We analyze the role of different equations of state and momentum dependent interactions in fragmentation. Heavy ion collisions are simulated using a quantum molecular dynamics model and fragments are constructed with the minimum spanning tree method. A detailed study is carried out for $\mathrm{X}\mathrm{e}+\mathrm{S}\mathrm{n}$ reactions at incident energies $E=100\mathrm{}$ and 400 MeV/nucleon and over a wide range of impact parameters. Our analysis indicates that the light mass fragments in central collisions are sensitive towards different static equations of state whereas the heavy fragments are insensitive towards different static equations of state. The results with momentum dependent interactions are quite different. Now, the heavy fragments are also sensitive towards different equations of state. The momentum dependence of the equation of state is able to break the spectator matter into a large number of fragments at peripheral collisions whereas a simple static equation of state fails to produce any fragments. As a result, the properties of fragments (such as transverse flow, rapidity distribution, etc.) are also affected by the momentum dependence of the interaction.

We propose a new method for studying properties of excited states of hadrons based on electroproduction of baryon resonances from the deuteron. The measurement is capable of distinguishing between competing models of a specific resonance by exploiting the sensitivity of the cross section to the radius and compositeness of the resonances. These studies are made feasible, in part, by the strong hadronic reinteraction of the resonance with the spectator neutron in specific kinematic situations. We establish our claims by studying the reaction $d\left[{e,e}^{\prime }{S}_{11}\mathrm{}\right(1535\left)\mathrm{}\right]N$ for $Q^2>~1\hspace{0.5em}{\mathrm{GeV}}^2,$ where the $S_{11}$ suffers a prominent final state interaction. Sensitivity to the model is established by comparing numerical results obtained from a constituent quark model and an effective chiral Lagrangian model of the $S_{11}.$

We introduce the chemical potential in a system of two-flavored massless fermions in a chiral bag, with an external Skyrmion, by imposing boundary conditions in the Euclidean time direction. We express the fermionic mean number in terms of a functional trace involving the Green function of the boundary value problem, which is studied analytically. Numerical evaluations for the fermionic number are presented.

The recently available $\pi N$ elastic, phase-shift analysis SP98, and interior dispersion relations are used to obtain the invariant amplitudes in the subthreshold crescent where they can be compared directly to the predictions of chiral theories.

We reexamine the recent instanton motivated studies of Alford, Rajagopal, and Wilczek, and Berges and Rajagopal in the framework of the standard SU(2) Nambu–Jona-Lasinio (NJL) model. The chiral phase diagram is calculated in the temperature-density plane, and the pressure is evaluated as the function of the quark density. Obtaining simple approximate relations describing the T-μ and $T-p_F$ phase transition lines, we find that the results of the instanton based model and that of the NJL model are identical. The diquark transition line is also given.

We report yields for 38 γ-ray lines and 29 $({\mu }^{-},\nu )$ transitions following negative muon capture on ${}^{24}\mathrm{Mg},$ ${}^{28}\mathrm{Si},$ ${}^{31}\mathrm{P},$ and ${}^{32}\mathrm{S}.$ Our results substantially increase the world data set for partial $({\mu }^{-},\nu )$ transitions on $1s-0d$ shell nuclei. They also resolve a number of inconsistencies between previously published γ-ray yields and accepted γ-decay branching ratios. We compare the measured capture rates for the allowed Gamow-Teller (GT) transitions (supplemented with earlier ${}^{23}\mathrm{Na}$ data) with a shell model calculation using the full $1s-0d$ space and universal SD interaction. We find a “best fit” value of the effective weak axial coupling of $g_a=-{0.91}_{-0.17}^{+0.15\mathrm{}},$ fair agreement for the per-target summed GT capture rates, but poor agreement for the individual GT capture rates. By replacing the shell model $\sigma {\tau }^{\pm }$ matrix element values with experimentally determined $\sigma {\tau }^{\pm }$ matrix element values, improved predictions for the individual GT capture rates are obtained. Last, we comment on recent determinations of the weak coupling $g_p$ via muon capture on $1s-0d$ shell nuclei.

The solar neutrino capture rate measured by the Russian-American Gallium Experiment (SAGE) on metallic gallium during the period January 1990 through December 1997 is ${67.2}_{-7.0-3.0}^{+7.2+3.5\mathrm{}}$ SNU, where the uncertainties are statistical and systematic, respectively. This represents only about half of the predicted standard solar model rate of 129 SNU. All the experimental procedures, including extraction of germanium from gallium, counting of ${}^{71}\mathrm{Ge},$ and data analysis, are discussed in detail.

The critical behaviors of the quark-hadron phase transition are explored by use of the Ising model adapted for hadron production. Various measures involving the fluctuations of the produced hadrons in bins of various sizes are examined with the aim of quantifying the clustering properties that are universal features of all critical phenomena. Some of the measures involve wavelet analysis. Two of the measures are found to exhibit the canonical power-law behavior near the critical temperature. The effect of final-state randomization is studied by requiring the produced particles to take random walks in the transverse plane. It is demonstrated that for the measures considered the dependence on the randomization process is weak. Since temperature is not a directly measurable variable, the average hadronic density of a portion of each event is used as the control variable that is measurable. The event-to-event fluctuations are taken into account in the study of the dependence of the chosen measures on that control variable. Phenomenologically verifiable critical behaviors are found and are proposed for use as a signature of quark-hadron phase transition in relativistic heavy-ion collisions.

The odd-even differences of nuclear masses are strongly influenced by mean-field and odd-nucleon blocking effects. When such effects are taken into account, the determination of the pairing interaction strength needs to be modified, resulting in larger pairing gaps. This method leads to an improved description for both moments of inertia and backbending frequencies of rotational bands, with no additional parameters.

We investigate the observable effects of off-shell propagation of nucleons in heavy-ion collisions at SIS energies. Within a semiclassical Boltzmann-Uehling-Uhlenback transport model we find a strong enhancement of subthreshold particle production when off-shell nucleons are propagated.

The differential cross section for ${}^2\mathrm{H}(\gamma ,d){\pi }^0$ has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions.

A quantal Hamiltonian ${\hat{\mathcal{H}}}_{\mathrm{coll}}$ expressed in terms of the five collective quadrupole coordinates is built for eight nuclei ${(}^{190,192,194}$Hg, ${}^{192,194,196}$Pb, and ${}^{196,198}$Po) which display secondary minima at large elongation in their potential energy surface. These surfaces as well as the tensor of inertia entering ${\hat{\mathcal{H}}}_{\mathrm{coll}}$ are deduced from constrained Hartree-Fock-Bogoliubov calculations based on Gogny force. A two-center basis method employed to solve ${\hat{\mathcal{H}}}_{\mathrm{coll}}$ is presented. The stability of predicted collective spectra is discussed. Yrast and vibrational $\pi =+$ superdeformed (SD) bands are predicted together with collective bands at normal deformation (ND). The predicted yrast SD bands at low spin display properties which compare favorably with experimental information. Quite good agreement is in particular obtained for the isomeric energies of nuclei for which the link between SD and ND levels is experimentally known. Among the excited SD bands which are here predicted, those built on top of $\beta$ vibrations are lower in energy. Only for the ${}^{196,198}$Po isotopes are these excitation energies falling in the low energy range $E\sim$0.8–1.0 MeV. These properties should favor an experimental discovery of $\beta$-vibrational SD bands in the $A\sim$190 mass region.

A mean lifetime measurement using the Doppler shift attenuation method has been performed at GASP in order to measure the quadrupole moment of the yrast superdeformed band of ${}^{144}\mathrm{Gd}$. The extracted intrinsic quadrupole moment above the backbending, $Q_0{=13.7\mathrm{}}_{-0.9}^{+1.1\mathrm{}}\hspace{0.5em}e$ b, is in nice agreement with cranked shell model predictions. To fit the data properly below the backbending a smaller $Q_0$ value is required ${(11.6\mathrm{}}_{-1.0}^{+1.4\mathrm{}})e$ b. This is consistent with the predicted lower deformation in the second well for the configuration without high-$N$ $(\pi N=6\mathrm{}$ and $\nu N=7)$ intruder orbitals occupied.

A many-body expansion for the computation of the charge form factor in the center-of-mass system is proposed. For convergence testing purposes, we apply our formalism to the case of the harmonic oscillator shell model, where an exact solution exists. We also work out the details of the calculation involving realistic nuclear wave functions. Results obtained for the Argonne $v$18 two-nucleon and Urbana-IX three-nucleon interactions are reported. No corrections due to the meson-exchange charge density are taken into account.

The ${}^{143}\mathrm{Tb}$ nucleus has been studied with the ${}^{92}\mathrm{Mo}$ (${}^{54}\mathrm{Fe},$ $3p\gamma$) reaction at 240-MeV incident energy, extending the systematics of odd-$A,$ $N=78\mathrm{}$ isotones to higher $Z.\mathrm{}$ For the yrast band, excited states up to a spin of ${59/2}^{-}$ have been observed. The first allowed backbend occurs at a rotational frequency of $ħ\omega =0.38\mathrm{}\mathrm{MeV}.$ Three- and five-quasiparticle structures were identified, similar to those seen in lower mass $N=78\mathrm{}$ isotones. Two of these structures have characteristics typical of mixed proton-neutron oblate configurations with one pair of aligned $h_{11/2}$ neutrons. In addition, two bands consisting of stretched $E2\mathrm{}$ transitions have been observed with no known analogous structures in neighboring nuclei. The results are discussed in terms of the cranking model.

The energy spectra and electromagnetic transition probabilities of the negative-parity yrast states in odd-$A$ Lu isotopes $\mathrm{}(Z=71\mathrm{})\mathrm{}$ are investigated systematically using the particle-rotor model and are compared with experimental data before and after the band crossing. It is noted that the moment of inertia of the core after the band crossing is as much a smooth function of the total angular momentum $I,$ as that before the band crossing and can be described by the $\mathrm{ab}$ formula. Appreciably different are the triaxial deformations before $\left(\sim -20°\right)$ and after $(\sim +10\mathrm{}°)$ the band crossing for ${}^{161,163,165}\mathrm{Lu},$ while they are more or less similar $\left(\sim -10°\right)$ for ${}^{167}\mathrm{Lu}$ determined from the calculation.

We develop a shell-model Monte Carlo method to calculate densities of states with varying exciton (particle-hole) number. We then apply this method to the doubly closed-shell nucleus ${}^{40}\mathrm{Ca}$ in a full $0s-1d-0f-1p$ shell-model space and compare our results to those found using approximate analytic expressions for the partial densities. We find that the effective one-body level density is reduced by approximately 22% when a residual two-body interaction is included in the shell-model calculation.

A radioactive beam of ${}^{69}\mathrm{Ni}$ was produced by the fragmentation of a 70 MeV/nucleon ${}^{76}\mathrm{Ge}$ beam in a Be target. $\beta$-delayed $\gamma$-ray studies were performed using two thin plastic scintillators and two large-volume Ge detectors following implantation of the ${}^{69}\mathrm{Ni}$ nuclei into a foil of a collection wheel apparatus. A 1296-keV $\gamma$-ray transition with a half-life of 3.4(7) s was identified and has been attributed to the decay of the $\nu p_{1/2}^{-1}$ isomeric state in ${}^{69}\mathrm{Ni}.$ The relative population of the low-spin $J^{\pi }{=1/2\mathrm{}}^{-}$ isomer to the known high-spin $J^{\pi }{=(17/2\mathrm{}}^{-})$ isomer was determined to be 6:1 for the production of ${}^{69}\mathrm{Ni}$ via fragmentation of ${}^{76}\mathrm{Ge},$ based on an upper limit of 36% extracted for the ${}^{69}{\mathrm{Ni}}^{m1\mathrm{}}$ $\beta$-decay branch to the ${3/2}^{-}$ ground state of ${}^{69}\mathrm{Cu}.$ The half-life and branching of the ${}^{69}{\mathrm{Ni}}^{m1\mathrm{}}$ $\beta$ decay is discussed in light of possible two particle–two hole excitations in the low-energy structure of ${}^{69}\mathrm{Cu}.$

The damping of hot giant dipole resonances is investigated. The contribution of surface scattering is compared with the contribution from interparticle collisions. A unified response function is presented which includes surface damping as well as collisional damping. The surface damping enters the response via the Lyapunov exponent and the collisional damping via the relaxation time. The former is calculated for different shape deformations of quadrupole and octupole type. The surface as well as the collisional contribution each reproduce almost the experimental value, and therefore we propose a proper weighting between both contributions related to their relative occurrence due to collision frequencies between particles and of particles with the surface. We find that for low and high temperatures the collisional contribution dominates whereas the surface damping is dominant around the temperatures $\sqrt{3}/2\mathrm{}\pi$ of the centroid energy.

Fission fragment cross sections and angular anisotropies have been measured to high accuracy for the ${}^{19}{\mathrm{F}+}^{208}\mathrm{Pb}$ reaction, together with evaporation residue cross sections, at bombarding energies from below the fusion barrier to 1.75 times the barrier energy. These data allow reliable calculations of the partial waves contributing to fission. Extensive statistical model calculations of the anisotropies are presented, including the effects of different fission transient delay times. The anisotropies at the highest bombarding energies can only be reproduced assuming that the fission barrier no longer controls the fission process when its height is less than the nuclear temperature.