With the aim to obtain information on the $E1\mathrm{}$ and $M1\mathrm{}$ photon strength functions at $\gamma$-ray energies below the neutron separation energy, we studied two-step $\gamma$ cascades following the capture of thermal neutrons in ${}^{107}\mathrm{Ag}.$ For this purpose, we undertook an experiment with the dedicated facility for two-step $\gamma$ cascades at the Řež research reactor. The obtained data were discussed in conjunction with previous results from resonance neutron capture measurements with the same isotope, obtained at the GELINA facility of the Institute for Reference Materials and Measurements. The cascade $\gamma$ decay of the ${}^{108}\mathrm{Ag}$ compound nucleus has been simulated with the aid of the Monte Carlo algorithm DICEBOX assuming several models for photon strength functions. To interpret the results of the experiments, the outcome from these simulations was confronted with the observed cascade-related quantities. The results indicate that the $E1\mathrm{}$ photon strength function below the neutron binding energy is suppressed with respect to the conventional Brink-Axel model and that the $M1\mathrm{}$ and/or possibly $E2\mathrm{}$ photon strengths may play an important role in the decay of compound nucleus at excitations below $\approx 3\mathrm{MeV}.$

A study of the ${}^7\mathrm{Li}{(}^9\mathrm{Be}{,}^4{\mathrm{He}}^{10}\mathrm{Be}{)}^2\mathrm{H}$ reaction at $E_{\mathrm{beam}}=70\mathrm{}\mathrm{MeV}$ has been performed using resonant particle spectroscopy techniques and provides the first measurements of α-decaying states in ${}^{14}\mathrm{C}.$ Excited states are observed at 14.7, 15.5, 16.4, 18.5, 19.8, 20.6, 21.4, 22.4, and 24.0 MeV. The experimental technique was able to resolve decays to the various particle bound states in ${}^{10}\mathrm{Be}$ and provides evidence for the preferential decay of the high energy excited states into states in ${}^{10}\mathrm{Be}$ at ∼6 MeV. The decay processes are used to indicate the possible cluster structure of the ${}^{14}\mathrm{C}$ excited states.

In this paper, we report our systematic calculations of angular momentum I ground state probabilities $P\left(I\right)\mathrm{}$ of boson systems with spin l in the presence of random two-body interactions. It is found that the $P\left(0\right)\mathrm{}$ dominance is usually not true for a system with an odd number of bosons, while it is valid for an even number of bosons, which indicates that the $P\left(0\right)\mathrm{}$ dominance is partly connected to the even number of identical particles. It is also noticed that the ${P(I}_{\max })$’s of bosons with spin l do not follow the $1/N$ $(N=l+1,$ referring to the number of independent two-body matrix elements) relation. The properties of the $P\left(I\right)\mathrm{}$’s obtained in boson systems with spin l are discussed.

We extend a recent calculation of the nuclear energy density functional in the systematic framework of chiral perturbation theory by computing the isovector spin-orbit terms: $\left(\overrightarrow{\nabla }{\rho }_p-\overrightarrow{\nabla }{\rho }_n\right)\cdot \left(J_p-J_n{)G}_{\mathrm{so}}{(k}_f\right)+\left(J_p-J_n{)}^2{G}_J{(k}_f\right).\mathrm{}$ The calculation includes the one-pion exchange Fock diagram and the iterated one-pion exchange Hartree and Fock diagrams. From these few leading order contributions in the small momentum expansion one obtains already a good equation of state of isospin-symmetric nuclear matter. We find that the parameter-free results for the (density-dependent) strength functions $G_{\mathrm{so}}{(k}_f)$ and $G_J{(k}_f)$ agree fairly well with that of phenomenological Skyrme forces for densities $\rho >{\rho }_0/10.\mathrm{}$ At very low densities, a strong variation of the strength functions $G_{\mathrm{so}}{(k}_f)$ and $G_J{(k}_f)$ with density sets in. This has to do with chiral singularities $m_{\pi }^{-1}$ and the presence of two competing small mass scales $k_f$ and $m_{\pi }.$ The novel density dependencies of $G_{\mathrm{so}}{(k}_f)$ and $G_J{(k}_f),$ as predicted by our parameter-free (leading order) calculation, should be examined in nuclear structure calculations.

We study the conditions for the generation and the dynamical evolution of embryonic overcritical vapor bubbles in an overheated asymmetric nuclear matter. We show that the Fermi-surface distortion and memory effects significantly hinder the growth of the bubbles. Moreover, the growth of the bubble is accompanied by characteristic oscillations of its radius R. The characteristic energy E, the damping parameter $\Gamma ,$ and the instability growth rate parameter $\zeta ,$ depend on the relaxation time $\tau .$ The characteristic oscillations disappear in the short relaxation time limit $\overrightarrow{\tau }0.$ Our approach ignores the fluctuations of the particle numbers in the bubble region and the finite diffuse layer of the bubble. The minimum size of the critical radius $R^{*}$ for which our approach applies is determined by the condition ${a/R}^{*}\ll 1,$ where $a=0.5\mathrm{}–1\mathrm{fm}$ is the temperature-dependent surface thickness of the bubble.

We present results from a joint theoretical and experimental study of inclusive quasifree electrofission of ${}^{238}\mathrm{U}.$ The off-shell cross sections for the quasifree reaction stage have been calculated within the plane wave impulse approximation with distortion corrections included in the effective momentum approximation. Proton and neutron single-particle momentum distributions were calculated in the macroscopic-microscopic approach. The fissility for proton and neutron single hole excited states of the residual nuclei ${}^{237}\mathrm{Pa}$ and ${}^{237,238}\mathrm{U}$ was calculated within the compound nucleus model. Final state interaction corrections to residual nucleus excitation energy were calculated using the imaginary part of the optical potential. The total inclusive electrofission cross section was measured with high absolute precision, and all principal partial contributions are analyzed, in particular, the quasifree one.

Using the statistical model, we analyze deexcitation channels in excited neutron-deficient compound nuclei produced in fusion reactions with heavy ions. The results obtained without special adjustment to the selected evaporation channels are in good agreement with the experimental data near the maxima of excitation functions. The fusion probability, which is calculated with the dinuclear system model, is an important ingredient of the excitation function. Optimal reactions and evaporation channels for the production of neutron-deficient isotopes far from the stability line are proposed.

The two-proton overlap functions for the ${}^{16}\mathrm{O}{(e,e}^{\prime }{pp)}^{14}\mathrm{C}$ reaction are calculated on the basis of a two-body density matrix obtained within the Jastrow correlation method which incorporates short-range correlations. The resulting overlap functions are applied to calculate cross sections of the ${}^{16}\mathrm{O}{(e,e}^{\prime }{pp)}^{14}\mathrm{C}$ reactions leading to the $0^{+}$ ground and the $1^{+}$ (11.3-MeV) excited states of the residual nucleus. The results are compared with the cross sections calculated with different theoretical treatments of the two-nucleon overlap functions.

The investigation of statistical and direct aspects related to the $(\gamma ,n)$ and $(\gamma ,np)$ decay channels of ${}^{64}\mathrm{Zn}$ in the giant dipole resonance (GDR) and quasideuteron (QD) energy regions was performed by a trial function fitting to the respective $\mathrm{}(e,n)\mathrm{}$ and $\mathrm{}(e,np)\mathrm{}$ electrodisintegration yields measured by residual activity. The trial function incorporated the GDR and QD models to describe the initial photoabsorption mechanism and the geometry dependent hybrid exciton model used in the ALICE/LIVERMORE-82 code to calculate the relevant branching ratios, with the $E1\mathrm{}$ virtual photon spectra being calculated in the distorted wave Born approximation. We compared our results for the $(\gamma ,n)$ cross section with other existing experimental measurements, and the long-standing normalization issue among different laboratories was revisited and addressed. We obtained for the first time the absolute $(\gamma ,np)$ cross section from threshold to 60 MeV. We succeeded in separating statistical and direct contributions of the $(\gamma ,np)$ process, the latter being remarkably well described by the QD model in the interval 40–60 MeV. A possible direct contribution for the $(\gamma ,n)$ decay in the GDR is also addressed. Finally, the total photoabsorption cross section of ${}^{64}\mathrm{Zn}$ was reevaluated up to 21 MeV, and the results were compared with previous estimates performed by other groups.

We present a unified description of the vector meson and dilepton production in elementary and in heavy ion reactions. The production of vector mesons $(\rho ,\omega )$ is described via the excitation of nuclear resonances R. The theoretical framework is an extended vector meson dominance model (eVMD). The treatment of the resonance decays $R\mapsto \mathrm{NV}$ with arbitrary spin is covariant and kinematically complete. The eVMD thereby includes excited vector meson states in the transition form factors. This ensures correct asymptotics and provides a unified description of photonic and mesonic decays. The resonance model is successfully applied to the $\omega$ production in $p-p$ reactions. The same model is applied to the dilepton production in elementary reactions $(p-p,p-d).\mathrm{}$ Corresponding data are well reproduced. However, when the model is applied to heavy ion reactions in the BEVALAC/SIS energy range, the experimental dilepton spectra measured by the DLS Collaboration are significantly underestimated at small invariant masses. As a possible solution of this problem, the destruction of quantum interference in a dense medium is discussed. A decoherent emission through vector meson decays enhances the corresponding dilepton yield in heavy ion reactions. In the vicinity of the $\rho /\omega$ peak, the reproduction of the data requires further a substantial collisional broadening of the $\rho$ and, in particular, of the $\omega$ meson.

We present a new method of obtaining time-dependent matrix elements of the electromagnetic pulse produced by a highly relativistic projectile. These matrix elements are used in a coupled-channel calculation to predict the cross sections for population of one- and two-phonon states of the giant dipole resonance. Comparisons are made with the predictions of the long-wavelength and Born approximations.

We have analyzed the latest NA50 data on $J/\psi$ production in $\mathrm{pA}$ and $\mathrm{AA}$ collisions. The $J/\psi$ production is assumed to be a two step process, (i) formation of $c\overline{c}$ pairs, perturbatively calculable, and (ii) formation of $J/\psi$ from the pair, a nonperturbative process which is conveniently parametrized. In a nuclear medium, as the $c\overline{c}$ pair passes through the nuclear medium, it gains relative square momentum and some of the pairs can gain enough square momentum to cross the threshold for open charm meson, leading to suppression in nuclear medium. A few parameters of the model were fixed from the latest high statistics NA50 $\mathrm{pA}$ and NA38 SU total $J/\psi$ cross sectional data. The model then reproduces the centrality dependence of $J/\psi$ over Drell-Yan ratio in $200\mathrm{GeV}/c$ $\mathrm{S}+\mathrm{U}$ and $158\mathrm{GeV}/c$ $\mathrm{Pb}+\mathrm{Pb}$ collisions.

Charge balance functions provide insight into critical issues concerning hadronization and transport in heavy-ion collisions by statistically isolating charge/anticharge pairs that are correlated by charge conservation. However, distortions from residual interactions and unbalanced charges cloud the observable. Within the context of simple models, the significance of these effects is studied by constructing balance functions in both relative rapidity and invariant relative momentum. Methods are presented for eliminating or accounting for these distortions.

Within the impulse approximation, we derive expressions for the amplitude of deeply virtual Compton scattering on spinless nuclei in terms of the generalized parton distributions of the nucleon. As an application, nuclear effects in the beam-charge and single-spin asymmetries are discussed.

We apply the perturbative chiral quark model to the $\gamma \overrightarrow{N}\Delta$ transition. The four-momentum dependence of the respective transverse helicity amplitudes $A_{1/2}$ and $A_{3/2}$ is determined at one loop in the pseudoscalar Goldstone boson fluctuations. Inclusion of excited states in the quark propagator is shown to result in a reasonable description of the experimental values for the helicity amplitudes at the real-photon point.

The results of a search for $K^{-}\overrightarrow{p}{\pi }^0{\pi }^0{\pi }^0\Lambda$ (where the $3{\pi }^0$’s are not from $\eta$-meson decay) are presented. The data were obtained with the Crystal Ball spectrometer at eight beam momenta from 514 to $750\mathrm{MeV}/c.\mathrm{}$ For the six beam momenta below $p_{K^{-}}=714\mathrm{}\mathrm{MeV}/c,$ no signal was found; the 90% C.L. upper limit obtained for the $K^{-}\overrightarrow{p}3{\pi }^0\Lambda$ total cross section ${\sigma }_t$ varies between 2 and $7\mu \mathrm{b}.$ This small upper limit is indicative that spontaneous ${\pi }^0$ emission is insignificant, since the $K^{-}\overrightarrow{p}{\pi }^0{\pi }^0{\pi }^0\Lambda$ threshold is at $p_{K^{-}}=397\mathrm{}\mathrm{MeV}/c.\mathrm{}$ A signal was observed only at $p_{K^{-}}=750\mathrm{}\mathrm{MeV}/c,$ with ${\sigma }_t=25\mathrm{}\pm 7\mu \mathrm{b}.$ These results can be explained only if triple ${\pi }^0$ production goes predominantly by hyperon resonance deexcitation, $K^{-}\overrightarrow{p}{\Sigma }^{*}\to {\pi }^0{\Lambda }^{*}.$ There are several candidates for the ${\Sigma }^{*}$ but only one for the ${\Lambda }^{*},$ namely, the $\Lambda \mathrm{}\left(1520\right)\mathrm{}{\frac{3}{2}}^{-},$ as the threshold for $K^{-}\overrightarrow{p}{\pi }^0\Lambda \mathrm{}\left(1520\right)\mathrm{}$ is at $p_{K^{-}}=704\mathrm{}\mathrm{MeV}/c.\mathrm{}$

The nucleon spin structure function $g_1$ is studied based on a simple constituent quark model. Effects of low-lying nucleon resonances are discussed and the onset of Bloom-Gilman quark-hadron duality for the nucleon spin structure function is estimated. Our result qualitatively shows that in the range of $Q^2<0.75\mathrm{}{\mathrm{GeV}}^2,$ quark-hadron duality for $g_1^p$ is violated.

We report a study of the $\beta$ decay of ${}^{62}\mathrm{Ga},$ whose dominant branch is a superallowed $0^{+}\to 0^{+}$ transition to the ground state of ${}^{62}\mathrm{Zn}.$ We find the total half-life to be $115.84\pm 0.25\mathrm{ms}.$ This is the first time that the ${}^{62}\mathrm{Ga}$ half-life has been measured with a purified source. We find that $(0.120\mathrm{}\pm 0.021)\%$ of the $\beta$ decays are followed by $\gamma$ cascades that pass through the ${}^{62}\mathrm{Zn}$ $2^{+}$ first excited state at 0.954 MeV. The branching ratio to the first-excited $0^{+}$ state in ${}^{62}\mathrm{Zn}$ at 2.33 MeV is $<0.043\%.\mathrm{}$ We conclude that the branching ratio for the superallowed transition is ${99.85}_{-0.15}^{+0.05\mathrm{}}\%.\mathrm{}$

This paper shows that ultrastrong magnetic fields (such as those of magnetars) and dense astrophysical plasmas can reduce the half-life of $\alpha$-decaying nuclei by many orders of magnitude. In such environments, the conventional Geiger-Nuttall law is modified so that all relevant half-lives are shifted to dramatically lower values.

In ultraperipheral relativistic deuteron on heavy-ion collisions, a photon emitted from the heavy nucleus may dissociate the deuterium ion. We find deuterium breakup cross sections of 1.38 b for deuterium-gold collisions at a center of mass energy of 200 GeV per nucleon, as studied at the Relativistic Heavy Ion Collider, and 2.49 b for deuterium-lead collisions at a center-of-mass energy of 6.2 TeV, as proposed for the Large Hadron Collider (LHC). This cross section includes an energy-independent 140-mb contribution from the hadronic diffractive dissociation. At the LHC, the cross section is as large as that of hadronic interactions. The estimated error is 5%. Deuteron dissociation could be used as a luminosity monitor and a “tag” for moderate impact-parameter collisions.