Recent calculations of charge symmetry violation (CSV) in the valence quark distributions of the nucleon have revealed that the dominant symmetry breaking contribution comes from the mass associated with the spectator quark system. Assuming that the change in the spectator mass can be treated perturbatively, we derive a model-independent expression for the shift in the parton distributions of the nucleon. This result is used to derive a relation between the charge- and flavor-asymmetric contributions to the valence quark distributions in the proton, and to calculate the CSV contribution to the nucleon sea. The CSV contribution to the Gottfried sum rule is also estimated, and found to be small.

Parity nonconservation (PNC) was studied for 24 p-wave neutron resonances in ${}^{238}\mathrm{U}$ from 10 to 300 eV by measuring the helicity dependence of the total neutron cross section with an improved experimental apparatus. Six resonances show statistically significant (greater than $2.9\sigma )$ parity violation. An analysis treating the PNC matrix elements as random variables yields a root-mean-square PNC matrix element ${M=0.67\mathrm{}}_{-0.16}^{+0.24\mathrm{}}$ meV. The corresponding weak spreading width ${\Gamma }_w{=(1.35\mathrm{}}_{-0.64}^{+0.97\mathrm{}})\times {10}^{-7}$ eV.

Parity nonconservation (PNC) was measured for 24 $p$-wave resonances from 8 to 300 eV in ${}^{232}\mathrm{Th}$ by measuring the helicity dependence of the total neutron cross section for epithermal neutrons with an improved experimental system. Ten resonances show statistically significant parity violation. For these ten resonances the analyzing powers are all positive, thus confirming the previously observed sign correlation. The data are fit to the sum of two terms, a constant asymmetry and a fluctuating asymmetry. With this ansatz the root-mean-square PNC matrix element $M=1.12\mathrm{}$ meV, which corresponds to a weak spreading width ${\Gamma }_w=4.7\mathrm{}\times {10}^{-7}$ eV. For the neighboring nuclide ${}^{238}\mathrm{U}$ there is no constant offset, suggesting that the sign correlation is specific to ${}^{232}\mathrm{Th}$.

Quasiparticle-random-phase-approximation (QRPA) calculations of double $\beta$ decays have not been able to reproduce data in the $A=100\mathrm{}$ system. We propose the $A=116\mathrm{}$ system—because of its smaller deformation—as a simpler system to test QRPA calculations. We present results of two experiments we performed, which determine the electron-capture-decay branch of ${}^{116}\mathrm{In}$ to be $(2.27\mathrm{}\pm 0.63)\times {10}^{-2}\%$, from which we deduce $\log {ft=4.39\mathrm{}}_{-0.15}^{+0.10\mathrm{}}$. We present QRPA calculations and compare their predictions to experimental data. Finally we use these calculations to predict the $2\nu$ double-$\beta$-decay rate of ${}^{116}\mathrm{Cd}$ to the ground and excited states of ${}^{116}\mathrm{Sn}$.

The inner crust of a neutron star is a superfluid and inhomogeneous system, consisting of a lattice of nuclei immersed in a sea of neutrons. We perform a quantum calculation of the associated pairing gap and compare it to the results one obtains in the local density approximation (LDA). It is found that the LDA overestimates the spatial dependence of the gap, and leads to a specific heat of the system which is too large at low temperatures, as compared with the quantal result. This is caused by the neglect of proximity effects and the delocalized character of the single-particle wave functions close to the Fermi energy. It is possible to introduce an alternative, simple semiclassical approximation of the pairing gap which leads to a specific heat that is in good agreement with the quantum calculation.

The cross section for the proton weak capture reaction ${}^1\mathrm{H}{(p,e}^{+}{\nu }_e{)}^2\mathrm{H}$ is calculated with wave functions obtained from a number of modern, realistic high-precision interactions. To minimize the uncertainty in the axial two-body current operator, its matrix element has been adjusted to reproduce the measured Gamow-Teller matrix element of tritium $\beta$ decay in model calculations using trinucleon wave functions from these interactions. A thorough analysis of the ambiguities that this procedure introduces in evaluating the two-body current contribution to the $\mathrm{pp}$ capture is given. Its inherent model dependence is in fact found to be very weak. The overlap integral ${\Lambda }^2\mathrm{}(E=0\mathrm{})\mathrm{}$ for the $\mathrm{pp}$ capture is predicted to be in the range 7.05–7.06, including the axial two-body current contribution, for all interactions considered.

The sensitivity of the Sudbury Neutrino Observatory (SNO) to measure the shape of the recoil electron spectrum in the charged-current reaction of ${}^8\mathrm{B}$ solar neutrinos interacting with deuterium can be improved if the results of a ${}^8\mathrm{Li}$ beta-decay calibration experiment are included in the test. We calculate an improvement in sensitivity, under certain idealistic assumptions, of about a factor of 2, sufficient to resolve different neutrino-oscillation solutions to the solar-neutrino problem. We further examine the role of recoil and radiative corrections on both the ${}^8\mathrm{B}$ neutrino spectrum and the ${}^8\mathrm{Li}$ electron spectrum and conclude that the influence of these effects on the ratio of the two spectra as measured by the SNO is very small.

The radiative corrections for neutrino-deuterium scattering are computed for the charged-current (CC) reaction, ${\nu }_e+\overrightarrow{d}{p+p+e}^{-},$ and for the neutral-current (NC) reaction, ${\nu }_x+\overrightarrow{d}p+n+{\nu }_x.$ Nonrelativistic kinematics are used for the hadrons, which considerably simplifies the calculations. The impact radiative corrections have on the observables to be detected in the Sudbury Neutrino Observatory (SNO) are discussed and for most observables is found to be negligible. Only in the case where the internal bremsstrahlung photons emitted in the reaction ${\nu }_e+\overrightarrow{d}{p+p+e}^{-}+\gamma$ are detected, is the expectation for the ratio of the number of CC to the number of NC events seen in SNO shifted by about one standard deviation.

We study the influence of a possible H dibaryon condensate on the equation of state and the overall properties of neutron stars whose population otherwise contains nucleons and hyperons. In particular, we are interested in the question of whether neutron stars and their masses can be used to say anything about the existence and properties of the H dibaryon. We find that the equation of state is softened by the appearance of a dibaryon condensate and can result in a mass plateau for neutron stars. If the limiting neutron star mass is about that of the Hulse-Taylor pulsar a condensate of H dibaryons of vacuum mass $\sim 2.2\mathrm{GeV}$ and a moderately attractive potential in the medium could not be ruled out. On the other hand, if the medium potential were even moderately repulsive, the H would not likely exist in neutron stars. If neutron stars of mass $\sim {1.6M}_{\odot }$ were known to exist, attractive medium effects for the H could be ruled out.

Cascade hypernuclei have been studied in the ${(K}^{-}{,K}^{+})$ reaction on a scintillating fiber target. The experimental result is compared with a theoretical calculation in order to extract information concerning the ${\Xi }^{-}$ nucleus potential.

With the use of a fragment mass analyzer, the $\alpha$ decay of ${}^{180}\mathrm{Tl}$ was identified in ${}^{92}\mathrm{Mo}$ bombardments of ${}^{90}\mathrm{Zr}.\mathrm{}$ At least three α transitions were observed but on the basis of the data obtained it was not possible to conclude if they originate from one or more levels in ${}^{180}\mathrm{Tl}.\mathrm{}$ In the same irradiations a new α group was also identified in ${}^{179}{\mathrm{Tl}}^m$ decay. Based on energy and half-life systematics, it appears that ${}^{179}{\mathrm{Tl}}^m,$ in contrast to the isomers in heavier odd-A Tl nuclei, is not the $h_{9/2}$ intruder level but rather the $h_{11/2}$ proton state.

Longitudinal polarization-transfer coefficients for the ${}^3\mathrm{H}(\overrightarrow{p},\overrightarrow{n}{)}^3\mathrm{He}$ reaction have been measured at zero degrees for proton energies of 1.3–2.8 MeV. The results show a striking resonance behavior for energies corresponding to excitation of the $0^{-}$ level in ${}^4\mathrm{He}$ at 21.0 MeV. In agreement with $R$-matrix calculations, the value approaches unity at 1.52 MeV, the peak of the resonance. Near this same energy, at 1.62 MeV, the transverse polarization-transfer coefficient was measured to be consistent with zero.

The lifetime of the 773 keV $\pi g_{9/2}$ isomer in ${}^{79}\mathrm{As}$ has been measured to be $T_{1/2}=0.87\mathrm{}\left(6\right)\mathrm{}\hspace{0.5em}\mu \mathrm{s}$ by taking coincidences between $\gamma$ rays and projectilelike fragments produced in deep-inelastic collisions of ${}^{198}\mathrm{Pt}{+}^{76}\mathrm{Ge}$ (635 MeV). The ${B(M2,9/2\mathrm{}}^{+}\to {5/2}^{-})$ value for the 542 keV transition in ${}^{79}\mathrm{As}$ is found to be 0.042(3) Weisskopf units (W.u.). An identification method of nuclei produced in deep-inelastic collisions is also described.

High-spin states of ${}^{153}\mathrm{Tb}$ were populated via the reaction ${}^{139}{\mathrm{L}\mathrm{a}(}^{18}\mathrm{O},4n)$ at a beam energy of 100 MeV. Previously known bands have been extended beyond the region of the first $i_{13/2}$ neutron alignment and two new structures have been identified. The rotational alignment behavior of the $\pi h_{11/2}$ and new bands are discussed. Quasiparticle assignments are suggested for the latter. $B\left(M1\mathrm{}\right)/B\left(E2\mathrm{}\right)\mathrm{}$ ratios were extracted and compared to theoretical calculations.

The polarization transfer coefficient $K_y^{y^{\prime }}$ has been measured for neutron-proton scattering at $E_n=15.8\mathrm{}\mathrm{MeV}$ and ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=132.4\mathrm{}°.$ Using a quasimonoenergetic polarized neutron beam produced via the ${}^2\mathrm{H}{\mathrm{}(d,n)\mathrm{}}^3\mathrm{He}$ reaction, and a liquid-helium proton polarimeter, a value of $K_y^{y^{\prime }}=0.160\mathrm{}\pm 0.020$ has been obtained which is appreciably smaller than the predictions of all realistic, meson-based $N-N$ potentials but agrees well with the result of an earlier measurement at 17.4 MeV.

Two new neutron-rich rare-earth isotopes ${}^{161}\mathrm{Sm}$ and ${}^{165}\mathrm{Gd}$ produced in the proton-induced fission of ${}^{238}\mathrm{U}$ were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives were determined to be 4.8±0.8 s for ${}^{161}\mathrm{Sm}$ and 10.3±1.6 s for ${}^{165}\mathrm{Gd}.$ The assignment of these isotopes was based upon the observation of Eu and Tb K x rays in the $\beta$-gated x/$\gamma$-ray spectra measured for the separated mass fraction 177 and 181 as monoxide ions ${}^{161}{\mathrm{Sm}}^{16}{\mathrm{O}}^{+}$ and ${}^{165}{\mathrm{Gd}}^{16}{\mathrm{O}}^{+},$ respectively.

The processes involving $K^{-}p,KN,\Sigma \pi ,\Lambda \pi ,\Sigma \eta ,\Lambda \eta$ coupled channels are studied in the nonperturbative chiral approach. An effective potential is constructed using a chiral meson-baryon Lagrangian at lowest order. This potential is iterated to all orders with the Lippmann-Schwinger equation. A reasonable fit of the experimental data is obtained. It is pointed out, however, that due to a strong sensitivity of the results to the value of the cutoff, such an approach should be viewed as a rather phenomenological way to fit the experimental data since there is no small expansion parameter allowing for truncation of the chiral expansion of the effective potential at some given order. A possible way to construct the consistent chiral expansion is briefly discussed.

We investigate the Coulomb dissociation of two-neutron halo nuclei, assuming that the excitation of the projectile is to states in the continuum with low energy. The method presented retains all finite-range effects associated with the interactions between the breakup fragments and can use realistic three-body wave functions for the two-neutron halo nuclei. The method is applied to ${}^6\mathrm{He}$, at incident energies below 100 MeV/nucleon, and calculations are compared with available data for the $\alpha$-particle energy spectrum following the breakup of ${}^6\mathrm{He}$ on a heavy target.

The necessary condition is found that the coherent state assumed in the mean-field approximation is reliable for describing the charged boson condensation. The relevance to the kaon condensation in nuclear matter is also discussed.

We study the effects of the Coulomb interaction on the growth of unstable modes in asymmetric nuclear matter. In order to compare with previous calculations we use a semiclassical approach based on the linearized Vlasov equation. Moreover, a quantum calculation is performed within the random phase approximation. The Coulomb effects are a slowing down of the growth and the occurrence of a minimal wave vector for the onset of the instabilities. The quantum corrections cause a further decrease of the growth rates.