In this article we examine to what extent traces of α clustering can be found in mean-field ground states of $n\alpha$ nuclei from ${}^8\mathrm{Be}$ through ${}^{36}\mathrm{Ar}$ as well as in some superdeformed states in ${}^{32}\mathrm{S}$, ${}^{36}\mathrm{Ar}$, and ${}^{40}\mathrm{Ca}$. For this purpose we calculate the overlap of the mean-field Slater determinant with one containing pure Gaussians and perfect spin and isospin symmetry, optimizing the overlap by varying the α-particle positions and radii. In some cases a coherent sum over different configurations is also employed. We find quite large overlaps for some of the lighter systems that diminish for nuclei above ${}^{20}\mathrm{Ne}$ but again strong clustering in ${}^{36}\mathrm{Ar}$.

The extended coherent state model is further extended to describe two dipole bands of different parities. The formalism provides a consistent description of eight rotational bands. A unified description for spherical, transitional, and deformed nuclei is possible. Projecting out the angular momentum and parity from a sole state, the $K^{\pi }=1^{+}$ band acquires a magnetic character, whereas the electric properties prevail for the other band. Signatures for a static octupole deformation in some states of the dipole bands are pointed out. Some properties that distinguish between the dipole band states and states of the same parity but belonging to other bands are mentioned. Interesting features concerning the decay properties of the two bands are found. Numerical applications are made for ${}^{158}\mathrm{Gd}$, ${}^{172}\mathrm{Yb}$, ${}^{228,232}\mathrm{Th}$, ${}^{226}\mathrm{Ra}$, ${}^{238}\mathrm{U}$, and ${}^{238}\mathrm{Pu}$, and the results are compared with the available data.

Using the relativistic impulse approximation with the Love-Franey $\mathit{NN}$ scattering amplitude developed by Murdock and Horowitz, we investigate the low-energy ($100⩽E_{\mathrm{kin}}⩽400$ MeV) behavior of the nucleon Dirac optical potential, the Schrödinger-equivalent potential, and the nuclear symmetry potential in isospin asymmetric nuclear matter. We find that the nuclear symmetry potential at fixed baryon density decreases with increasing nucleon energy. In particular, the nuclear symmetry potential at saturation density changes from positive to negative values at nucleon kinetic energy of about 200 MeV. Furthermore, the obtained energy and density dependence of the nuclear symmetry potential is consistent with those of the isospin- and momentum-dependent MDI interaction with $x=0$, which has been found to describe reasonably well both the isospin diffusion data from heavy-ion collisions and the empirical neutron-skin thickness of ${}^{208}\mathrm{Pb}$.

A tagged medium-energy neutron beam was used in a precise measurement of the absolute differential cross section for $\mathit{np}$ backscattering. The results resolve significant discrepancies within the $\mathit{np}$ database concerning the angular dependence in this regime. The experiment has determined the absolute normalization with $\pm 1.5\%$ uncertainty, suitable to verify constraints of supposedly comparable precision that arise from the rest of the database in partial wave analyses. The analysis procedures, especially those associated with the evaluation of systematic errors in the experiment, are described in detail so that systematic uncertainties may be included in a reasonable way in subsequent partial wave analysis fits incorporating the present results.

The high-spin parts of shears bands observed in ${}^{198,199}\mathrm{Pb}$ are described by coupling several valence particles to a deformed rotor core. To give the model enough freedom so that both the proton and the neutron spin vectors can find their preferred direction, the use of five to six valence particles and holes is found to be necessary. Effective parameters characterizing the rotor are deduced from the cranking model. The method is described and results are presented concerning transition probabilities and energies in the high-spin regime for several rotational bands in ${}^{199}\mathrm{Pb}$. The possible termination of the rotational bands is also discussed.

The giant resonance region from 9 MeV $<E_x<55$ MeV in ${}^{46}\mathrm{Ti}$ and ${}^{48}\mathrm{Ti}$ has been studied with inelastic scattering of 240 MeV $\alpha$ particles at small angles including $0^{°}$. Isoscalar monopole strength in ${}^{46}\mathrm{Ti}$ (${}^{48}\mathrm{Ti}$) was found corresponding to have $71+15/-12\%$ ($96+14/-12\%$) of the $E0$ energy weighted sum rule (EWSR) with a centroid of $18.66+0.65/-0.25\%$ MeV ($18.80+0.45/-0.18\%$ MeV), respectively. In ${}^{46}\mathrm{Ti}$ (${}^{48}\mathrm{Ti}$), $46\pm 12\%$ ($56\pm 12\%$) of the $E1$, and $60\pm 11\%$ ($87\pm 11\%$) of the $E2$ EWSR were identified.

The nature of $0^{+}$ excitations, especially in transitional and deformed nuclei, has attracted new attention. Following a recent experiment studying ${}^{158}\mathrm{Gd}$, we investigated a large group of nuclei in the rare-earth region with the $(p,t)$ pickup reaction using the Q3D magnetic spectrograph at the University of Munich MP tandem accelerator laboratory. Outgoing tritons were recorded at various lab angles, and their angular distributions are compared to those calculated using the distorted-wave Born approximation. Using the unique shape of the $L=0$ angular distribution, more than double the number of $0^{+}$ states than were previously known are identified. The distribution of 0${}^{+}$ energies and cross sections is discussed in terms of collective and noncollective degrees of freedom, and the density of low-lying $0^{+}$ states is discussed as a corroboration of a characteristic feature of phase transition regions. The degree of level mixing, as extracted from Brody distribution fits to the energy spacings of adjacent $0^{+}$ levels, is also explored.

New isotope, ${}^{264}\mathrm{Sg}$, was identified using the ${}^{238}\mathrm{U}$(${}^{30}\mathrm{Si}$, x$n$)${}^{268-x}\mathrm{Sg}$ reaction and excitation functions for ${}^{262-264}\mathrm{Sg}$ were measured. ${}^{264}\mathrm{Sg}$ decays by spontaneous fission with a half-life of ${37}_{-11}^{+27}$ ms. The spontaneous fission branch for 0.9-s ${}^{263}\mathrm{Sg}$ was measured for the first time and found to be (13±8)%. ${}^{262}\mathrm{Sg}$ decays by spontaneous fission with a ${15}_{-3}^{+5}$ ms half-life. Spontaneous fission partial half-life systematics are evaluated for even-even Sg isotopes from ${}^{258}\mathrm{Sg}$ through ${}^{266}\mathrm{Sg}$, spanning the transition region between the $N=152,Z=100$ and $N=162,Z=108$ deformed shells.

Isotopic production cross sections and momentum distributions of 602 residual nuclei produced in the collision of ${}^{238}\mathrm{U}$($1A$ GeV) with deuterium have been measured. These data are relevant for a better understanding of spallation reactions for use as neutron sources for accelerator-driven systems or to produce radioactive nuclear beams. Access to primary residue production makes it possible to study the main reaction mechanisms involved: intranuclear cascade, particle evaporation, and fission. The characteristics of the reaction investigated and the high fissility of the ${}^{238}\mathrm{U}$ and the dinucleon projectile system are discussed and compared with other available experimental data.

We present results from a comprehensive partial-wave analysis of ${\pi }^{\pm }p$ elastic scattering and charge-exchange data, covering the region from threshold to 2.6 GeV in the lab pion kinetic energy, employing a coupled-channel formalism to simultaneously fit ${\pi }^{-}p\to \eta n$ data to 0.8 GeV. Our main result, solution SP06, utilizes a complete set of forward and fixed-$t$ dispersion relation constraints applied to the $\pi N$ elastic amplitude. The results of these analyses are compared with previous solutions in terms of their resonance spectra and preferred values for couplings and low-energy parameters.

Within the statistical multifragmentation model we study modifications of the surface and symmetry energy of primary fragments in the freeze-out volume. The ALADIN experimental data on multifragmentation obtained in reactions induced by high-energy projectiles with different neutron richness are analyzed. We have extracted the isospin dependence of the surface energy coefficient at different degrees of fragmentation. We conclude that the surface energy of hot fragments produced in multifragmentation reactions differs from the values extracted for isolated nuclei at low excitation. At high fragment multiplicity, it becomes nearly independent of the neutron content of the fragments.

We have applied the Giessen BUU (GiBUU) transport model to the description of the double-charge exchange (DCX) reaction of pions with different nuclear targets at incident kinetic energies of 120–180 MeV. The DCX process is highly sensitive to details of the interactions of pions with the nuclear medium and, therefore, represents a major benchmark for any model of pion scattering off nuclei at low and intermediate energies. The impact of surface effects, such as the neutron skins of heavy nuclei, is investigated. The dependence of the total cross section on the nuclear mass number is also discussed. We achieve a good quantitative agreement with the extensive data set obtained at LAMPF. Furthermore, we compare the solutions of the transport equations obtained in the test-particle ansatz using two different schemes: the full and the parallel ensemble methods.

We discuss theoretically the possibility of observing the bound states of the η and ${\eta }^{\text{'}}(958)$ mesons in nuclei. We apply the NJL model to study the η and ${\eta }^{\text{'}}$ meson properties at finite density and calculate the formation cross sections of the η and ${\eta }^{\text{'}}$ bound states with the Green function method for ($\gamma ,p$) reaction. We also discuss the experimental feasibility at photon facilities like SPring-8. The contributions due to the ω meson production are also included to obtain the realistic ($\gamma ,p$) spectra. We conclude that we can expect to observe resonance peaks in ($\gamma ,p$) spectra for the formation of meson bound states and we can deduce new information on η and ${\eta }^{\text{'}}$ properties at finite density. These observations are believed to be essential to know the possible mass shift of ${\eta }^{\text{'}}$ and deduce new information on the effective restoration of the $U_A(1)$ anomaly in the nuclear medium.

The helicity dependence of the $\gamma p\to n{\pi }^{+}$ reaction has been measured for the first time in the photon energy range from 450 to 790 MeV. The experiment, performed at the Mainz Microtron (MAMI), used a $4\pi$-detector system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. Although these polarized data are mainly sensitive to mechanisms involving the $D_{13}(1520)$ resonance, a cusp structure at the η production threshold can be clearly observed. These data are significantly different from the predictions of the existing multipole analyses and are used to determine the helicity amplitudes of the $D_{13}(1520)$ and $S_{11}(1535)$ resonances with improved accuracy.

Radium was radiochemically separated from natural thorium. Thin ${}^{228}\mathrm{Ra}$$\stackrel{{\beta }^{-}}{\to }$${}^{228}\mathrm{Ac}$ sources were prepared and exposed to mica fission track detectors, and measured by an HPGe $\gamma$-ray detector. The $\beta$-delayed fission events of ${}^{228}\mathrm{Ac}$ were observed and its β-delayed fission probability was found to be ($5\pm 2)\times {10}^{-12}$.

We determine the saturation properties of nuclear matter within the Brueckner-Hartree-Fock approach based on a large set of modern nucleon-nucleon potentials and confirm the validity of the Coester band. The improvement of the saturation point when including nuclear three-body forces is pointed out and comparison with the Dirac-Brueckner-Hartree-Fock results is made.

Deformations of hot composite ${}^{32}\mathrm{S}$${}^{*}$ formed in the reaction ${}^{20}\mathrm{Ne}$(∼7–10 MeV/nucleon) + ${}^{12}\mathrm{C}$ have been estimated from the respective inclusive α-particle evaporation spectra. The estimated deformations for ${}^{32}\mathrm{S}$${}^{*}$ have been found to be much larger than the “normal” deformations of hot, rotating composites at similar excitations. This further confirms the formation of a highly deformed long-lived configuration of ${}^{20}\mathrm{Ne}+{}^{12}\mathrm{C}$ at high excitations (∼70–100 MeV)—which was recently indicated from analysis of complex fragment emission data for the same system. Exclusive α-particle evaporation spectra from the decay of hot composite ${}^{32}\mathrm{S}$${}^{*}$ also show similar behavior.

We present new cross section data for the complete fusion of the weakly bound systems ${}^{7,9}\mathrm{Be}$ and ${}^7\mathrm{Li}$ on ${}^{238}\mathrm{U}$ at energies around the Coulomb barrier. In the same measurement, yields for direct processes and incomplete fusion are detected. For all systems, a suppression of the complete fusion cross section around and above the barrier is observed. At energies below the barrier, the fusion of the ${}^7\mathrm{Be}+{}^{238}\mathrm{U}$ system shows no enhancement with respect to simple model predictions.

The capture-fission cross section was measured for the reaction of ${}^{38}\mathrm{S}$ with ${}^{208}\mathrm{Pb}$ for center-of-mass projectile energies $E_{\mathrm{cm}}$ of 160–265 MeV. The ${}^{38}\mathrm{S}$ beam was prepared by projectile fragmentation at the NSCL at higher energies and degraded to 4–7 MeV/nucleon. The time of flight (energy) of each interacting beam particle was measured along with the fission fragments. The data were compared to previous measurements of the capture-fission excitation function for the ${}^{32}\mathrm{S}+{}^{208}\mathrm{Pb}$ reaction. The interaction barrier for the ${}^{38}\mathrm{S}$-induced reaction is $16.1\pm 10.1$ MeV lower than the ${}^{32}\mathrm{S}$-induced reaction whereas the reduced excitation functions for the two reactions are similar. A discussion of the systematics of barrier shifts in the fusion of $n$-rich nuclei is given and the implications of this shift for the synthesis of heavy nuclei with radioactive beams are discussed.

Production cross sections for the projectile fragmentation of a 1.05$A$ GeV ${}^{80}\mathrm{Kr}$ beam on a Be target were measured at the projectile fragment separator FRS at GSI. Cross sections were obtained for isotopes of the elements Ge to Kr close to the proton drip line. These data are compared to the results of the empirical parametrization EPAX and to abrasion-ablation calculations. We also compare the results to predictions of intranuclear-cascade calculations. The intranuclear-cascade calculations allow us to also compare well measured one-proton pickup cross sections.