We studied in a microscopic multiphonon approach the proton-neutron symmetry and phonon structure of some low-lying states recently discovered in ${}^{92}\mathrm{Zr}$. We confirm the breaking of $F$-spin symmetry, but argue that the breaking mechanism is more complex than the one suggested in the original shell model analysis of the data. We found other new intriguing features of the spectrum, such as a pronounced multiphonon fragmentation of the states and a tentative evidence of a three-phonon mixed-symmetry state.

The coupling of single-particle motion and of vibrations in ${}_4{}^{11}\mathrm{Be}$ produces dressed neutrons which spend only a fraction of the time in pure single-particle states, and which weighing differently from the bare neutrons lead to parity inversion. The interaction of the two least bound neutrons in the ground state of ${}_4{}^{12}\mathrm{Be}$ mediated by the $v_{14}$ Argonne nucleon-nucleon potential and by the exchange of surface vibrations of the core ${}^{10}\mathrm{Be}$ gives rise to a strongly correlated state, where the two valence neutrons are distributed over $s^2,p^2$, and $d^2$ configurations, resulting in the breaking of the $N=8$ shell closure.

The x-ray cascade from antiprotonic atoms was studied for ${}^{122}\mathrm{Te}$, ${}^{124}\mathrm{Te}$, ${}^{126}\mathrm{Te}$, ${}^{128}\mathrm{Te}$, and ${}^{130}\mathrm{Te}$. Widths and shifts due to the strong interaction were deduced for several levels. The $E2$ nuclear resonance effect was observed in all investigated nuclei. In ${}^{130}\mathrm{Te}$ the $E2$ resonance allowed to determine level widths and shifts of the $LS$-split deeply bound $(n,l)=(6,5)$ state, otherwise unobservable. The measured level widths and shifts, corrected for the $E2$-resonance effect, were used to investigate the nucleon density in the nuclear periphery. The deduced neutron distributions are compared with results of the previously introduced radiochemical method and with Hartree-Fock-Bogoliubov model calculations.

Fully quantal calculations of the total reaction cross sections ${\sigma }_{\mathrm{R}}$ and interaction cross sections ${\sigma }_{\mathrm{I}}$, induced by stable and unstable He, Li, C, and O isotopes on ${}^{12}\mathrm{C}$ target at $E_{\text{lab}}\approx 0.8$ and $1\text{GeV}∕\text{nucleon}$ have been performed, for the first time, in the distorted wave impulse approximation (DWIA) using the microscopic complex optical potential and inelastic form factors given by the folding model. Realistic nuclear densities for the projectiles and ${}^{12}\mathrm{C}$ target as well as the complex $t$-matrix parametrization of free nucleon-nucleon interaction by Franey and Love were used as inputs of the folding calculation. Our parameter-free folding + DWIA approach has been shown to give a very good account (within $1–2\%$) of the experimental ${\sigma }_{\mathrm{I}}$ measured at these energies for the stable, strongly bound isotopes. With the antisymmetrization of the dinuclear system properly taken into account, this microscopic approach is shown to be more accurate than the simple optical limit of Glauber model that was widely used to infer the nuclear radii from the measured ${\sigma }_{\mathrm{I}}$. Therefore, the results obtained for the nuclear radii of neutron-rich isotopes under study can be of interest for further nuclear structure studies.

The charge symmetry breaking amplitudes for the recently observed $dd\to \alpha {\pi }^0$ reaction are investigated. Chiral perturbation theory is used to classify and identify the leading-order terms. Specific forms of the related one- and two-body tree-level diagrams are derived. As a first step toward a full calculation, a few tree-level two-body diagrams are evaluated at each considered order, using a simplified set of $d$ and $\alpha$ wave functions and a plane-wave approximation for the initial $dd$ state. The leading-order pion-exchange term is shown to be suppressed in this model because of poor overlap of the initial and final states. The higher-order one-body and short-range (heavy-meson-exchange) amplitudes provide better matching between the initial and final states and therefore contribute significantly and coherently to the cross section. The consequences this might have for a full calculation, with realistic wave functions and a more complete set of amplitudes, are discussed.

We have measured proton and $\alpha$-particle branching ratios of states formed using the ${}^{19}\mathrm{F}\left({}^3\mathrm{He},t\right){}^{19}\mathrm{Ne}^{*}$ reaction at a beam energy of $25\text{MeV}$. These ratios have a large impact on the astrophysical reaction rates of ${}^{15}\mathrm{O}\left(\alpha ,\gamma \right){}^{19}\mathrm{Ne}$, ${}^{18}\mathrm{F}\left(p,\gamma \right){}^{19}\mathrm{Ne}$, and ${}^{18}\mathrm{F}\left(p,\alpha \right){}^{15}\mathrm{O}$, which are of interest in understanding energy generation in x-ray bursts and in interpreting anticipated $\gamma$-ray observations of novae. We detected decay protons and $\alpha$ particles using a silicon detector array in coincidence with tritons measured in the focal plane detector of our Enge split-pole spectrograph. The silicon array consists of five strip detectors of the type used in the Louvain-Edinburgh Detector Array, subtending angles from $130°$ to $165°$ with $\approx 14\%$ lab efficiency. The correlation angular distributions give additional confidence in some prior spin-parity assignments that were based on $\gamma$ branchings. We measure ${\Gamma }_p∕\Gamma =0.387\pm 0.016$ for the $665\text{keV}$ proton resonance, which agrees well with the direct measurement of Bardayan et al.

Experimental nuclear moments of inertia at high spins along the yrast line have been determined for a large number of nuclei. They are found to systematically differ from the rigid-body values. The difference is attributed to shell effects which are well described by a rotating Woods-Saxon potential. The data and quantal calculations are interpreted by means of the semiclassical periodic orbit theory. From this new perspective, features in the moments of inertia as a function of neutron number and spin as well as their relation to the shell energies can be understood. Gross shell effects persist up to the highest angular momenta observed.

By means of the $(p,t)$ reaction we study the excitation spectra of $0^{+}$ states in the deformed nuclei ${}^{228}\mathrm{Th}$, ${}^{230}\mathrm{Th}$, and ${}^{232}\mathrm{U}$, using the Q3D magnetic spectrograph facility at the Munich tandem accelerator. At small reaction angles the $0^{+}$ transfer angular distributions have steeply rising cross sections which allow us to identify these states in otherwise very complicated and dense spectra. For each of these nuclei we resolve typically about ten excited states with safe $0^{+}$ assignments. The studied excitation energies range up to 2.5, 2.7, and $2.3\text{MeV}$, respectively, and the summed transfer strengths add to more than $60\%$ of the ground state strength. As in a recent study of ${}^{158}\mathrm{Gd}$ we compare with interacting boson approximation (IBA) calculations in the $spdf$ boson space. This highly schematic collective model description, including octupole collectivity, but neglecting other relevant degrees of freedom, gives numbers of excited $0^{+}$ states in these actinide nuclei that are rather close to the observed ones.

Fusion-evaporation reactions induced by $110\text{MeV}$ ${}^{11}\mathrm{B}$ and radioactive ${}^{11}\mathrm{C}$ on ${}^{87}\mathrm{Rb}$ targets have been studied by measuring evaporation residue–light particle coincidences. The proton to $\alpha$ particle ratio in each reaction has been derived and compared with predictions from statistical model calculations. These calculations account rather well for the experimental data, when a small empirical adjustment of the emission barrier is performed, in agreement with earlier results. No evidence is found for predicted temperature and isospin modification of the binding energies. The possibility of a further study of isospin and temperature dependent effects in fusion-evaporation reactions with radioactive beams is discussed.

Superfluid properties of the inner crust matter of neutron stars, formed by nuclear clusters immersed in a dilute neutron gas, are analyzed in a self-consistent Hartree-Fock-Bogoliubov approach. The calculations are performed with two pairing forces, fixed so as to obtain in infinite nuclear matter the pairing gaps provided by the Gogny force or by induced interactions. It is shown that the nuclear clusters can either suppress or enhance the pairing correlations inside the inner crust matter, depending on the density of the surrounding neutrons. The profile of the pairing field in the inner crust is rather similar for both pairing forces, but the values of the pairing gaps are drastically reduced for the force which simulates the polarization effects in infinite neutron matter.

The elastic scattering of ${}^{10}\mathrm{Be}$ on ${}^{208}\mathrm{Pb}$ has been measured over a range of energies near the nominal Coulomb barrier. An excitation function for the total reaction cross section is obtained from the elastic-scattering angular distributions and compared with existing fusion data. Comparisons are also made with existing fusion, transfer∕breakup, and elastic data for ${}^9\mathrm{Be}$ incident on ${}^{209}\mathrm{Bi}$. A strong enhancement in the sub-barrier total reaction cross section for ${}^9\mathrm{Be+}{}^{209}\mathrm{Bi}$ relative to ${}^{10}\mathrm{Be+}{}^{208}\mathrm{Pb}$ is demonstrated.

We study the muonic nuclear-polarization corrections, which provide level shifts due to the two-photon exchange process between a bound muon and a nucleus. We choose ${}^{16}\mathrm{O}$ as a nucleus for the demonstration of the amount and the property of the nuclear polarization in the muonic atoms. The nuclear states of ${}^{16}\mathrm{O}$ are constructed in the random-phase approximation including the negative-energy states based on the relativistic mean field model. The spatial components of the transition current have large couplings between positive- and negative-energy states. As a result, the contribution from the negative-energy states of nucleus to the nuclear-polarization correction is found to be significant and also essential to achieve gauge invariance. The nuclear-polarization effect in muonic ${}^{16}\mathrm{O}$ is also calculated using the collective model. We find that the nonrelativistic nuclear model with the effective mass provides similar results as the relativistic one.

The common interpretation of Hanbury-Brown–Twiss (HBT) data measured at top SPS energies lead to apparent source lifetimes of $6–8\text{fm}∕c$ and emission duration of $\approx 2–3\text{fm}∕c$. We investigate a scenario with continuous pion emission from a long-lived $\left(\sim 16\text{fm}∕c\right)$ thermalized source in order to show that it is not excluded by the data. Starting from a description of the source’s space-time expansion based on gross thermodynamical properties of hot matter (which is able to describe a number of experimental observables), we introduce the pion emission function with a contribution from continuous emission during the source’s lifetime and another contribution from the final breakup and proceed by calculating the HBT parameters $R_{\mathit{out}}$ and $R_{\mathit{side}}$. The results are compared with experimental data measured at SPS for $158A\text{GeV}$ central Pb-Pb collisions. We achieve agreement with data, provided that some minor modifications of the fireball evolution scenario are made, and find that the parameter $R_{\mathit{out}}$ is not sensitive to the fireball lifetime, but only to the duration of the final breakup, in spite of the fact that emission takes place throughout the whole lifetime. We explicitly demonstrate that those findings do not alter previous results obtained within this framework.

The data on $m_T$ spectra of $K_S^0$, $K^{+}$, and $K^{-}$ mesons produced in all inelastic $p+p$ and $p+\overline{p}$ interactions in the energy range $\sqrt{s_{NN}}=4.7-1800\text{GeV}$ are compiled and analyzed. The spectra are parametrized by a single exponential function $(dN∕m_{T}d{m}_T)=C{e}^{-m_T∕T}$, and the inverse slope parameter $T$ is the main object of study. The $T$ parameter is found to be similar for $K_s^0$, $K^{+}$, and $K^{-}$ mesons. It increases monotonically with collision energy from $T\approx 130\text{MeV}$ at $\sqrt{s_{NN}}=4.7\text{GeV}$ to $T\approx 220\text{MeV}$ at $\sqrt{s_{NN}}=1800\text{GeV}$. The $T$ parameter measured in $p+p\left(\overline{p}\right)$ interactions is significantly lower than the corresponding parameter obtained for central $\text{Pb}+\text{Pb}$ collisions at all studied energies. Also the shape of the energy dependence of $T$ is different for central $\text{Pb}+\text{Pb}$ collisions and $p+p\left(\overline{p}\right)$ interactions.

Addressing strongly interacting matter in the region of energy density where the hadronic gas phase coexists with the quark-gluon plasma phase, we discuss how thermodynamic consistency can be used to constrain the equation of state for uniform matter. We illustrate the method by constructing a $T_c$-dependent family of thermodynamically consistent equations of state based on simple spline interpolations between the gas and plasma phases.

A study of high-energy $\left(43–68\text{MeV}∕\text{nucleon}\right)$ one-neutron removal reactions on a range of neutron-rich $psd$-shell nuclei $\left(Z=5–9,A=12–25\right)$ has been undertaken. The inclusive longitudinal and transverse momentum distributions for the core fragments together with the cross sections have been measured for breakup on a carbon target. Momentum distributions for reactions on tantalum were also measured for a subset of nuclei. An extended version of the Glauber model incorporating second-order noneikonal corrections to the Jeukenne, Lejeune, and Mahaux parametrization of the optical potential has been used to describe the nuclear breakup, while the Coulomb dissociation is treated within first-order perturbation theory. The projectile structure has been taken into account via shell-model calculations employing the $psd$ interaction of Warburton and Brown. Both the longitudinal and transverse momentum distributions together with the integrated cross sections were well reproduced by these calculations and spin-parity assignments are thus proposed for ${}^{15}\mathrm{B},{}^{17}\mathrm{C},{}^{19–21}\mathrm{N},{}^{21,23}\mathrm{O},{}^{23–25}\mathrm{F}$. In addition to the large spectroscopic amplitudes for the $\nu 2s_{1∕2}$ intruder configuration in the $N=9$ isotones, ${}^{14}\mathrm{B}$ and ${}^{15}\mathrm{C}$, significant $\nu 2s_{1∕2}^2$ admixtures appear to occur in the ground state of the neighboring $N=10$ nuclei ${}^{15}\mathrm{B}$ and ${}^{16}\mathrm{C}$. Similarly, crossing the $N=14$ subshell, the occupation of the $\nu 2s_{1∕2}$ orbital is observed for ${}^{23}\mathrm{O}$, ${}^{24,25}\mathrm{F}$. Recent claims of a modified shell structure for ${}^{23}\mathrm{O}$ are investigated and the original suggestion of a ground state $J^{\pi }=1∕2^{+}$ is confirmed. Analysis of the longitudinal and transverse momentum distributions reveals that both carry spectroscopic information, often of a complementary nature. The general utility of high-energy nucleon removal reactions as a spectroscopic tool is also examined.

The cross sections of the processes ${}^4\mathrm{He}\left(\gamma ,p\right){}^3\mathrm{H}$ and ${}^4\mathrm{He}\left(\gamma ,n\right){}^3\mathrm{He}$ are calculated taking into account the full final state interaction via the Lorentz integral transform method. This is the first consistent microscopic calculation beyond the three-body breakup threshold. The results are obtained with a semirealistic central nucleon-nucleon potential including also the Coulomb force. The cross sections show a pronounced dipole peak at $27\text{MeV}$ which lies within the rather broad experimental band. At higher energies, where experimental uncertainties are considerably smaller, one finds a good agreement between theory and experiment. The calculated sum of three- and four-body photodisintegration cross sections is also listed and is in fair agreement with the data.

Variations in the nuclear mean field, in neutron-rich nuclei, are investigated within the framework of the nuclear shell model. The change is identified to originate mainly from the monopole part of the effective two-body proton-neutron interaction. Applications for the low-lying states in odd-$A$ Cu nuclei are presented. We compare the results using both schematic and realistic forces. We also compare the monopole shifts with the results obtained from large-scale shell-model calculations, using the same realistic interaction, in order to study two-body correlations beyond the proton mean-field variations.

Modifications of the infinite square well E(5) and X(5) descriptions of transitional nuclear structure are considered. The eigenproblem for a potential with linear sloped walls is solved. The consequences of the introduction of sloped walls and of a quadratic transition operator are investigated.

Accurately calibrated (or “best fit”) relativistic mean-field models are used to compute the distribution of isoscalar-monopole strength in ${}^{90}\mathrm{Zr}$ and ${}^{208}\mathrm{Pb}$, and the isovector-dipole strength in ${}^{208}\mathrm{Pb}$ using a continuum random-phase-approximation approach. It is shown that the distribution of isoscalar-monopole strength in ${}^{208}\mathrm{Pb}$—but not in ${}^{90}\mathrm{Zr}$—is sensitive to the density dependence of the symmetry energy. This sensitivity hinders the extraction of the compression modulus of symmetric nuclear matter from the isoscalar giant monopole resonance (ISGMR) in ${}^{208}\mathrm{Pb}$. Thus, one relies on ${}^{90}\mathrm{Zr}$, a nucleus with both a small neutron-proton asymmetry and a well developed ISGMR peak, to constrain the compression modulus of symmetric nuclear matter to the range $K=\left(248\pm 8\right)\text{MeV}$. In turn, the sensitivity of the ISGMR in ${}^{208}\mathrm{Pb}$ to the density dependence of the symmetry energy is used to constrain its neutron skin to the range $R_n-R_p\lesssim 0.22\text{fm}$. The impact of this result on the enhanced cooling of neutron stars is briefly addressed.