The reaction ${}^{58}\mathrm{Ni}{(}^{32}\mathrm{S},\alpha 2p)$ at $E_{\mathrm{lab}}=135\mathrm{}\mathrm{MeV}$ was used to populate high-spin states in ${}^{84}\mathrm{Zr}.$ The complete GAMMASPHERE and MICROBALL arrays were used to obtain clean γ-γ-γ line shapes to be analyzed by the Doppler shift attenuation method and to determine 27 lifetimes in the ground-state band and in two excited bands. Side-feeding times were also measured by comparing the line shapes gated with transitions above and below the state under study. The deduced electric quadrupole moments for the ground-state band are consistent with a very slow reduction with frequency with values ranging between 2.4(3) and $2.0\left(1\right)e\mathrm{b}.$ The negative-parity bands feature also an approximate constancy of quadrupole moment with values similar to those in the ground-state band. Cranking calculations agree with this behavior in both parity bands and suggest an interpretation of the upper states in the ground-state band as part of a very slowly terminating band. Shell-dependent cranked Nilsson calculations explain a fourth γ cascade as pertaining to a noncollective structure terminating at ${I=20\mathrm{}}^{+}.$

The advanced time-delayed βγγ(t) method was used to measure lifetimes of the low-lying levels in ${}^{149}\mathrm{Ce}$ populated in the ${\beta }^{-}$ decay of ${}^{149}\mathrm{La}.$ The half-life of the $K^{\pi }{=3/2\mathrm{}}^{+}$ band head at 133.5 keV was measured as ${\mathrm{T}}_{1/2}=600\mathrm{}\left(100\right)\mathrm{}\mathrm{ps},$ yielding $|D_0|=0.034\mathrm{}\left(7\right)e\mathrm{fm}$ and $|D_0|=0.041\mathrm{}\left(5\right)e\mathrm{fm}$ for the $E1\mathrm{}$ transitions to the ${5/2}^{-}$ and ${3/2}^{-}$ members of the $K^{\pi }{=3/2\mathrm{}}^{-}$ ground state band, respectively. Furthermore, ${\mathrm{T}}_{1/2}<~120\mathrm{ps}$ was estimated for the $K^{\pi }{=3/2\mathrm{}}^{-}$ band head at 245.4 keV which yields the lower limit of $|D_0|>~0.05e\mathrm{fm}.$ No strong quenching of the $B\left(E1\mathrm{}\right)\mathrm{}$ rates in ${}^{149}\mathrm{Ce}$ was observed. Our results correct the previous lifetime measurements and allow us to extend the $D_0$ systematics in the exotic neutron-rich nuclei from the Ba-Nd region.

We propose a procedure to extract the probability for a valence particle being out of the binding potential from the measured nuclear asymptotic normalization coefficients. With this procedure, available data regarding the nuclear halo candidates are systematically analyzed and a number of halo nuclei are confirmed. Based on these results: we obtain a very relaxed condition for nuclear halo occurrence. Furthermore, we present the scaling laws for the dimensionless quantity $〈r^2〉{/R}^2$ of the nuclear halo in terms of the analytical expressions of the expectation value for the operator $r^2$ in a finite square-well potential.

We investigate the accuracy of several schemes to calculate ground-state correlation energies using the generator coordinate technique. Our test bed for the study is the sd-interacting boson model, equivalent to a six-level Lipkin-type model. We find that the simplified projection of a triaxial generator coordinate state using the $S_3$ subgroup of the rotation group is not very accurate in the parameter space of the Hamiltonian of interest. On the other hand, a full rotational projection of an axial generator coordinate state gives remarkable accuracy. We also discuss the validity of the simplified treatment using the extended Gaussian overlap approximation, and show that it works reasonably well when the number of boson is 4 or larger.

This paper establishes the case that the process of quasifree $\eta$ photoproduction from nuclei is an important tool to study medium modifications and changes to the elementary process $\gamma \overrightarrow{N}\eta N$ in the nuclear medium. We investigate the sensitivity of the differential cross section, recoil nucleon polarization, and the photon asymmetry to changes in the elementary amplitude, medium modifications of the resonance ${(S}_{11}{,D}_{13})$ masses, as well as nuclear target effects. All calculations are performed within a relativistic plane-wave impulse approximation formalism resulting in analytical expressions for all observables. Our results indicate that polarization observables are largely insensitive to nuclear target effects. Depending on the type of coupling, the spin observables do display a sensitivity to the magnitude of the $\eta \mathrm{NN}$ coupling constant. The polarization observables are identified to be the prime candidates to investigate the background processes and their medium modifications in the elementary process such as the $D_{13}$ resonance. Moreover, as a consequence of the large dominance in the differential cross section of the $S_{11}$ resonance, the quasifree differential cross section provides an exceptional instrument to study medium modifications to the $S_{11}$ resonance in such a manner that helps to distinguish between various models that attempt to understand the $S_{11}$ resonance and its distinctive position as the lowest lying negative parity state in the baryon spectrum.

We have studied the evolution and dilepton production of a chemically equilibrating quark-gluon system at finite baryon density. We found that due to the increase of the quark phase lifetime with increasing initial quark chemical potential and other factors, such as, higher initial temperature, larger gluon density, and gluon fusion or quark annihilation cross section, thermal charmed quarks provide a dominant contribution to the dilepton yield. This results in a significant enhancement of intermediate mass dilepton production.

The quasielastic electron scattering contributions to the ${(e,e}^{\prime })$ and ${(e,e}^{\prime }p)$ reactions for medium and heavy nuclei depend on the nucleon electric and magnetic form factors in the nucleus. We investigate experimental data for the ${(e,e}^{\prime })$ reaction taken at SLAC on ${}^{12}\mathrm{C},$ ${}^{56}\mathrm{Fe},$ and ${}^{197}\mathrm{Au}$ at four-momentum transfers up to $0.28(\mathrm{GeV}{/c)}^2$ and for the ${(e,e}^{\prime }p)$ reaction at Jefferson Lab on ${}^{16}\mathrm{O}$ at four-momentum transfer of $0.8(\mathrm{GeV}{/c)}^2.$ Using a relativistic mean field “single-particle” theoretical model that successfully describes experimental data at lower energies and momentum transfers, we find no evidence for a modification of the nucleon form factors from their free space values for the inclusive ${(e,e}^{\prime })$ reactions and suggest that the exclusive reaction ${(e,e}^{\prime }p)$ with high precision data may provide an even tighter constraint on possible medium modifications of the proton form factors.

The ${}^{22}\mathrm{Ne}(\alpha ,n)$ reaction is the main neutron source for neutron capture nucleosynthesis $(s$ process) in massive stars and plays also a significant role for the s process in thermally pulsing asymptotic giant branch stars. In these scenarios, ${}^{22}\mathrm{Ne}$ is produced by the reaction sequence ${}^{14}\mathrm{N}(\alpha ,\gamma {)}^{18}\mathrm{F}({\beta }^{+}{)}^{18}\mathrm{O}(\alpha ,\gamma {)}^{22}\mathrm{Ne}.$ While the first reaction is well understood, α capture on ${}^{18}\mathrm{O}$ was affected by considerable uncertainties. At the temperatures of stellar He burning, the reaction rate is determined by two resonances at α energies of 470 and 566 keV. Since these resonances were not yet successfully measured, the rates had to be based on estimated resonance strengths. In the present work, the first direct measurement of the partial strengths of these extremely weak low-energy resonances is reported. The use of a high-efficiency segmented Ge detector in coincidence with bismuth germanate oxide counters covering a large solid angle led to a significantly improved experimental sensitivity, thus allowing for the clear identification of specific γ transitions. As a result, resonance strengths of 0.71±0.17 μeV and 0.48±0.16 μeV could be obtained for the 566- and 470-keV resonances, respectively. When compared to the previously reported upper limits of ⩽1.7 μeV, these results provide a reliable basis for the determination of the reaction rate during stellar He burning. Accordingly, these data reduce the uncertainties in the s process neutron balance.

We use recent results of β-delayed neutron emission from ${}^{14}\mathrm{Be}$ to estimate the configuration of the ground state of ${}^{13}\mathrm{B}.$ We also discuss consequences for ${}^{14}\mathrm{Be}$ and ${}^{14}\mathrm{B}.$

We have performed time dependent Hartree-Fock calculations on the nonlinear response of nuclei. We have shown that quadrupole (and dipole) motion produces monopole (and quadrupole) oscillations in all atomic nuclei. We have shown that these findings can be interpreted as a large coupling between one and two phonon states leading to strong anharmonicities.

We show that a recently proposed derivation of Bose-Einstein correlations (BEC) by means of a specific version of thermal quantum field theory, supplemented by operator-field evolution of the Langevin type, allows for a deeper understanding of the possible coherent behavior of the emitting source and a clear identification of the origin of the observed shape of the BEC function $C_2\mathrm{}\left(Q\right).$ Previous conjectures in this matter obtained by other approaches are confirmed and have received complementary explanation.

Projectilelike fragments (PLF, $15<~Z<~46)$ formed in peripheral and midperipheral collisions of ${}^{114}\mathrm{Cd}$ projectiles with ${}^{92}\mathrm{Mo}$ nuclei at $E/A=50\mathrm{}\mathrm{MeV}$ have been detected at very forward angles, $2.1°<~{\theta }_{\mathrm{lab}}<~4.2°.$ Calorimetric analysis of the charged particles observed in coincidence with the PLF reveals that the excitation of the primary PLF is strongly related to its velocity damping. Furthermore, for a given $V_{\mathrm{PLF}*},$ its excitation is not related to its size, $Z_{\mathrm{PLF}*}.$ For the largest velocity damping, the excitation energy attained is large, approximately commensurate with a system at the limiting temperature.

The properties of negative-parity states in ${}^{114}\mathrm{Cd}$ have been studied with the ${(n,n}^{\prime }\gamma )$ reaction. $\gamma$-ray angular distributions and excitation functions have been used to characterize the decays of these excited levels, and level lifetimes have been obtained with the Doppler-shift attenuation method. A set of five closely spaced, negative-parity states has been identified as the complete quadrupole-octupole quintuplet. These excited states and the observed transitions from these levels are compared to calculations performed in the framework of the $\mathrm{spdf}$ interacting boson model.

$\gamma$ decays from high-spin states in the $N=Z-1$ nucleus ${}_{27}^{53}{\mathrm{Co}}_{26}$ have been identified for the first time. Level energies and Coulomb energy differences between these states and their analogs in its mirror nucleus ${}^{53}\mathrm{Fe}$ have been compared with large-scale $\mathrm{pf}$ shell-model calculations, which offer excellent agreement. New information has been obtained on two-proton Coulomb matrix elements needed in the interpretation. These have been extracted from the data via a number of methods and are shown to exhibit an anomalous behavior for the $J=2\mathrm{}$ coupling.

A compact approach based on the folding model is suggested for the determination of the isoscalar and isovector transition strengths of the low-lying $(\Delta S=\Delta T=0)$ excitations induced by inelastic proton scattering measured with exotic beams. Our analysis of the recently measured inelastic ${}^{18,20}\mathrm{O}+p$ scattering data at $E_{\mathrm{lab}}=30\mathrm{}$ and 43 MeV/nucleon has given for the first time an accurate estimate of the isoscalar ${\beta }_0$ and isovector ${\beta }_1$ deformation parameters [which cannot be determined from the ${(p,p}^{\prime })$ data alone by standard methods] for $2_1^{+}$ and $3_1^{-}$ excited states in ${}^{18,20}\mathrm{O}.$ Quite strong isovector mixing was found in the $2_1^{+}$ inelastic ${}^{20}\mathrm{O}+p$ scattering channel, where the strength of the isovector form factor $F_1$ (prototype of the Lane potential) corresponds to a ${\beta }_1$ value almost three times larger than ${\beta }_0$ and a ratio of nuclear transition matrix elements, $M_n{/M}_p\simeq \mathrm{4.2.}$

The large set of accurate data on differential cross section and analyzing power from the CERN LEAR experiment on $\overline{p}\overrightarrow{p}{\pi }^{-}{\pi }^{+},$ in the range from 360 to $1550\mathrm{MeV}/c,$ is well reproduced within a distorted wave approximation approach. The initial $\overline{p}p$ scattering wave functions originate from a recent $\overline{N}N$ model. The transition operator is obtained from a combination of the ${}^3{P}_0$ and ${}^3{S}_1$ quark-antiquark annihilation mechanisms. A good fit to the data, in particular, the reproduction of the double-dip structure observed in the analyzing powers, requires quark wave functions for proton, antiproton, and pions with radii slightly larger than the respective measured charge radii. This corresponds to an increase in the range of the annihilation mechanisms, and consequently, the amplitudes for total angular momentum $J=2\mathrm{}$ and higher are much larger than in previous approaches. The final-state $\pi \pi$ wave functions, parametrized in terms of $\pi \pi$ phase shifts and inelasticities, are also a very important ingredient for the fine tuning of the fit to the observables.

By introducing a density-dependent contact term, M3Y-type interactions applicable to the Hartree-Fock calculations are developed. In order to view basic characters of the interactions, we carry out calculations on the uniform nuclear matter as well as on several doubly magic nuclei. It is shown that a parameter set called M3Y-P2 describes various properties similarly well to the Skyrme SLy5 and/or the Gogny D1S interactions. A remarkable difference from the SLy5 and D1S interactions is found in the spin-isospin properties in the nuclear matter, to which the one-pion-exchange potential gives a significant contribution. Affecting the single-particle energies, this difference may play a certain role in the new magic numbers in unstable nuclei.

We carry out shell model calculations to study electromagnetic moments and electric dipole transitions of C isotopes. We point out the configuration dependence of the quadrupole and magnetic moments of the odd C isotopes, which will be useful to find out the deformations and the spin parities of the ground states of these nuclei. We also study the electric dipole states of C isotopes, focusing on the interplay between low energy pigmy strength and giant dipole resonances. As far as the energies of the resonances are concerned, reasonable agreement is obtained with available experimental data for the photoreaction cross sections in ${}^{12}\mathrm{C},$ ${}^{13}\mathrm{C},$ and ${}^{14}\mathrm{C},$ both in the low energy region below $ħ\omega =14\mathrm{}\mathrm{MeV}$ and in the high energy giant resonance region (14 MeV $<ħ\omega <~30\mathrm{MeV}).\mathrm{}$ The calculated transition strength below the giant dipole resonance $(ħ\omega <~14\mathrm{MeV})$ in C isotopes heavier than ${}^{15}\mathrm{C}$ is found to exhaust about $12–16\%$ of the classical Thomas-Reiche-Kuhn sum rule value and $50–80\%$ of the cluster sum rule value.

The modified Hartree-Fock-Bogoliubov (MHFB) theory at finite temperature is derived, which conserves the unitarity relation of the particle-density matrix. This is achieved by constructing a modified-quasiparticle-density matrix, where the fluctuation of the quasiparticle number is microscopically built in. This matrix can be directly obtained from the usual quasiparticle-density matrix by applying the secondary Bogoliubov transformation, which includes the quasiparticle-occupation number. It is shown that, in the limit of constant pairing parameter, the MHFB theory yields the previously obtained modified BCS (MBCS) equations. It is also proved that the modified quasiparticle-random-phase approximation, which is based on the MBCS quasiparticle excitations, conserves the Ikeda sum rule. The numerical calculations of the pairing gap, heat capacity, level density, and level-density parameter within the MBCS theory are carried out for ${}^{120}\mathrm{Sn}.$ The results show that the superfluid-normal phase transition is completely washed out. The applicability of the MBCS up to a temperature as high as $T\sim 5\mathrm{MeV}$ is analyzed in detail.

The structures of the ground and excited states of ${}^{12}\mathrm{Be}$ were studied with antisymmetrized molecular dynamics. The ground state was found to be a state with a developed $2\alpha$ core with two neutrons occupying the intruder orbits. The energy levels of the newly measured spin-assigned states were described well, except for the $1_1^{-}$ state. The calculations indicated that many exotic cluster structures appear in the low-energy region. The widths concerning $\alpha$ and ${}^6\mathrm{He}$ decays were discussed by using reduced width amplitudes.