ΔJ(ΔL,ΔS)=1(0,1) and 1(2,1) transition amplitudes. The $1^{+}$ transitions with dominant 1(0,1) amplitudes required a renormalization factor N of about 0.8, which agrees well with that obtained for the ${\beta }^{+}$ decay of ${}_{}{}^{34}{}_{}{}^{}\mathrm{Ar}$. The $1^{+}$ and $2^{+}$ transitions with dominant 1(2,1) and 2(2,1) amplitudes required N of about 0.5. Similar distorted-wave Born approximation calculations gave a good description of the ΔS=0 and ΔL=0 and 2 transitions without any renormalization.

Off-shell properties of individual partial waves of the nucleon-alpha potential are systematically investigated by nucleon-nucleon-alpha Faddeev calculations. For this purpose, the ground state energies of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^6{}_{}{}^{}\mathrm{He}$ and the observables of the d-α scattering system at $E_{\alpha }$=15 and 24 MeV (lab) are calculated and compared with experiment. From inspection of the nucleon-alpha wave functions, a suitable short range behavior can be proposed.

Excited states of ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ up to an excitation energy of 15 MeV have been studied by high-resolution electron scattering for momentum transfers between 0.8 and 2.6 ${\mathrm{fm}}^{\mathrm{-}1}$. Previous electron-scattering measurements in this excitation region were confined to momentum transfers below 1.1 ${\mathrm{fm}}^{\mathrm{-}1}$ and were of lower resolution. Form factors were measured and reduced transition probabilities determined for most excited states below 9.5 MeV. The present data are interpreted within the framework of weak-coupling models to facilitate a simple description of the observed spectrum. Particular emphasis is placed upon understanding states that are excited strongly by electric quadrupole or octupole transitions. Spins and parities have been assigned for several levels that have very narrow widths and, hence, are not amenable to partial-wave analyses involving the ${}_{}{}^{16}{}_{}{}^{}$O+n and ${}_{}{}^{13}{}_{}{}^{}$C+α reactions. Levels at 5.87 MeV (${(3/2\mathrm{}}^{+}$), 6.86 MeV (${(5/2\mathrm{}}^{+}$), 7.58 MeV (${(7/2\mathrm{}}^{+}$), and 8.47 MeV (${(9/2\mathrm{}}^{+}$) are suggested as candidates for predominantly 5p-4h members of a $K^{\pi }$${=(3/2\mathrm{}}^{+}$ rotational band. A narrow state (Γ≤20 keV) at 12.22±0.02 MeV was observed for the first time and the existence of narrow states at 8.90±0.02 and 14.72±0.02 MeV was confirmed.

The algebraic structure of the two-Skyrmion system is studied by using bosonic quantization of the rotation of the Skyrmion. The adiabatic interbaryonic potential is expressed in terms of boson operators and the large n (number of bosons) behavior is investigated. By identifying n with $N_c$ (number of colors in quantum chromodynamics), 1/n correction terms for realistic n=$N_c$=3 are studied.

A configuration-space calculation is performed in order to determine the resonant states for a given potential problem. For that purpose we use the spline expansion method to express the Schrödinger equation in an associated matrix form. Comparison with known results reveals that the expansion in a spline basis set provides an accurate and convenient numerical calculation of resonance poles and Gamow states. Resonant states are calculated for a square well plus a barrier in l=0 and l=1, where an exact solution is known, as well as for Reid potential in ${}_{}{}^1{}_{}{}^{}\mathrm{S}_0^{}{}_{}{}^{}$ and ${}_{}{}^1{}_{}{}^{}\mathrm{P}_1^{}{}_{}{}^{}$ channels, and the Ali-Bodmer potential in l=0 and l=2 with and without Coulomb interaction.

A previously proposed approximate method for computing Gamow vectors and momenta is applied to construct a separable representation of a local realistic nucleon-nucleon interaction. It is shown that, in spite of the differences between the exact and approximate vectors and momenta, the resulting separable form gives close agreement with the original local potential for phases and the half-off-shell t matrix.

The tensor polarization of the deuteron calculated in the hybrid quark-hadron model and in a resonating group model is compared to hadronic models and the asymptotic quantum chromodynamic result. We conclude that asymptotic quantum chromodynamics will not apply in the 1–2 GeV/c region under discussion, that quark/gluon phenomena are important, but that the tensor polarization is not an unambiguous signal for quark effects.

The angular distribution of deuterons from the ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$(n,d${)}^{89}$Y reaction at $E_{\mathrm{n}=22\mathrm{}}$ MeV has been measured with a spectrometer consisting of three multiwire proportional counters followed by a curved plastic scintillator. Spectra were obtained with an energy resolution full width at half maximum, of about 0.7 MeV and an angle resolution full width at half maximum, of about 4°. Two prominent peaks were observed in the spectra corresponding to transitions to the ground state and to two states at ∼1.6 MeV excitation in ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$. Distorted wave Born approximation analysis of the angular distributions yielded spectroscopic factors of 1.7(5), 1.8(5), and 0.8(4), respectively, for the transitions to the ground state, the 1.51 MeV state, and the 1.75 MeV state. The results are compared with previous measurements and model predictions.

Inelastic scattering exciting the $2^{+}$ and $4^{+}$ members of the $K^{\pi }$${=2\mathrm{}}^{+}$ γ-vibrational band in ${}_{}{}^{152}{}_{}{}^{}$,154Sm, ${}_{}{}^{160}{}_{}{}^{}\mathrm{Gd}$, ${}_{}{}^{164}{}_{}{}^{}\mathrm{Dy}$, ${}_{}{}^{166}{}_{}{}^{}$,168Er, ${}_{}{}^{176}{}_{}{}^{}\mathrm{Yb}$, ${}_{}{}^{182}{}_{}{}^{}$,184W, and ${}_{}{}^{192}{}_{}{}^{}\mathrm{Os}$ has been measured with 65-MeV polarized protons. Coupled-channel analyses have been performed assuming the γ-vibrational model or the asymmetric rotor model. A large hexadecapole ($Y_{42}$) term in the γ motion is necessary in both models in order to reproduce the experimental data. The quadrupole ($Y_{22}$) and hexadecapole ($Y_{42}$) transition strengths to the γ-vibrational band have been extracted systematically from the optical potential parameters and the deformation parameters for the first time. These show a strong mass number dependence, and can be understood qualitatively by a simple geometrical picture together with the quadrupole ($Y_{20}$) and hexadecapole ($Y_{40}$) moments. The experimental $Y_{22}$ and $Y_{42}$ strengths have been compared with a random-phase-approximation calculation. This suggests the importance of the hexadecapole degree of freedom in the γ vibration. A density-dependent Hartree-Fock calculation explains the quadrupole ($Y_{20}$) moments and the trend of the hexadecapole ($Y_{40}$) moments of the deformed optical potentials very well. The effect of the density dependence of the effective interaction is also discussed through the $Y_{20}$ moments and $Y_{22}$ strengths.

The dispersion relation approach is used to extrapolate towards negative energy the average potential felt by neutrons in yttrium, using as input empirical values of the optical-model potential. At positive energy the absolute value of the volume integral of the potential decreases approximately linearly with energy, but it sharply increases with energy in the vicinity of the Fermi energy, i.e., in the domain which corresponds to the valence bound neutron shells. This Fermi-surface anomaly is quite similar to that which has recently been investigated in the case of neutrons in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. It mainly reflects the energy dependence of the potential radius, although the energy dependence of the potential depth also has a characteristic nonmonotonic behavior and plays a significant role. The energy and radial dependence of the effective mass is exhibited.

The level structure of ${}_{}{}^{112}{}_{}{}^{}\mathrm{Cd}$ has been investigated with the reaction ${}_{}{}^{110}{}_{}{}^{}\mathrm{Cd}$(t,p), at $E_{\mathrm{t}=15.0\mathrm{}}$ MeV. Twenty-nine angular distributions have been measured and compared to predictions of distorted-wave Born-approximation calculations to extract L, and hence $J^{\pi }$, values.

Angular distribution of the ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$(e,${\mathrm{p}}_0$) reaction has been measured in the giant resonance energy region at 12 laboratory angles ranging from 30° to 140°. The obtained differential cross sections have been decomposed into E1 and E2 components using a resonance model. The E1 and E2 components of the ${}_{}{}^{89}{}_{}{}^{}(\gamma$,${\mathrm{p}}_0$) cross section were estimated to exhaust 2.9% and 1.7% of the E1 and E2 sums, respectively. The derived excitation functions for E1 and E2 are well explained by a direct-semidirect model. The result confirms the isovector giant quadrupole excitation in ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$.

The role of core polarization and of the quenching of the leading shell model configuration in stretched spin states is investigated in a case study of the $9^{\mathrm{-}}$ state at 3.522 MeV in ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$. With data on five independent observables available, this is the best documented example of a natural parity stretched (yrast) state. The observables are the electron scattering longitudinal and transverse form factors, the proton-scattering cross section and asymmetry, and the proton-stripping cross section on ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$. By introducing a fully microscopic description of the core polarization, it is possible to account quantitatively for all five observables using an effective nucleon-nucleon interaction based on the free t matrix for the proton scattering and the free values for the coupling constants for electron scattering. A short discussion on the $5^{\mathrm{-}}$ $E_x$=9.70 MeV state in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ and the ${12}^{+}$ $E_x$=6.026 MeV state in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ is given. Quenching factors for the leading shell model components are found to be similar in magnitude as for unnatural parity states.

A quantal method is presented to investigate the spatial development of inelastic scattering cross sections in heavy ion reactions. Application is made to the case of 1120 MeV ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$${+}^{238}$U($0^{+}$,$2^{+}$,...,${40}^{+}$).

The level structures of the doubly-odd nuclei ${}_{}{}^{136}{}_{}{}^{}\mathrm{Pm}$ and ${}_{}{}^{134}{}_{}{}^{}\mathrm{Pr}$ have been studied to high spin following the reactions ${}_{}{}^{114}{}_{}{}^{}\mathrm{Cd}$${(}^{27}$Al,5n${)}^{136}$Pm, ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$${(}^{24}$Mg,p3n${)}^{136}$Pm, and ${}_{}{}^{114}{}_{}{}^{}\mathrm{Cd}$${(}^{27}$Al,α3n${)}^{134}$Pr. The two nuclei show very similar collective features. In both nuclei a rotational band built on the π$h_{11/2}$⊗ν$h_{11/2}$ configuration has been observed. This band shows a constant signature splitting of ∼50 keV with no backbend in both cases. In addition, a sideband built on the π${\left[413\right](5/2\mathrm{}}^{+}$⊗ν$h_{11/2}$ configuration has been observed in ${}_{}{}^{136}{}_{}{}^{}\mathrm{Pm}$. This band becomes yrast at high spins and shows a gain in alignment of ∼8ħ at a frequency of ħω∼0.28 MeV due to the decoupling of a pair of $h_{11/2}$ protons. In ${}_{}{}^{134}{}_{}{}^{}\mathrm{Pr}$ the sideband was only observed above the band crossing. Experimental ratios of reduced transition probabilities, B(M1)/B(E2), have been extracted from transitions within the bands and compared to theoretical values obtained from a semiclassical model.