The $10.5\text{‐}\text{day}$ isomer in ${}^{193}\mathrm{Ir}$ decays by a single $80.2\text{‐}\mathrm{keV}$ $M4$ transition directly to the ground state of that nucleus. We have measured the total intensity of $K$ x rays relative to $80.2\text{‐}\mathrm{keV}$ $\gamma$ rays for this transition to be 98.7(6). With the $K$-shell fluorescent yield for iridium taken to be 0.958(4), this result yields ${\alpha }_K=103.0\left(8\right)$ for the $K$-shell internal conversion coefficient (ICC). The calculated ${\alpha }_K$ for this transition is particularly sensitive to the treatment of the hole that is created by conversion in the atomic $K$ shell. Recent ICC tables, which ignore the hole, yield ${\alpha }_K=92.0$. We demonstrate that calculations incorporating the hole produce values between 99.6 and 103.3 depending on the approximation used. Our result strongly supports the need to include the hole.

Calculations based on the sudden approximation have been performed to describe high-energy single-nucleon removal reactions. Within this approach, which takes as its starting point the formalism developed to describe the breakup of well-developed single-neutron halo systems, the nucleon-removal cross section and the full three-dimensional momentum distributions of the core fragments, including absorption, diffraction, Coulomb, and nuclear-Coulomb interference amplitudes, have been computed. The Coulomb, breakup has been treated to all orders for the dipole interaction. The results are compared here to experimental data for a range of light, neutron-rich $psd$-shell nuclei taken at beam energies of $43–68\mathrm{MeV}∕\text{nucleon}$. Good agreement is found for the inclusive cross sections and both the longitudinal and transverse momentum distributions. In the case of ${}^{17}\mathrm{C}$, comparison is also made with the results of calculations using the transfer-to-the-continuum model. The three-dimensional momentum distributions computed within the sudden approximation model exhibit longitudinal and transverse momentum components that are strongly coupled by the reaction for $s$-wave states, while no such effect is apparent for $d$ waves. Incomplete detection of transverse momenta arising from limited experimental acceptances thus leads to a narrowing of the longitudinal distributions for nuclei with significant $s$-wave valence neutron configurations, as confirmed by the data. Asymmetries in the longitudinal momentum distributions attributed to diffractive dissociation are also explored.

Neutron-induced fission cross-section ratios ${}^{\mathrm{nat}}\mathrm{Pb}∕{}^{209}\mathrm{Bi},{}^{208}\mathrm{Pb}∕{}^{209}\mathrm{Bi},{}^{197}\mathrm{Au}∕{}^{209}\mathrm{Bi},{}^{\mathrm{nat}}\mathrm{W}∕{}^{209}\mathrm{Bi},{}^{181}\mathrm{Ta}∕{}^{209}\mathrm{Bi}$, and ${}^{209}\mathrm{Bi}∕{}^{238}\mathrm{U}$ have been measured in the 30–180 MeV energy range using the neutron beam facility at The Svedberg Laboratory in Uppsala. The ${}^7\mathrm{Li}(p,n)$ reaction was employed as a neutron source. The fission fragments were detected by thin-film breakdown counters. Cross sections at specific energies were determined using unfolding techniques with respect to the excitation function and the neutron spectra, the latter obtained from recent measurements and an evaluation. The absolute fission cross sections were obtained using the standard ${}^{238}\mathrm{U}(n,f)$ cross section. The ${}^{\mathrm{nat}}\mathrm{W}(n,f)$ and ${}^{181}\mathrm{Ta}(n,f)$ cross sections have been measured for the first time. The results for ${}^{209}\mathrm{Bi}(n,f),{}^{\mathrm{nat}}\mathrm{Pb}(n,f),{}^{208}\mathrm{Pb}(n,f)$, and ${}^{197}\mathrm{Au}(n,f)$ cross sections have been compared with available literature data. A universal easy-to-use parametrization has been suggested for all measured cross sections. The common features of subactinide neutron-induced fission cross sections are found to be similar to those of the proton-induced fission data.

A direct derivation of the operator structure for two spin-$\frac{1}{2}$ particles is presented subject to invariance under basic symmetries and Galilean frame transformation. The partial wave decomposition for coefficient functions, valid on- and off-shell, is explicitly deduced. The momentum transfer representation and angular momentum decomposition for general spin-dependent potentials are obtained.

We use the stability conditions of the Landau parameters for the symmetric nuclear matter and pure neutron matter to calculate the critical densities for the Skyrme type effective nucleon-nucleon interactions. We find that the critical density can be maximized by appropriately adjusting the values of the enhancement factor $\kappa$ associated with isovector giant dipole resonance, the quantity $L$, which is directly related to the slope of the symmetry energy, and the Landau parameter $G_0^{\prime }$. However, restricting $\kappa ,L$, and $G_0^{\prime }$ to vary within acceptable limits reduces the maximum value for the critical density ${\tilde{\rho }}_{\mathit{cr}}$ by $\sim 25\%$. We also show that among the various quantities characterizing the symmetric nuclear matter, ${\tilde{\rho }}_{\mathit{cr}}$ depends strongly on the isoscalar effective mass $m*∕m$ and surface energy coefficient $E_s$. For realistic values of $m*∕m$ and $E_s$, we get ${\tilde{\rho }}_{\mathit{cr}}=2{\rho }_0$ to $3{\rho }_0$ $({\rho }_0=0.16{\mathrm{fm}}^{-3})$.

The influence of exact angular-momentum projection and configuration mixing on properties of a heavy, well-deformed nucleus is discussed for the example of ${}^{240}\mathrm{Pu}$. Starting from a self-consistent model using Skyrme interactions, we analyze the resulting modifications of the deformation energy, the fission barrier height, the excitation energy of the superdeformed minimum associated with the fission isomer, the structure of the lowest rotational bands with normal deformation and superdeformation, and the corresponding quadrupole moments and transition moments. We present results obtained with the Skyrme interactions SLy4 and SLy6, which have slightly different surface tensions.

Full coupled channels calculations were performed for the ${}^{16}\mathrm{O}(d,n){}^{17}\mathrm{F}$ and ${}^{16}\mathrm{O}(d,p){}^{17}\mathrm{O}$ transfer reactions at several deuteron incident energies from $E_{\mathit{lab}}=2.29\mathrm{MeV}$ up to $3.27\mathrm{MeV}$. A strong polarization effect between the entrance channel and the transfer channels ${}^{16}\mathrm{O}(d,n){}^{17}\mathrm{F}(1∕2^{+},0.495)$ and ${}^{16}\mathrm{O}(d,p){}^{17}\mathrm{O}(1∕2^{+},0.87)$ was observed. This polarization effect had to be taken into account in order to obtain realistic spectroscopic factors from these reactions.

In this report we examine two topics relating to previous work. We feel that there are points to be made which we have not made before. A common thread in the two problems is that they both involve the isospin variable in an important way.

The consequences for compact star properties of including the $\delta$ mesons in the Lagrangian density of the nonlinear Walecka model are investigated. The equations of state for neutrino free and neutrino trapped with and without the $\delta$ mesons are compared. We conclude that the sensitivity to the $\delta$ mesons depends on the hadronic contents of the star, i.e., stars with only protons and neutrons behave in a different way than stars with protons, neutrons, and hyperons. Moreover, although the properties of maximum mass stable protoneutron stars with trapped neutrinos are essentially equivalent when the $\delta$ meson is included, the neutrino content is affected by its presence.

The nonleptonic weak $\mid \Delta S\mid =1\Lambda N$ interaction, responsible for the dominant nonmesonic decay of all but the lightest hypernuclei, is studied in the framework of an effective-field theory. The long-range physics is described through tree-level exchange of the SU(3) Goldstone bosons, while the short-range potential is parametrized in terms of the lowest-order contact terms. We obtain reasonable fits to available weak hypernuclear decay rates and quote the values for the parity-violating asymmetry as predicted by the present effective-field theory.

The structure of odd-mass isotopes of $\mathrm{As}$ and $\mathrm{Ge}$ is described in the framework of the proton-neutron interacting boson-fermion model. The energy levels and the electromagnetic properties of ${}^{69,71,73}\mathrm{As}$ and ${}^{69,71,73}\mathrm{Ge}$ are calculated and compared with the experiment. The $\beta$-decay rates from the $\mathrm{As}$ isotopes to the $\mathrm{Ge}$ isotopes are calculated. The calculated decays tend to be stronger than the observed ones. This may indicate a mixture of components outside the model space in the wave functions of actual nuclei. The effect of the higher-order terms in the decay operators seems small.

The two-neutrino double-$\beta$ $\left(2\nu \beta \beta \right)$ decay represents a test case for our knowledge about the nuclear structure of the involved isobars. The decay of ${}^{48}\mathrm{Ca}$ is an especially interesting case because it holds an anomaly of a uniquely high $Q_{\beta \beta }$ value and a comparatively long half-life, which points to a peculiar nuclear structure situation. The nuclear matrix element relevant for $\beta \beta$ decay can be calculated, if the complete set of Gamow-Teller (GT) matrix elements for the two virtual transitions in the perturbative description are known. Using the high-resolution $(d,{}^2\mathrm{He})$ probe, we have measured the ${\mathrm{GT}}^{+}$ strength distribution in ${}^{48}\mathrm{Sc}$, which is the intermediate nucleus in the ${}^{48}\mathrm{Ca}\beta \beta$ decay. By combining our measured GT distribution with data from a ${}^{48}\mathrm{Ca}(p,n)$ experiment and taking into account relative phases between individual matrix elements, which can be gained from theoretical models, one can compute the double-GT matrix element and deduce the half-life of the ${}^{48}\mathrm{Ca}2\nu \beta \beta$ decay.

The properties of $1_1^{-}$ two-phonon states and the characteristics of $E1$ transition probabilities between low-lying collective states in spherical nuclei are analyzed within the $Q$-phonon approach to the description of collective states. Several relations between observables are obtained. Microscopic calculations of the $E1$ $0_1^{+}\to 1_1^{-}$ transition matrix elements are performed on the basis of the random phase approximation. A satisfactory description of the experimental data is obtained.

We propose intensity interferometry with identical lepton pairs as an efficient tool for the estimation of the source size of the expanding hot zone produced in relativistic heavy ion collisions (RHIC). This can act as a complementary method to two-photon interferometry. The correlation function of two electrons with the same helicity has been evaluated for RHIC energies. The thermal shift of the $\rho$ meson mass has negligible effects on the Hanbury Brown–Twiss radii.

The difference between the structures of jets produced in heavy-ion and hadronic collisions can best be exhibited in the correlations between particles within those jets. We study the dihadron correlations in jets in the framework of parton recombination. Two types of triggers, ${\pi }^{+}$ and proton, are considered. It is shown that the recombination of thermal and shower partons makes the most important contribution to the spectra of the associated particles at intermediate $p_T$. In $pp$ collisions the only significant contribution arises from shower-shower recombination, which is negligible in heavy-ion collisions. Moments of the associated-particle distributions are calculated to provide a simple summary of the jet structures for easy comparison with experiments.

The nuclear physics relevant to the electric dipole moment (EDM) of the deuteron is addressed. The general operator structure of the $P$- and $T$-odd nucleon-nucleon interaction is discussed and applied to the two-body contributions of the deuteron EDM, which can be calculated in terms of $P$- and $T$-odd meson-nucleon coupling constants with only small model dependence. The one-body contributions, the EDMs of the proton and the neutron, are evaluated within the same framework. Although the total theoretical uncertainties are sizable, we conclude that, compared to the neutron, the deuteron EDM is competitive in terms of sensitivity to $\mathit{CP}$ violation, and complementary with respect to the microscopic sources of $\mathit{CP}$ violation that can be probed.

The correlated two-pion exchange in the mesonic $\sigma$ channel as derived using chiral symmetry and large-$N_c$ constraints is shown to improve the description of the proton-proton $\left(pp\right)$ peripheral partial waves $(L⩾3)$ below and above the inelastic threshold. With inclusion of one-pion exchange it, furthermore, can account for the energy dependence observed for uncoupled partial waves. The coupled waves are signaling the need for an additional long-range tensor force.

Experiments can only determine a theory up to an overall scattering equivalence. The freedom to use different scattering equivalent theories is a useful tool for simplifying the structure of dynamical models of physical systems. This paper illustrates how scattering equivalences can be used to simplify current operators in relativistic constituent quark models.

A nonperturbative renormalization scheme for nucleon-nucleon interaction based on boundary conditions at short distances is presented and applied to the one pion exchange potential. It is free of off-shell ambiguities and ultraviolet divergences, provides finite results at any step of the calculation, and allows us to remove the short distance cutoff in a suitable way. Low energy constants and their nonperturbative evolution can be directly obtained from experimental threshold parameters in a completely unique and model independent way when the long range explicit pion effects are eliminated. This allows us to compute scattering phase shifts which are, by construction, consistent with the effective range expansion to a given order in the center of mass (c.m.) momentum $p$. In the singlet ${}^{1}S_0$ and triplet ${}^{3}S_1\text{−}{}^{3}D_1$ channels ultraviolet fixed points and limit cycles are obtained, respectively, for the threshold parameters. Data are described satisfactorily up to c.m. momenta of about $p\sim m_{\pi }$.

We investigate parity-violating observables in the $np$ system, including the longitudinal asymmetry and neutron-spin rotation in $\vec{n}p$ elastic scattering, the photon asymmetry in $\vec{n}p$ radiative capture, and the asymmetries in deuteron photodisintegration $d(\vec{\gamma },n)p$ in the threshold region and electrodisintegration $d(\vec{e},e^{\prime })np$ in quasielastic kinematics. To have an estimate of the model dependence for the various predictions, a number of different, latest-generation strong-interaction potentials—Argonne $v_{18}$, Bonn 2000, and Nijmegen I—are used in combination with a weak-interaction potential consisting of $\pi$-, $\rho$-, and $\omega$-meson exchanges—the Desplanques-Donoghue-Holstein (DDH) model. The complete bound and scattering problems in the presence of parity-conserving, including electromagnetic, and parity-violating potentials are solved in both configuration and momentum space. The issue of electromagnetic current conservation is examined carefully. We find large cancellations between the asymmetries induced by the parity-violating interactions and those arising from the associated pion-exchange currents. In the $\vec{n}p$ capture, the model dependence is nevertheless quite small, because of constraints arising through the Siegert evaluation of the relevant $E_1$ matrix elements. In quasielastic electron scattering these processes are found to be insignificant compared to the asymmetry produced by $\gamma \text{−}Z$ interference on individual nucleons. These two experiments, then, provide clean probes of different aspects of weak-interaction physics associated with parity violation in the $np$ system. Finally, we find that the neutron-spin rotation in $\vec{n}p$ elastic scattering and asymmetry in deuteron disintegration by circularly polarized photons exhibit significant sensitivity both to the values used for the weak vector-meson couplings in the DDH model and to the input strong-interaction potential adopted in the calculation. This reinforces the conclusion that these short-ranged meson couplings are not in themselves physical observables; rather, the parity-violating mixings are the physically relevant parameters.