We investigate the role of meson exchange currents within an extended random phase approximation framework for inclusive quasielastic electron scattering on nuclei. The scheme is fully antisymmetric. Interference terms between one-body and two-body external excitation operators are considered and discussed. We calculate the transverse response function for nonrelativistic nuclear matter at several momentum transfers. The results show that the inclusion of these interference terms is relevant only in the dip region, while they are of minor importance for the quasielastic peak.

The decay of the neutron-rich nucleus ${}^{110}\mathrm{Tc}$ has been investigated using β-γ and γ-γ coincidences. The on-line mass separated source is produced by using the ion-guide technique from fission products. An extended level scheme of ${}^{110}\mathrm{Ru}$ has been constructed, including 20 new excited states and 36 new γ transitions. The β feedings, $\log \mathrm{ft}$ values, and $B\left(E2\mathrm{}\right)\mathrm{}$ ratios were extracted. A spin and parity of $0^{+}$ is suggested for a level at 1137 keV in ${}^{110}\mathrm{Ru},$ and the spin and parity of the previously identified $2_3^{+}$ state was confirmed. Level systematics of neutron-rich even-even Ru isotopes shows that the maximum deformation is at $A=112\mathrm{}$ $\mathrm{}(N=68\mathrm{}),$ two neutrons more than the middle of the $N=50\mathrm{}–82$ neutron shell. The experimental results are compared with theoretical values calculated by different nuclear models.

γ-ray decays depopulating isomeric states have been observed in a number of very neutron deficient nuclei around $A\sim 80$ following the projectile fragmentation of a ${}^{92}\mathrm{Mo}$ primary beam. Previously unobserved decays have been identified in the $N=Z+2\mathrm{}$ nuclei ${}_{39}^{80}\mathrm{Y}$ and ${}_{41}^{84}\mathrm{Nb}$ and the $N=Z$ nucleus, ${}_{43}^{86}\mathrm{Tc},$ making the latter the heaviest $N=Z$ nucleus to date in which a discrete γ-ray transition has been assigned. The lifetime of the previously reported $I^{\pi }={\frac{9}{2}}^{+}$ isomeric state in ${}^{73}\mathrm{Kr}$ has also been measured and a clearer picture of its decay properties has been deduced. Isomeric ratios have been measured and have been interpreted in terms of the yrast or nonyrast nature of the isomeric state.

The yrast sequence in ${}^{183}\mathrm{Tl}$ has been studied for the first time in recoil-mass selected γ-ray spectroscopic measurements. A rotational-like cascade of seven transitions is established down to the band head with probable spin and parity ${(13/2\mathrm{}}^{+}).\mathrm{}$ Unlike in the adjacent odd-mass Tl nuclei, prompt γ decay from the yrast band to a lower lying weakly deformed (oblate) structure is not observed. These features are consistent with the predicted drop of the prolate band head in ${}^{183}\mathrm{Tl}$ compared to ${}^{185}\mathrm{Tl}.$ The implications for the prolate energy minimum in odd-mass Tl nuclei at the neutron $i_{13/2}$ midshell $\mathrm{}(N=103\mathrm{})\mathrm{}$ are discussed.

Neutrino reaction cross sections $({\nu }_{\mu },{\mu }^{-}),$ $\left({\nu }_e{,e}^{-}\right)$ and $\mu$-capture and photoabsorption rates on ${}^{12}\mathrm{C}$ are computed within a large-basis shell-model framework, which included excitations up to $4ħ\omega .$ When ground-state correlations are included with an open p shell the predictions of the calculations are in reasonable agreement with most of the experimental results for these reactions. Woods-Saxon radial wave functions are used, with their asymptotic forms matched to the experimental separation energies for bound states, and matched to a binding energy of 0.01 MeV for unbound states. We obtain, for the neutrino-absorption inclusive cross sections (but excluding the ${}^{12}\mathrm{N}\mathrm{}$ ground-state contribution) $\overline{\sigma }=13.2\mathrm{}\times {10}^{-40}\hspace{0.5em}{\mathrm{cm}}^2$ for the $({\nu }_{\mu },{\mu }^{-})$ decay-in-flight flux in agreement with the LSND datum of $(11.7\mathrm{}\pm 1.8)\times {10}^{-40}\hspace{0.5em}{\mathrm{cm}}^2$ and $\overline{\sigma }=4.1\mathrm{}\times {10}^{-42}\hspace{0.5em}{\mathrm{cm}}^2$ for the $\left({\nu }_e{,e}^{-}\right)$ decay-at-rest flux, less than the experimental result of $(5.4\mathrm{}\pm 0.8)\times {10}^{-42}\hspace{0.5em}{\mathrm{cm}}^2.$

Within the formalism of Glauber multiple scattering theory, high-energy elastic collisions between light and medium weight nuclei $(A,B>~4)$ have been investigated by invoking an exact center-of-mass correlation function in each order of the complete expansion of the phase-shift function. The calculated angular distributions $(\mathrm{n}\mathrm{u}\mathrm{c}\mathrm{l}\mathrm{e}\mathrm{a}\mathrm{r}+\mathrm{C}\mathrm{o}\mathrm{u}\mathrm{l}\mathrm{o}\mathrm{m}\mathrm{b}),$ using the developed formulas, show better agreement with the scattering data.

We confront for the first time the widely-held belief that combined event-by-event information from quark gluon plasma signals can reduce the ambiguity of the individual signals. We illustrate specifically how the measured antiproton yield combined with the information from pion-pion HBT correlations can be used to identify novel event classes.

It is shown that the spectrum of the asymmetric rotor can be realized quantum mechanically in terms of a system of interacting bosons. This is achieved in the SU(3) limit of the interacting boson model by considering higher-order interactions between the bosons. The spectrum corresponds to that of a rigid asymmetric rotor in the limit of infinite boson number.

The rainbow truncation of the quark Dyson-Schwinger equation is combined with the ladder Bethe-Salpeter equation for the dressed quark-photon vertex to study the low-momentum behavior of the pion electromagnetic form factor. With model gluon parameters previously fixed by the pion mass and decay constant, the pion charge radius $r_{\pi }$ is found to be in good agreement with the data. In this work, about half of $r_{\pi }^2$ is seen to be attributable to the presence of the $\rho$ pole in the solution of the ladder Bethe-Salpeter equation.

The nucleon density distributions and the thickness of pure neutron matter in Ca isotopes were systematically studied using the Skyrme-Hartree-Fock (SHF) model from the $\beta$-stability line to the neutron drip line. Pure neutron matter, related to the neutron skin or halo, was shown to depend not only on the Fermi levels of the neutrons but also on the orbital angular momentum of the valence neutrons. New definitions for the thickness of pure neutron matter are proposed.

Excited states in ${}^{137}\mathrm{Te},$ populated in spontaneous fission of ${}^{248}\mathrm{Cm},$ were studied by means of prompt-$\gamma$ spectroscopy, using the EUROGAM2 multidetector array. This is the first observation of excited states in ${}^{137}\mathrm{Te}.$ The yrast excitations of ${}^{137}\mathrm{Te}$ are due to the three valence neutrons, occupying the $\nu f_{7/2}$ and $\nu h_{9/2}$ orbitals, similarly as observed in its heavier $N=85\mathrm{}$ isotones. Systematic comparison of excited levels in the $N=85\mathrm{}$ isotones shows inconsistencies in spin and parity assignments in ${}^{139}\mathrm{Xe}$ and ${}^{141}\mathrm{Ba}$ nuclei. The new data for ${}^{137}\mathrm{Te}$ do not confirm earlier suggestions that octupole correlations increase in the $N=85\mathrm{}$ isotones, close to the $Z=50\mathrm{}$ closed shell.

The nucleus ${}^{166}\mathrm{Ho}$ was studied with thermal and average resonance neutron capture and with $\mathrm{}(d,p)\mathrm{}$ and ${(d,}^3\mathrm{He})$ reactions. We have devoted a large effort to the measurements of $\gamma \gamma$-coincidence spectra in the broad energy interval 50–6243 keV. From these data and those of previous studies, the level scheme has been developed containing levels grouped into 23 rotational bands below 1 MeV. Of these, six bands are new and several others, known previously, have been modified and expanded based upon our experimental data. In all, 32 new levels have been identified. Of particular note has been the identification of two rotational bands whose underlying structure consists of $\gamma$-vibrational states built upon the two lowest energy quasiparticle states in ${}^{166}\mathrm{Ho}.$ Two new Gallagher-Moszkowski matrix elements were determined: $E_{\mathrm{GM}}{(p7/2\mathrm{}}^{-}\left[523\right]\pm {n5/2\mathrm{}}^{-}\left[523\right])=-108.5$ keV and $E_{\mathrm{GM}}\{{(p7/2\mathrm{}}^{-}\left[523\right]\pm {n7/2\mathrm{}}^{+}\left[633\right])\mp Q_{22}\}=+138.2\mathrm{}$ keV. The resultant level scheme is in good agreement with semiempirical and quasiparticle phonon models where residual interactions have been taken into account. Suggestions are given for further experimentation on ${}^{166}\mathrm{Ho}$ level structure using existing technology.

It is shown that the observables in ordinary muon capture depend very sensitively on the ratios of nuclear matrix elements. This is demonstrated for the case of extracting $g_P{/g}_A$ from $\gamma \nu$-correlation experiments on ${}^{28}\mathrm{Si}$ and from the ratio of capture rates from hyperfine states in ${}^{11}\mathrm{B}$ and ${}^{23}\mathrm{Na}.$

Superdeformed configurations in ${}^{32}\mathrm{S},$ and in neighboring nuclei ${}^{33}\mathrm{S},$ ${}^{31}\mathrm{S},$ ${}^{33}\mathrm{Cl},$ and ${}^{31}\mathrm{P},$ are determined within the Hartree-Fock approach with the Skyrme interaction. Energies, angular momenta, quadrupole moments, particle-emission Q values, and relative alignments and quadrupole moments are calculated for a number of superdeformed rotational bands in these nuclei. A new mechanism implying an existence of signature-separated rotational bands, distinct from the well-known signature-split bands, is discussed and associated with the time-odd channels of effective interactions.

The isotopes ${}^{255}\mathrm{Md}$ and ${}^{256}\mathrm{Md}$ were produced by the irradiation of ${}^{253}\mathrm{Es}$ with 35–45 MeV $\alpha$ particles by $(\alpha ,n)$ and $(\alpha ,2n)$ reactions and were removed from the target by a helium jet system. $\alpha ,$ $\gamma ,$ and $\alpha$-$\gamma$ coincidence spectra were measured with Si and Ge(Li) detectors. From the EC decays of ${}^{255}\mathrm{Md}$ and ${}^{256}\mathrm{Md},$ levels in ${}^{255}\mathrm{Fm}$ and ${}^{256}\mathrm{Fm}$ were deduced. Favored $\alpha$ decay of ${}^{255}\mathrm{Md}$ was found to populate the ${7/2}^{-}\left[514\right]$ single-particle state in ${}^{251}\mathrm{Es},$ thus establishing the ${7/2}^{-}\left[514\right]$ as the ${}^{255}\mathrm{Md}$ ground state. Several $\gamma$ rays were observed in the ${}^{256}\mathrm{Md}$ $\alpha$-$\gamma$ coincidence spectrum. ${}^{256}\mathrm{Fm}$ is the heaviest nucleus in which excited intrinsic states have been identified.

We study the ground state properties of doubly closed shell nuclei ${}^{16}\mathrm{O}$ and ${}^{40}\mathrm{Ca}$ in the framework of correlated basis function theory using state dependent correlations, with central and tensor components. The realistic Argonne $v_{14}$ and $v_8^{\prime }$ two-nucleon potentials and three-nucleon potentials of the Urbana class have been adopted. By means of the Fermi hypernetted chain integral equations, in conjunction with the single operator chain approximation, we evaluate the ground state energy, one- and two-body densities and electromagnetic and spin static responses for both nuclei. In ${}^{16}\mathrm{O}$ we compare our results with the available Monte Carlo and coupled cluster ones and find a satisfying agreement. As in the nuclear matter case with similar interactions and wave functions, the nuclei result underbound by 2–3 MeV/nucleon.

The value of an isomeric ratio (IR) in $N=81\mathrm{}$ isotones ${(}^{137}\mathrm{Ba},$ ${}^{139}\mathrm{Ce},$ ${}^{141}\mathrm{Nd},$ and ${}^{143}\mathrm{Sm})$ is studied by means of the $(\gamma ,n)$ reaction. This quantity measures a probability to populate the isomeric state in respect to the ground state population. In $(\gamma ,n)$ reactions, the giant dipole resonance (GDR) is excited and after its decay by a neutron emission, the nucleus has an excitation energy of a few MeV. The forthcoming $\gamma$ decay by direct or cascade transitions deexcites the nucleus into an isomeric or ground state. It has been observed experimentally that the IR for ${}^{137}\mathrm{Ba}$ and ${}^{139}\mathrm{Ce}$ equals about 0.13 while in two heavier isotones it is even less than half the size. To explain this effect, the structure of the excited states in the energy region up to 6.5 MeV has been calculated within the quasiparticle phonon model. Many states are found connected to the ground and isomeric states by $E1,$ $E2,$ and $M1\mathrm{}$ transitions. The single-particle component of the wave function is responsible for the large values of the transitions. The calculated value of the isomeric ratio is in very good agreement with the experimental data for all isotones. A slightly different value of maximum energy with which the nuclei rest after neutron decay of the GDR is responsible for the reported effect of the A dependence of the IR.

We investigate the use of proton-nucleus elastic scattering experiments using secondary beams of ${}^6\mathrm{He}$ and ${}^8\mathrm{He}$ to determine the physical structure of these nuclei. The sensitivity of these experiments to nuclear structure is examined by using four different nuclear structure models with different spatial features using a full-folding optical potential model. The results show that elastic scattering at intermediate energies $(<\mathrm{}100\mathrm{}$ MeV per nucleon) is not a good constraint to be used to determine features of structure. Therefore researchers should look elsewhere to put constraints on the ground state wave function of the ${}^6\mathrm{He}$ and ${}^8\mathrm{He}$ nuclei.

The strong coupling constants $g_{K\Lambda N}$ and $g_{K\Sigma N}$ for the structure ${\sigma }_{\mu \nu }{\gamma }_5$ are calculated within light-cone QCD sum rules. A comparison of our results on these couplings with predictions from traditional QCD sum rules is presented.

We investigate the structure of the neutron rich nucleus ${}^{19}\mathrm{C}$ through studies of its breakup in the Coulomb field of target nuclei. The breakup amplitude is calculated within an adiabatic treatment of the projectile excitation, which allows the use of the realistic wave functions for the relative motion between the fragments in the ground state of the projectile. The angular distribution of the center of mass of ${}^{19}\mathrm{C},$ longitudinal momentum distribution of ${}^{18}\mathrm{C},$ and relative energy spectrum of the fragments (neutron-${}^{18}\mathrm{C})$ following the breakup of ${}^{19}\mathrm{C}$ on heavy targets at beam energies below 100 MeV/nucleon have been computed using different configurations for the ground state wave function of ${}^{19}\mathrm{C}.$ In all cases, the data seem to favor a ${}^{18}\mathrm{C}{(0\mathrm{}}^{+})\otimes {1s}_{1/2}$ configuration for the ground state of ${}^{19}\mathrm{C},$ with a one-neutron separation energy of 0.53 MeV.