With the self-consistent 3D-cranking model, the ground-state rotational band in ${}^{24}\mathrm{Mg}$ is analyzed. The role of triaxial deformation is discussed, in particular in a description of the observed two $I^{\pi }=8^{+}$ states.

We show that the FRLDM model currently being used in macroscopic-microscopic fission-barrier calculations gives a rather poor agreement with measured charge radii. Considerable improvement in this respect can be made by adjusting the diffuseness parameter b.

We discuss the meaning of Zipf's law in nuclear multifragmentation. We remark that Zipf's law is a consequence of a power-law fragment size distribution with exponent $\tau \simeq 2$. We also recall why the presence of such a distribution is not a reliable signal of a liquid-gas phase transition.

We investigate, in microcanonical multifragmentation models, the influence of the amount of energy dissipated in break-up fragments excitation on freeze-out volume determination. Assuming a limiting temperature that decreases with nuclear mass, we obtain for the Xe+Sn at 32 MeV/nucleon reaction a freeze-out volume that is almost half the one deduced using a constant limiting temperature.

We examine the energy dependence of single-meson photoproduction as it contributes to the Gerasimov-Drell-Hearn (GDH) sum rule. For photon energies above approximately 1 GeV, through the full resonance region, this contribution dominates the proton sum-rule integral. Over the same energy region, our single-pion contribution to the neutron sum rule also qualitatively follows a recent set of GDH data. The predicted neutral-pion contribution to the neutron sum rule is nearly zero above 1 GeV in this result. The SAID and Mainz (MAID) results are very different for a number of observables over this energy region.

We consider an exactly solvable Hamiltonian for bosons in one-dimension interacting through zero-range attractive forces, and construct a complete basis of its A-particle eigenstates. The structure of the single-particle spectral function in the removal domain is investigated, by taking the overlap of the A-particle ground state with the various excited states of the $(A-1)$ system. In particular we study the contribution to the spectral function of the different break-up channels in the $A-1$ continuum, and compare the results to general statements available in the literature. It is shown that the asymptotic behavior in coordinate space does not agree with conventional assumptions. The relation to recent $(e,e^{\text{'}}p)$ experiments at large values of missing energy and momentum is pointed out.

A dynamical interpretation of the well-known systematics for average total kinetic energy of fission fragments $\langle E_K\rangle$ over a wide range of the Coulomb parameter ($600<Z^2/A^{1/3}<2200$) is given. Different scission criteria traditionally employed in fission theory—at zero neck radius and at finite neck radius—have been applied in dynamical calculations. Both have resulted in a fairly good description of the dependence of $\langle E_K\rangle$ on the Coulomb parameter. The results of dynamical calculations of $\langle E_K\rangle$ within three-dimensional Langevin dynamics show that the mean distance between the centers of mass of nascent fragments at the scission configuration increases linearly with the parameter $Z^2/A^{1/3}$. This distance changes approximately from $2.35R_0$ for ${}^{119}\mathrm{Xe}$ to $2.6R_0$ for ${}^{256}\mathrm{Fm}$. In spite of this increase in mean distance between future fragments at scission, the linear dependence of $\langle E_K\rangle$ on the parameter $Z^2/A^{1/3}$ remains approximately valid over a wide range of the Coulomb parameter $Z^2/A^{1/3}$.

We study Gamow-Teller strength distributions in the neutron-deficient even isotopes ${}^{184-194}\mathrm{Pb}$ in a search for signatures of deformation. The microscopic formalism used is based on a deformed quasiparticle random-phase approximation (QRPA) approach, which involves a self-consistent quasiparticle deformed Skyrme Hartree-Fock (HF) basis and residual spin-isospin forces in both the particle-hole and particle-particle channels. By analyzing the sensitivity of the Gamow-Teller strength distributions to the various ingredients in the formalism, we conclude that the β decay of these isotopes could be a useful tool to look for fingerprints of nuclear deformation.

We investigate the effect of two-photon exchange processes upon the rms- and Zemach radii extracted from electron-proton scattering. We find that the changes are small and do not help to explain the discrepancy between experimental and calculated HFS in the hydrogen atom.

Recent measurements by the BRAHMS Collaboration of high-$p_T$ hadron production at forward rapidities at the BNL Relativistic Heavy Ion Collider found the relative production rate $(d\text{−}\mathrm{Au})/(p\text{−}p)$ to be suppressed rather than enhanced. Examining other known reactions (forward production of light hadrons, the Drell-Yan process, heavy flavor production, etc.), one notes that all of these display a similar property, namely, their cross sections in nuclei are suppressed at large $x_F$. Since this is the region where $x_2$ is minimal, it is tempting to interpret this as a manifestation of coherence or of a color glass condensate, whereas it is actually a simple consequence of energy conservation and takes place even at low energies. We demonstrate that in all these reactions there is a common suppression mechanism that can be viewed, alternatively, as a consequence of a reduced survival probability for large rapidity gap processes in nuclei, a Sudakov suppression, an enhanced resolution of higher Fock states by nuclei, or an effective energy loss that rises linearly with energy. Our calculations agree with the data.

Measured cross sections for the fusion of ${}^{64}\mathrm{Ni}$ with ${}^{64}\mathrm{Ni}$, ${}^{74}\mathrm{Ge}$, and ${}^{100}\mathrm{Mo}$ targets are analyzed in a coupled-channels approach. The data for the ${}^{64}\mathrm{Ni}$ target above 0.1 mb are reproduced by including couplings to the low-lying $2^{+}$ and $3^{-}$ states and the mutual and two-phonon excitations of these states. The calculations become more challenging as the fusing nuclei become softer and heavier, and excitations to multi-phonon states start to play an increasingly important role. Thus it is necessary to include up to four-phonon excitations to reproduce the data for the ${}^{64}\mathrm{Ni}+{}^{74}\mathrm{Ge}$ system. Similar calculations for ${}^{64}\mathrm{Ni}+{}^{100}\mathrm{Mo}$, and also for the symmetric ${}^{74}\mathrm{Ge}+{}^{74}\mathrm{Ge}$ system, show large discrepancies with the data. Possible ways to improve the calculations are discussed.

In an experiment at the SISSI/LISE3 facility of GANIL, we have studied the decay of the two proton-rich nuclei ${}^{45}\mathrm{Fe}$ and ${}^{48}\mathrm{Ni}$. We identified 30 implantations of ${}^{45}\mathrm{Fe}$ and observed for the second time four implantation events of ${}^{48}\mathrm{Ni}$. In 17 cases, ${}^{45}\mathrm{Fe}$ decays by two-proton emission with a decay energy of 1.154(16) MeV and a half-life of $T_{1/2}={1.6}_{-0.3}^{+0.5}$ ms. The observation of ${}^{48}\mathrm{Ni}$ and of its decay allows us to deduce a half-life of $T_{1/2}={2.1}_{-0.7}^{+2.1}$ ms. One out of four decay events is completely compatible with two-proton radioactivity and may therefore indicate that ${}^{48}\mathrm{Ni}$ has a two-proton radioactivity branch. We discuss all information now available on two-proton radioactivity for ${}^{45}\mathrm{Fe}$ and ${}^{48}\mathrm{Ni}$ and compare it to theoretical models.

Nuclear structure of the neutron rich ${}^{25-29}\mathrm{Ne}$ nuclei has been investigated through the in-beam γ-ray spectroscopy technique using fragmentation reactions of both stable and radioactive beams. Level schemes have been deduced for these Ne isotopes. In order to examine the importance of intruder fp configurations, they are compared to shell model calculations performed either in the restricted sd or in the larger sdpf valence space. The ${}^{25,26}\mathrm{Ne}$ and ${}^{27}\mathrm{Ne}$ nuclei were found to be in agreement with the sd shell model calculations, whereas ${}^{28}\mathrm{Ne}$ exhibits signatures of the intruder fp shell contribution.

We report an extension of the source imaging method for analyzing three-dimensional sources from three-dimensional correlations. Our technique consists of expanding the correlation data and the underlying source function in spherical harmonics and inverting the resulting system of one-dimensional integral equations. With this strategy, we can image the source function quickly, even with the finely binned data sets common in three-dimensional analyses.

High-spin states in the doubly odd nucleus ${}^{160}\mathrm{Tm}$ have been investigated using the ${}^{130}\mathrm{Te}$(${}^{35}\mathrm{Cl}$,5n) reaction and the Euroball γ-ray detector array. The previously established rotational structures in ${}^{160}\mathrm{Tm}$ were extended, leading to the first observation of the second $(h_{11/2}){}^2$ proton band crossing in this nucleus. This crossing is found to occur at a higher rotational frequency in ${}^{160}\mathrm{Tm}$ than in lighter Tm isotopes. This trend resembles that of the first $(h_{11/2}){}^2$ proton band crossing found in neighboring Er nuclei and is associated with a predicted increase in deformation as a function of neutron number in these isotopes.

Evolution of quadrupole deformations in sd- and pf-shell nuclei with mass $A=18~56$ is studied by using deformed Skyrme Hartree-Fock model with pairing correlations. We point out that the quadrupole deformations of the nuclei with the isospin $T=0$ and $T=1$ show strong mass number dependence as a clear manifestation of dynamical evolution of deformation in nuclear many-body systems. The competition between the deformation driving particle-vibration coupling and the closed-shell structure is shown in a systematic study of the ratios between the proton and neutron deformations in nuclei with $T=\left|T_z\right|=1$. Calculated quadrupole and hexadecapole deformations are compared with shell model results and available experimental data. A relation between the skin thickness and the intrinsic $Q_2$ moments is also discussed.

Energies, total and partial widths, and reduced width amplitudes of ${}^8\mathrm{Be}$ resonances up to an excitation energy of 26 MeV are extracted from a coupled-channel analysis of experimental data. The presence of an extremely broad $J^{\pi }=2^{+}$ “intruder” resonance is confirmed, and new $1^{+}$ and very broad $4^{+}$ resonances are discovered. A previously known 22-MeV $2^{+}$ resonance is likely resolved into two resonances. The experimental $J^{\pi }T=3^{(+)}$? resonance at 22 MeV is determined to be $3^{-}0$, and the experimental $1^{-}$? (at 19 MeV) and $4^{-}$? resonances are determined to be isospin 0.

A survey of pairing properties of nucleonic matter is presented that includes the off-shell propagation associated with short-range and tensor correlations. For this purpose, the gap equation has been solved in its most general form employing the complete energy and momentum dependence of the normal self-energy contributions. The latter correlations include the self-consistent calculation of the nucleon self-energy that is generated by the summation of ladder diagrams. This treatment preserves the conservation of particle number unlike approaches in which the self-energy is based on the Brueckner-Hartree-Fock approximation. A huge reduction in the strength as well as temperature and density range of ${}^3{S}_1\text{−}{}^3{D}_1$ pairing is obtained for nuclear matter as compared to the standard BCS treatment. Similar dramatic results pertain to ${}^1{S}_0$ pairing of neutrons in neutron matter.

The dependence on the single-particle states of the pairing matrix elements of the Gogny force and of the bare low-momentum nucleon-nucleon potential $v_{\mathrm{low}\text{−}k}$—designed so as to reproduce the low-energy observables avoiding the use of a repulsive core—is studied for a typical finite, superfluid nucleus (${}^{120}\mathrm{Sn}$). It is found that the matrix elements of $v_{\mathrm{low}\text{−}k}$ follow closely those of $v_{\mathrm{Gogny}}$ on a wide range of energy values around the Fermi energy $e_F$, those associated with $v_{\mathrm{low}\text{−}k}$ being less attractive. This result explains the fact that around $e_F$ the pairing gap ${\Delta }_{\mathrm{Gogny}}$ associated with the Gogny interaction (and with a density of single-particle levels corresponding to an effective k mass $m_k\approx 0.7\hspace{1em}m$) is a factor of about 2 larger than ${\Delta }_{\mathrm{low}\text{−}k}$, being in agreement with ${\Delta }_{\exp }=1.4$ MeV. The exchange of low-lying collective surface vibrations among pairs of nucleons moving in time-reversal states gives rise to an induced pairing interaction $v_{\mathrm{ind}}$ peaked at $e_F$. The interaction $(v_{\mathrm{low}\text{−}k}+v_{\mathrm{ind}})\hspace{1em}{Z}_{\omega }$ arising from the renormalization of the bare nucleon-nucleon potential and of the single-particle motion (ω-mass and quasiparticle strength $Z_{\omega }$) associated with the particle-vibration coupling mechanism, leads to a value of the pairing gap at the Fermi energy ${\Delta }_{\mathrm{ren}}$ that accounts for the experimental value. An important question that remains to be studied quantitatively is to what extent ${\Delta }_{\mathrm{Gogny}}$, which depends on average parameters, and ${\Delta }_{\mathrm{ren}}$, which explicitly depends on the parameters describing the (low-energy) nuclear structure, display or not a similar isotopic dependence and whether this dependence is borne out by the data.