Table of contents

The authors construct an empirical weak parity-non-conserving potential from the presently available experimental data on parity mixtures on nuclei. A feature of this potential, which provides a reasonable fit to the data, is the strongly enhanced Delta T=2 component. This is demanded by the observed circular polarization of the photon emitted in n+p to d+ gamma , and independently by the observed parity mixtures in heavy nuclei. The Delta T=1 potential is also enhanced, suggesting the presence of neutral currents.

It is demonstrated that for nonlocal potentials the quadrupole moment of the deuteron is not determined by the parameters which describe the scattering in the ³S₁-³D₁ state.

The charge dependence of the effective nucleon-nucleon interaction in asymmetric nuclear matter is investigated within the framework of the lowest-order Brueckner theory. The reaction matrix is calculated self-consistently from the Reid soft-core potential at the normal nuclear density. Even at alpha =(N-Z)/A=0.4 the charge dependence is found to be very weak.

The authors re-examine the problem of determining short-range correlations by sum rules for cross sections at constant momentum transfer. Using the model-independent analysis technique, they find that knowledge of the summed cross sections for momentum transfers 3 fm^-1 to 4.5 fm^-1 is crucial for observation of short-range repulsion. Unfortunately, meson production will obscure the interpretation of the data in just this region.

The author considers three possible models of the elastic nucleus-nucleus channel. The nuclei are described by their undisturbed densities (first model) or by their undisturbed wavefunctions (second model). The third model uses the adiabatic description. The result of an alpha-decay calculation uniquely qualifies the second model as the best one. This conclusion is valid for energies of relative motion which are a few MeV per nucleon or higher when the nuclei are in contact. The physics of alpha decay is also discussed in connection with these models.

Shell-model calculations have been performed for positive parity levels in ²⁵Mg with the fitted interaction of Preedom and Wildenthal (see Phys. Rev. C, vol.6, p.1633 of 1972). All possible sd-shell configurations are included. Calculated electromagnetic decay properties and level energies are compared with recent data for levels up to about 6 MeV. The agreement achieved is in general good.

Elastic proton-deuteron scattering at energies near threshold is studied using a method which allows the effective, energy-dependent proton-deuteron potential to be given in closed form if the nuclear part of the two-nucleon potential is assumed to be separable. Using the standard Yamaguchi form for the separable term, the various contributions to the effective p-d potential at sub-break-up energies are discussed, the point-charge Coulomb term is isolated and shorter-ranged corrections are developed to lowest order in the small parameter e²m^1/2/h(cross)( mod E_d mod )^1/2 approximately=0.15, where mod E_d mod is the deuteron binding energy. An analytic evaluation is given of the difference between the n-d and p-d scattering lengths in the spin-quartet channel. The result (a_pd-a_nd)_s=3/2 approximately=4.3 fm is in fair agreement with the experimental value of about 5.7 fm.

The ³⁴S( alpha ,p gamma )³⁷Cl reaction has been used to study levels in ³⁷Cl between 4 and 9 MeV in excitation. A decay scheme was determined for 21 levels by detecting proton-gamma ray coincidences, the majority of these levels being previously unreported. Angular distribution measurements were possible for ten of these levels. The Doppler-shift attenuation method was used to measure mean lifetimes as follows: 4461 keV, 60+or-45 fs; 4921 keV, 80+or-45 fs; 5379 keV, 150+or-55 fs; 6050 keV, >2 ps; 6197 keV, 320+or-80 fs; 7020 keV, >2 ps. Combining the measured mixing ratios, mean lifetimes and the results of previous work leads to the following spin and parity restrictions: 4270 keV, ³/₂⁺; 4461 keV, ⁹/₂; 5379 keV, (⁵/₂^-,⁹/₂).

Levels in ⁴¹Ca and ⁴¹K were populated using the reactions ³⁸Ar( alpha ,n)⁴¹Ca and ³⁸Ar( alpha ,p)⁴¹K. Solid ³⁸Ar targets were produced using a ⁴He refrigerator system at a mean temperature of 14K. Gamma-gamma coincidence data were collected at E_alpha =10.50, 11.50 and 15.00 MeV to study principal decay modes. In ⁴¹Ca new gamma decays from levels at 3975 and 4519 keV were found. Mean lifetimes were measured using the Doppler-shift attenuation method at several beam energies. Data were obtained for 36 levels in ⁴¹Ca and 21 levels in ⁴¹K.

The gamma rays emitted in the decay of 5.3 min ¹⁰⁶In and 6.3 min ^106mIn have been studied in singles and coincidence with Ge(Li) detectors. Decay schemes for ¹⁰⁶In and ^106mIn based on the results of these measurements are proposed. The results restrict the spins of ¹⁰⁶In and ^106mIn to the values of 3 and 3, 4 or 5 respectively with spin 5 favoured in the latter case. This is discussed in terms of j-j coupling and present knowledge of the spins of odd-odd nuclei in this region. The level scheme of ¹⁰⁶Cd is discussed.

The laser fusion computer code MEDUSA has been used to study the burn of compressed and heated DT pellets and the results have been compared with predictions obtained by the Los Alamos and KMS Fusion Inc. groups. For this study it was necessary to incorporate within MEDUSA the additional effects of heating by thermonuclear neutrons and of alpha particle transport.