We prove that a relativistic Coulomb excitation calculation in which the classical electromagnetic field of the projectile is used to induce transitions between target states gives the same target transition amplitudes, to all orders of perturbation theory, as would a calculation in which the interaction between projectile and target is mediated by a quantized electromagnetic field.

Based on the UrQMD (ultrarelativistic quantum molecular dynamics) model, we have investigated the influence of the symmetry potential on the negatively and positively charged $\pi$ and $\Sigma$ hyperon production ratios in heavy ion collisions at the SIS (SchwerIonen Synchrotron) energies. We find that, in addition to ${\pi }^{-}/{\pi }^{+}$ ratio, the ${\Sigma }^{-}/{\Sigma }^{+}$ ratio can be taken as a sensitive probe for investigating the density dependence of the symmetry potential of nuclear matter at high densities (1–4 times normal baryon density). This sensitivity of the symmetry potential to both the ${\pi }^{-}/{\pi }^{+}$ and ${\Sigma }^{-}/{\Sigma }^{+}$ ratios is found to depend strongly on the incident beam energy. Furthermore, the ${\Sigma }^{-}/{\Sigma }^{+}$ ratio is shown to carry the information about the isospin-dependent part of the $\Sigma$ hyperon single-particle potential.

Methods are set forth for determining the hadron electromagnetic structure in the sub-$N\stackrel{̲}{N}$-threshold timelike region of the virtual-photon “mass” and for investigating the nucleon weak structure in the spacelike region from experimental data on the process $\pi N\to e^{+}{e}^{-}N$ at low energies. These methods are formulated using the unified description of photoproduction, electroproduction, and inverse electroproduction of pions in the first resonance region in the framework of the dispersion-relation model and on the basis of the model-independent properties of inverse electroproduction. Applications of these methods are also shown.

The pion- and photon-induced reactions for the final states $\gamma N,\pi N,2\pi N,\eta N$, and $\omega N$ are studied within a coupled-channel effective Lagrangian approach in the energy region from the pion threshold up to 2 GeV. To investigate the role of the nucleon resonances in the different reactions we include all known states with spin $\text{−}1/2$, $\text{−}3/2$, and $\text{−}5/2$ and masses below 2 GeV. We find a strong contribution from the $D_{15}(1675)$ resonance to the $\pi N\to \omega N$ reaction. While the $F_{15}(1680)$ state only slightly influences the $\omega$ meson production in the $\pi N$ scattering its role is enhanced in the ω photoproduction due to the large electromagnetic coupling of this resonance. We predict the beam asymmetry ${\Sigma }_X$ to be a negative in the $\gamma p\to \omega p$ reaction near to the threshold. Above the 1.85 GeV the asymmetry is found to change its sign and becomes positive at forward directions. The presented findings can be experimentally tested at GRAAL, CLAS, and CB-ELSA facilities.

The $\alpha \text{−}d$ cluster structure of ${}^6\mathrm{Li}$ has been extensively investigated in the past few decades. In particular the width of the α momentum distribution in ${}^6\mathrm{Li}$ has been studied as a function of the transferred momentum. These investigations are now reviewed and updated after recent experiments. Trojan horse method applications are also discussed because the momentum distribution of the spectator particle inside the Trojan horse nucleus is a necessary input for this method. The impact of the width (FWHM) variation in the extraction of the astrophysical $S(E)$ factor is discussed for the ${}^6\mathrm{Li}$$(d,\alpha )$${}^4\mathrm{He}$ reaction.

Two particle correlations between identified meson and baryon trigger particles with $2.5<p_T<4.0\mathrm{GeV}/c$ and lower $p_T$ charged hadrons have been measured at midrapidity by the PHENIX experiment at RHIC in $p+p,d+\mathrm{Au}$, and $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200\mathrm{GeV}$. In noncentral $\mathrm{Au}+\mathrm{Au}$ collisions, the probability of finding a hadron near in azimuthal angle to the trigger particles is almost identical for mesons and baryons and significantly higher than in $p+p$ collisions. The associated yields for trigger baryons decrease in the most central collisions, consistent with some baryon production by thermal recombination in addition to hard scattering.

We have measured the total intensity of K x rays relative to 129.4-keV γ rays from decay of the second excited state in ${}^{191}\mathrm{Ir}$. This ($M1+E2$) transition was observed following the β decay of 15.4-d ${}^{191}\mathrm{Os}$. Our measured ratio yields the result ${\alpha }_K{\omega }_K=2.044(11)$. When combined with a recent measurement of the same ratio for the 80.2-keV $M4$ transition from ${}^{193}\mathrm{Ir}{}^m$, this result strongly confirms the need for the K-shell hole to be included in calculations of internal-conversion coefficients ${\alpha }_K$. Since the ${\alpha }_K$ value calculated for the ${}^{191}\mathrm{Ir}$ transition is virtually independent of the hole treatment, our result also yields a model-independent value for the iridium fluorescence yield, ${\omega }_K=0.954(9)$.

The spin-orbit two-body interaction has been used for a long time in nuclear structure studies and is unique. In contrast, two different expressions are used in nuclear scattering studies. One of them is stronger when the eigenvalues of $(\ell ·\sigma )$ of the two particles involved are opposite to each other, such as the interaction used in nuclear structure studies for an even parity excitation. This expression of the spin-orbit interaction can be qualified as “normal” in view of the similar behavior in these two applications. The other expression of the spin-orbit interaction involves the sum of these two eigenvalues.

The nuclide ${}^{17}\mathrm{Ne}$ is studied theoretically in a three-body ${}^{15}\mathrm{O}+p+p$ model. We demonstrate that the experimental condition for existence of a proton halo in ${}^{17}\mathrm{Ne}$ can be reasonably quantified in terms of $s/d$ configuration mixing. We discuss experimental evidence for a proton halo in ${}^{17}\mathrm{Ne}$ and define which kind of experimental data could elucidate this issue.

The absolute and the relative quadrupole shape invariants $q_3$ and $K_3$ provide a model independent measure of triaxiality for β-rigid nuclei. We will show that one can obtain approximate values of $q_3$ and $K_3$ by analytical formulas involving only few observables. These formulas allow one to get a—model independent—error for these approximate values. The approximations which are made will be shown to hold within a few percent both in the rigid triaxial rotor model and the interacting boson model. The shape parameter $K_3$ is given for an exemplary set of nuclei and is translated into effective values of the geometrical deformation parameters β and γ.

The high-spin structures of the ${}^{108}\mathrm{Pd}$ nucleus have been studied with the ${}^{100}\mathrm{Mo}({}^{11}\mathrm{B},p2n\gamma )$ reaction at 43 MeV incident energy. $\gamma \text{−}\gamma \text{−}t,\gamma \text{−}\gamma$-charged-particle coincidences and directional correlation ratios were measured using the SACI-PERERE γ spectrometer formed by four Compton suppressed HPGe detectors and a $4\pi$ charged-particle ancillary detector system. Recent results for the γ-vibrational band and the $\nu h_{11/2}\otimes \nu (g_{7/2},d_{5/2})$ negative parity structures have been confirmed and complemented. A new band tentatively based on the second lowest $(\nu h_{11/2})$ excitation has been observed.

The available spectroscopic data for nuclei middle and second half of the $1f_{7/2}$ shell are well reproduced by shell-model calculations. For natural parity states of several odd-A nuclei, a comparison of shell-model calculations in the full pf configuration space with the Nilsson diagram and particle-rotor predictions shows that prolate strong coupling applies at low excitation energy. Multiquasiparticle rotational bands and, in some cases, band crossings have been revealed. Coriolis decoupling effects are observed only in nuclei at the beginning of the shell. The ground state bands experience a change from a collective to a noncollective regime, approaching the termination in the $1f_{7/2}^n$ space. Similar features are observed in the even-even $N=Z$ nuclei ${}^{48}\mathrm{Cr}$ and ${}^{52}\mathrm{Fe}$ and $N=Z+2$ nuclei ${}^{46}\mathrm{Ti}$ and ${}^{50}\mathrm{Cr}$. Evidence of the vibrational γ band is discussed in the $N=Z$ nuclei. A brief review is also presented for unnatural parity levels.

We propose a schematic model with which the discretization of the continuum can be easily tested. The model is based on pairing equations for nuclei formed of a core plus two neutrons and is applied to ${}^6\mathrm{He}$, for which the continuum is very important since ${}^5\mathrm{He}$ is unbound. The results show that the discretization of the continuum underestimates the pairing energy by only a few percents.

We briefly reviewed and summarized the experimental study on $\beta$-delayed proton decays published by our group over the last 8 years, namely the experimental observation of $\beta$-delayed proton decays of nine new nuclides in the rare-earth region near the proton drip line and five nuclides in the mass 90 region with $N~Z$ by utilizing the $p\text{−}\gamma$ coincidence technique in combination with a He-jet tape transport system. In addition, important technical details of the experiments were provided. The experimental results were compared to the theoretical predictions of some nuclear models, resulting in the following conclusions. (1) The experimental half-lives for ${}^{85}\mathrm{Mo},{}^{92}\mathrm{Rh}$, as well as the predicted “waiting point” nuclei ${}^{89}\mathrm{Ru}$ and ${}^{93}\mathrm{Pd}$ were 5–10 times longer than the macroscopic-microscopic model predictions of Möller et al. [At. Data Nucl. Data Tables $66,131(1997)$]. These data considerably influenced the predictions of the mass abundances of the nuclides produced in the rp process. (2) The experimental assignments of spin and parity for the drip-line nuclei ${}^{142}\mathrm{Ho}$ and ${}^{128}\mathrm{Pm}$ could not be well predicted by any of the nuclear models. Nevertheless, the configuration-constrained nuclear potential-energy surfaces calculated by means of a Woods-Saxon-Strutinsky method could reproduce the assignments. (3) The ALICE code overestimated by one or two orders of magnitude the production-reaction cross sections of the nine studied rare-earth nuclei, while the HIVAP code overestimated them by approximately one order of magnitude.

Excited states in the proton-rich $N=84$ isotones ${}_{72}^{156}{\mathrm{Hf}}_{84},{}_{73}^{157}{\mathrm{Ta}}_{84}$, and ${}_{74}^{158}{W}_{84}$ were observed using ${}^{102}\mathrm{Pd}({}^{58}\mathrm{Ni},\mathit{xp}2n)$ reactions at 270 MeV. γ rays were detected with the Gammasphere array of Compton-suppressed Ge detectors coupled with the Argonne fragment mass analyzer and were assigned to individual reaction channels using the recoil-decay tagging method. Prompt γ-ray cascades were associated with the α decay of both the ground state and the $8^{+}$ isomeric state in ${}^{156}\mathrm{Hf}$, the $h_{11/2}$ state in ${}^{157}\mathrm{Ta}$, and the $8^{+}$ isomeric state in ${}^{158}\mathrm{W}$. The level schemes constructed for ${}^{156}\mathrm{Hf},{}^{157}\mathrm{Ta}$, and ${}^{158}\mathrm{W}$ are compared with these of lighter $N=84$ isotones and are discussed within the framework of the shell model.

We investigated the prompt dipole γ-ray emission, related with entrance channel charge asymmetry effects, in the ${}^{32}\mathrm{S}$$+$${}^{100}\mathrm{Mo}$ and ${}^{36}\mathrm{S}$$+$${}^{96}\mathrm{Mo}$ fusion reactions at $E_{\mathrm{lab}}=196$ MeV and 214.2 MeV, respectively, with the aim to probe its evolution with incident energy. These reactions populate, through entrance channels having different charge asymmetries, the ${}^{132}\mathrm{Ce}$ compound nucleus at an excitation energy of 117 MeV with identical spin distribution. Fusion events were selected by detecting high-energy γ rays in coincidence with evaporation residues. The center-of-mass differential γ-ray multiplicity spectra of the considered reactions were found to be identical within the experimental uncertainties in the whole energy range. This result, associated with that reported for the same reaction pair at higher beam energy where a larger giant dipole resonance yield was evidenced for the more charge asymmetric system, implies an increasing trend of the prompt dipole γ-ray emission with incident energy. Calculations based on a collective bremsstrahlung analysis of the reaction dynamics are presented and compared with the experimental findings.

An extensive experimental survey of the features of the disassembly of a small quasiprojectile system with $A~36$, produced in the reactions of 47 MeV/nucleon ${}^{40}\mathrm{Ar}+{}^{27}\mathrm{Al}$, ${}^{48}\mathrm{Ti}$, and ${}^{58}\mathrm{Ni}$, has been carried out. Nuclei in the excitation energy range of 1–9 MeV/nucleon have been investigated employing a new method to reconstruct the quasiprojectile source. At an excitation energy ∼5.6 MeV/nucleon many observables indicate the presence of maximal fluctuations in the deexcitation processes. These include the normalized second moments of the Campi plot and normalized variances of the distributions of order parameters such as the atomic number of the heaviest fragment $Z_{\max }$ and the total kinetic energy. The evolution of the correlation of the atomic number of the heaviest fragment with that of the second heaviest fragment and a bimodality test are also consistent with a transition in the same excitation energy region. The related phase separation parameter, $S_p$, shows a significant change of slope at the same excitation energy. In the same region a Δ-scaling analysis for of the heaviest fragments exhibits a transition to Δ = 1 scaling, which is predicted to characterize a disordered phase. The fragment topological structure shows that the rank-sorted fragments obey Zipf's law at the point of largest fluctuations, providing another indication of a liquid gas phase transition. The Fisher droplet model critical exponent τ ∼ 2.3 obtained from the charge distribution at the same excitation energy is close to the critical exponent of the liquid gas phase transition universality class. The caloric curve for this system shows a monotonic increase of temperature with excitation energy and no apparent plateau. The temperature at the point of maximal fluctuations is $8.3\pm 0.5\text{MeV}$. Taking this temperature as the critical temperature and employing the caloric curve information we have extracted the critical exponents $\beta ,\gamma$, and σ from the data. Their values are also consistent with the values of the universality class of the liquid gas phase transition. Taken together, this body of evidence strongly suggests a phase change in an equilibrated mesoscopic system at, or extremely close to, the critical point.

The distribution of the largest fragment is studied in different regions of the lattice gas model phase diagram. We show that first- and second-order transitions can be clearly distinguished in the grancanonical ensemble, while signals typical of a continuous transition are seen inside the coexistence region if a mass conservation constraint is applied. Some possible implications of these findings for heavy-ion multifragmentation experiments are discussed.

Particle number fluctuations are studied in the microcanonical ensemble. For the Boltzmann statistics we deduce exact analytical formulas for the microcanonical partition functions in the case of noninteracting massless neutral particles and charged particles with zero net charge. The particle number fluctuations are calculated and we find that in the microcanonical ensemble they are suppressed in comparison to the fluctuations in the canonical and grand canonical ensembles. This remains valid in the thermodynamic limit too, so that the well-known equivalence of all statistical ensembles refers to average quantities, but does not apply to fluctuations. In the thermodynamic limit we are able to calculate the particle number fluctuations in the system of massive bosons and fermions when the exact conservation laws of both the energy and charge are taken into account.